Ionic Phenomena: A Study - Sofad

Ionic Phenomena: A Studyof an Environmental ProblemPSC-4012-2Learning Guide

IONIC PHENOMENA: A STUDY

OF AN ENVIRONMENTAL PROBLEM

PSC-4012-2

LEARNING GUIDE

Ionic Phenomena: A Study of an Environmental Problem is part of a set of threecourses that make up the Secondary IV Physical Science program. The othertwo courses are:

PSC-4010-2 Nuclear Technology: A Matter of Energy

PSC-4011-2 Electricity: What's the Connection?

IONIC PHENOMENA: A STUDYOF AN ENVIRONMENTAL PROBLEM

Author: Danielle Ouellet

Updated Version: Ronald MongeauCéline Tremblay

Program Coordinators at the DFGA: Serge LeloupPierrette Marcotte

Production Coordinator at SOFAD: Jean-Simon Labrecque

Production Coordinator (1st edition): Mireille Moisan

Production Coordinator at the DFGA: Pauline Pelletier

Content Revisor: Céline Tremblay (French Version)John Allen (English Version)

Verification of Experiments: Annick Charlebois

Illustrations: Jean-Philippe Morin

Graphics: Science-Impact

Layout: Sylvain Nadeau

Translation and Linguistic Revision: Direction de la production en langue anglaiseServices à la communauté anglophoneMinistère de l'Éducation

First edition: September 1998 The preliminary version of this guide was produced by the Direction de la formationgénérale des adultes (DFGA). After this course was field-tested, the guide was updatedby SOFAD.

February 2009

We would like to thank the following people, who contributed to the preliminary version of thisdocument:

André Dumas Commission scolaire catholique de Sherbrooke

Janine Gomel Direction du développement de la formation à distance

Serge Marcil Commission des écoles catholiques de Montréal

Almas Simard Commission scolaire de Chicoutimi

Céline Tremblay Consultant, FormaScience

We would also like to thank the following teachers, who helped field-test the preliminaryversion of this document:

Suzy Asselin Commission scolaire catholique de Sherbrooke

Lyne Desranleau Commission scolaire Saint-Jean-sur-Richelieu

Danielle Houde Commission scolaire de Chicoutimi

Ronald Mongeau Commission scolaire du Sault-Saint-Louis

© Société de formation à distance des commissions scolaires du Québec

All rights for translation and adaptation, in whole or in part, reserved for all countries. Anyreproduction by mechanical or electronic means, including microreproduction, is forbiddenwithout the written permission of a duly authorized representative of the Société de formationà distance des commissions scolaires du Québec.

Legal Deposit–1998Bibliothèque et Archives nationales du QuébecBibliothèque et Archives CanadaISBN 978-2-89493-126-4

0.5TABLE OF CONTENTS© SOFAD

TABLE OF CONTENTS

GENERAL INTRODUCTION

Overview

The Physical Science Program ............................................................... 0.13

Ionic Phenomena: A Study of an Environmental Problem ................... 0.13

Objectives ................................................................................................. 0.14

How to Use This Learning Guide .................................................................... 0.21

Information for Distance Education Students ............................................... 0.23

Work Pace ................................................................................................ 0.23

Materials .................................................................................................. 0.23

Learning Activities ................................................................................... 0.24

Experiments ............................................................................................. 0.24

Exercises .................................................................................................. 0.25

Self-Evaluation Test ................................................................................ 0.25

Your Tutor ............................................................................................... 0.25

Homework Assignments ......................................................................... 0.26

Certification ............................................................................................. 0.26

Useful Information .................................................................................. 0.27

Mathematical Prerequisites ............................................................................. 0.28

How to Round Off a Number ................................................................. 0.28

The Metric System................................................................................... 0.29

An Important Property of Proportions ................................................... 0.30

Formulas .................................................................................................. 0.31

Scientific Notation .................................................................................. 0.32

Ionic Phenomena: A Study of an Environmental Problem .............................. 0.33

LEARNING ACTIVITIES

Chapter 1: Poison from the Sky

Problems Related to the Use of Chemicals ..................................................... 1.6

Water Pollution Problems ....................................................................... 1.7

A Country Built on Water Resources ............................................. 1.7

Atmospheric Pollution Problems............................................................ 1.11

The Ozone Layer ............................................................................. 1.11

The Greenhouse Effect ................................................................... 1.13

Acid Rain ......................................................................................... 1.14

Case Study ........................................................................................................ 1.16

Case-Study Outline .................................................................................. 1.18

Defining the Problem...................................................................... 1.19

Determining the Consequences ..................................................... 1.19

Analyzing the Solutions .................................................................. 1.19

0.6 © SOFADIONIC PHENOMENA: A STUDY OF AN ENVIRONMENTAL PROBLEM

Case Study: Acid Rain ...................................................................................... 1.20

How to Recognize Acids ......................................................................... 1.20

Experiment 1.1 One method of recognizing

acidic substances ............................................................................ 1.21

Acid Rain: How Long Have We Been Talking about It? ....................... 1.23

Acid Rain around the World ................................................................... 1.24

During Prehistory ........................................................................... 1.24

In Greece ......................................................................................... 1.25

In the Czech Republic .................................................................... 1.26

In South Africa ................................................................................ 1.27

In Canada ........................................................................................ 1.27

Acid Precipitation: What is the Situation in Québec? ........................... 1.29

Is It Possible to Reduce Acid Precipitation? .......................................... 1.29

Understanding the Nature of Acid Precipitation ................................... 1.29

Key Words in this Chapter ................................................................................ 1.31

Summary ........................................................................................................... 1.31

Review Exercises ............................................................................................... 1.32

Chapter 2: The Secrets of Matter

The Atomic Model .............................................................................................. 2.3

What Is a Model? .................................................................................... 2.3

The Simplified Atomic Model .............................................................. 2.4

Energy Levels .................................................................................... 2.7

Simplified Notation .......................................................................... 2.8

The Classification of Elements ........................................................................ 2.10

Nomenclature and Symbols .................................................................... 2.10

Elements Follow an Order ...................................................................... 2.13

The Modern Periodic Table ............................................................ 2.15

Practical Notation ........................................................................... 2.18

Discovering the Logical Relationships .......................................... 2.21

Metals, Nonmetals, and Metalloids ............................................... 2.26

The Main Chemical Families ......................................................... 2.27

Key Words in this Chapter ............................................................................... 2.33

Summary ......................................................................................................... 2.33

Review Exercises .............................................................................................. 2.36

Appendix: List of Elements .............................................................................. 2.40


Chapter 3: Matter in Action

The Transformation of Matter .......................................................................... 3.3

The Origin of Chemistry .................................................................................... 3.5

Bonds Between Atoms ....................................................................................... 3.6

How and Why? .......................................................................................... 3.9

Ionization ................................................................................................. 3.12

The Lewis Diagram .......................................................................................... 3.19

Neutral Atoms .......................................................................................... 3.20

Ions ........................................................................................................... 3.21

How Molecules Are Formed ................................................................... 3.23

Chemical Bonds ............................................................................................... 3.26

Ionic Bonds .............................................................................................. 3.27

Molecular Formulas ................................................................................ 3.31

Covalent Bonds ........................................................................................ 3.34

Electronegativity .............................................................................................. 3.41

Difference in Electronegativity..................................................................3.44

Key Words in this Chapter...................................................................................3.47

Summary ............................................................................................................3.47

Review Exercises .................................................................................................3.49

Chapter 4: Naming and Classifying Compounds

New Nomenclature ............................................................................................ 4.4

Binary Compounds.................................................................................... 4.5

Binary Molecular Compounds—Two Nonmetals .................................... 4.5

Binary Ionic Compounds—Metal and Nonmetal .................................... 4.7

Traditional Nomenclature and Complex Ionic Compounds ......................... 4.12

Acids, Bases, and Salts ..................................................................................... 4.18

A Little Bit of History .............................................................................. 4.21

First Theory ..................................................................................... 4.23

Second Theory ................................................................................ 4.24

Third Theory ................................................................................... 4.25

Dissolution ............................................................................................... 4.26

Experiment 4.1 Similar or different properties? .......................... 4.26

Ionic and Molecular Dissolution.................................................... 4.29

Dissociation Equations ................................................................... 4.32

Electrolytes and Non-Electrolytes ................................................. 4.32

A few Uses of Acids, Bases, and Salts ..................................................... 4.39


Summary ........................................................................................................... 4.40


0.8 © SOFADIONIC PHENOMENA: A STUDY OF AN ENVIRONMENTAL PROBLEM

Chapter 5: A Matter of Concentration

Compounds, Pure Substances, Mixtures ........................................................ 5.3

Concentration ................................................................................................... 5.10

Concentration in Grams per Litre .......................................................... 5.10

The Mole .................................................................................................. 5.15

Molar Concentration, or Molarity .......................................................... 5.25

Dilution .................................................................................................... 5.30

pH: a Measurement of Acidity ......................................................................... 5.36

Acid-Base Indicators ............................................................................... 5.43

Experiment 5.1 Using acid-base indicators .................................. 5.44


Summary ........................................................................................................... 5.52


Chapter 6: Nothing Is Lost, Nothing Is Gained

A Little History .................................................................................................. 6.3

Balancing Equations ......................................................................................... 6.5

How to Balance an Equation ................................................................... 6.8

Stoichiometric Calculations ............................................................................ 6.19

Acid-Base Neutralization ................................................................................. 6.30

Experiment 6.1 What a meeting! .................................................. 6.30

Neutralization Equations ........................................................................ 6.33


Summary ........................................................................................................... 6.37


Chapter 7: Case Study: Acid Precipitation

Defining the Problem ......................................................................................... 7.3

Agents Responsible for Acid Rain ............................................................ 7.5

Natural Sources ................................................................................ 7.6

Industrial Sources ............................................................................. 7.7

Scientific Aspects ..................................................................................... 7.10

Chemical Reactions ........................................................................ 7.10

The Water Cycle .............................................................................. 7.15

Transboundary Pollution ............................................................... 7.16

Determining the Consequences ....................................................................... 7.20

Environmental Consequences ................................................................ 7.21

Effects on Terrestrial Ecosystems ................................................. 7.21

Effects on Aquatic Ecosystems ...................................................... 7.22

Social Consequences ............................................................................... 7.24

Effects on Humans ......................................................................... 7.24


Economic Consequences ........................................................................ 7.26

Political Consequences ............................................................................ 7.26

Analyzing the Solutions ................................................................................... 7.29

Inventory of Possible Solutions .............................................................. 7.30

Scientific and Technical Solutions ................................................ 7.30

Political Solutions ........................................................................... 7.35

The Feasibility and Limitations of the Proposed Solutions .................. 7.39

Personal Solutions .......................................................................... 7.41

Some Practical Advice from the Québec Government ................. 7.42


Summary ...................................................................................................... 7.45


Appendix 1: The Effects of Acid Rain ............................................................... 7.55

Appendix 2: Socioeconomic Consequences of Acidification ............................ 7.58

Appendix 3: Case Study: Acid Rain .................................................................. 7.60

Appendix 4: Possible Solutions ......................................................................... 7.65

Appendix 5: Chronology of the Main Stages in Canada-U.S.

Negotiations on Acid Rain ............................................................ 7.67

Appendix 6: Resolving the Acidification Issue.................................................. 7.69

Appendix 7: Prospectus ..................................................................................... 7.71

Appendix 8: The Perfect Lawn Syndrome ......................................................... 7.72

CONCLUSIONSummary ...........................................................................................................C.3

Self-Evaluation Test ..........................................................................................C.5

Answer Key to the Self-Evaluation Test ......................................................... C.19

Answer Key to Chapter Exercises

Poison from the Sky ......................................................................................... C.29

The Secrets of Matter ....................................................................................... C.33

Matter in Action ............................................................................................... C.40

Naming and Classifying Compounds .............................................................. C.51

A Matter of Concentration ............................................................................... C.58

Nothing Is Lost, Nothing Is Gained ................................................................ C.75

Case Study: Acid Rain ...................................................................................... C.83

Bibliography ..................................................................................................... C.93

Glossary ............................................................................................................ C.95

GENERAL INTRODUCTION

GENERAL INTRODUCTION 0.13© SOFAD

OVERVIEW

The Physical Science Program

Welcome to the module entitled Ionic Phenomena: A Study of anEnvironmental Problem, which is part of the Secondary IV PhysicalScience program. This program includes two additionnal modules: NuclearTechnology: A Matter of Energy, and Electricity: What's the Connection?

This science program was designed to help you learn the fundamentalsof physics and chemistry. This basic knowledge will give you a betterunderstanding of the social and technological realities of modern society,thereby helping you become an informed citizen. This program will alsoallow you to develop an interest in science and research and prepare youfor optional Secondary V programs.

Ionic Phenomena: A Study of an Environmental Problem

Ionic Phenomena: A Study of an Environmental Problem is a learningguide designed to meet all the requirements of a Secondary IV course. Itsidentification number is PSC-4012-2. If you meet all the certificationrequirements described in the section entitled "Information for DistanceEducation Students," you will earn two credits for this course.

This module covers the main chemistry concepts and phenomenathat are essential to an understanding of the problems related to theuse of certain chemical products. It presents the different steps in acase study of the acid precipitation problem. The different causes ofacid precipitation are discussed, as well as the phases in its formation.In terms of society at large, the main development factors that havecontributed to the gradual acidification of our watercourses are exam-ined. Lastly, students are encouraged to develop their ability to makevalue judgments regarding the choices that must be made to try to solvea problem that can no longer be ignored.

0.14 IONIC PHENOMENA: A STUDY OF AN ENVIRONMENTAL PROBLEM © SOFAD

Objectives

Chapter 1: Poison from the Sky

Chapter 2: The Secrets of Matter

Terminal Objectives Intermediate Objectives

Describe the current simplified atomicmodel.

Using the electron configuration of atleast two elements, explain the relation-ship between the number of electronsin the outermost energy level and theelement's group number, and also therelationship between the number ofenergy levels and the element's periodnumber.

Describe the metals, the nonmetals andthe elements of the following chemicalfamilies: the alkali metals, alkaline earthmetals, halogens and noble gases.

Define a scientific model.

Give the characteristics of the cur-rent simplified atomic model.

Draw a diagram of the atoms of thetwenty lightest elements.

Define the expression "chemical fam-ily" or "group" as it pertains to the peri-odic table.

Define the term "period" as it pertains tothe periodic table.

Give the electron configuration of thefirst twenty elements in the periodictable, using shorthand notation.

State the relationship between the groupnumber and the number of electrons inthe outermost energy level.

State the relationship between the pe-riod number and the number of energylevels.

Indicate where the following elementsare located in the periodic table: hydro-gen, the metals, the nonmetals and thechemical families (alkali metals, alka-line earth metals, halogens and noblegases).

Indicate the properties and uses of themetals and nonmetals.

Indicate the properties and uses of thealkali metals, alkaline earth metals,halogens and noble gases.

Distinguish between hydrogen and thealkali metals.


Chapter 3: Matter in Action


Using the octet rule, explain the type ofchemical bond between two particularelements.

Distinguish between neutral atoms, ionsand isotopes as regards the number ofprotons, neutrons and electrons theyhave.

Explain the formation of binary com-pounds, using a Lewis diagram and,if appropriate, structural formula rep-resentation.

Indicate the characteristics of theelectron configuration of the noblegases (helium, neon and argon).

State the octet rule.

Determine the ionization levels of thefirst twenty elements in the periodictable.

Distinguish between ionic bonds,polar covalent bonds and non-polarcovalent bonds.

Define the term "electronegativity."

Indicate the electronegativity associ-ated with ionic, polar covalent andnon-polar covalent bonds.

Using the electronegativity table,determine the type of bond (ionic,polar covalent or non-polar covalent)between two given elements.

Determine the number of protons,neutrons and electrons of an elementwhose atomic number and atomicmass are known.

Determine the charge of an ion whoseatomic number or chemical family isknown.

Compare the electron configurationof an ion with that of the correspond-ing neutral atom.

Describe the isotopes of a givenelement.

Distinguish between atomic mass andmass number.

Identify anions and cations.

Determine the charge of each ion.

Represent the ions, using a Lewisdiagram.


Determine the molecular formula of abinary compound.

Chapter 4: Naming and Classifying Compounds


According to the new nomenclature,give the name of a binary compoundwhose chemical formula is known orthe chemical formula of a binary com-pound whose name is known.

According to the traditional nomencla-ture, give the name of a polyatomiccompound whose chemical formula isknown or the chemical formula of apolyatomic compound whose name isknown.

Represent the compound formed byionic or covalent bonds, using a Lewisdiagram.

Represent the compound formed bycovalent bonds, using structural for-mula representation.

Draw a diagram representing the chemi-cal reaction between an element fromgroup I or II and an element fromgroup VI or VII, using the current sim-plified atomic model.

Distinguish between an element and acompound.

Identify anions and cations.

Determine the charge of the anion andcation on the basis of the octet rule or thechemical family.

Determine the number of anions andcations necessary for the formation of abinary compound.

Know the principal suffixes used to des-ignate binary compounds in the newnomenclature.

Know the significance of the prefixesused to designate the number of a typeof atom.

Know the method for naming a binarycompound according to the newnomenclature.

Know how to write the formula of abinary compound according to the newnomenclature.

Know the principal suffixes used to des-ignate polyatomic compounds in the tra-ditional nomenclature.

Know the significance of the prefixesused to designate the number of a type ofatom or of polyatomic ions.


Using characteristics and equations fordissociation, explain why a substance isan acid, a base or a salt.

On the basis of experimental results,classify a substance as a non-electro-lyte, a strong electrolyte, a weak elec-trolyte, a strong acid, a weak acid, astrong base, a weak base or a salt.

In molecular terms, explain the disso-lution in an aqueous solution of thefollowing substances: non-electrolytes,strong electrolytes, weak electrolytes,strong acids, weak acids, strong bases,weak bases and salts.

Know the method for naming apolyatomic compound according tothe traditional nomenclature.

Know how to write the formula of apolyatomic compound according to thetraditional nomenclature.

Distinguish among the characteristicsof acids, bases and salts.

Describe Arrenhius' ionization theoryconcerning acids and bases.

Distinguish among equations for thedissociation of acids, bases, and salts.

By conducting an experiment,distinguish between a moleculardissolution and an ionic dissolution.

By conducting an experiment,distinguish between an electrolyteand a non-electrolyte.

By conducting an experiment,distinguish between a strong electro-lyte and a weak electrolyte.

By conducting an experiment,distinguish between a strong acidand a weak acid.

By conducting an experiment,distinguish between a strong baseand a weak base.

Distinguish between moleculardissolution and ionic dissolution.

Distinguish between electrolytes andnon-electrolytes.

Distinguish between strong electro-lytes and weak electrolytes.

Distinguish between strong acids andweak acids.

Distinguish between strong bases andweak bases.


Chapter 5: A Matter of Concentration


Classify a substance according towhether it is a mixture or a pure sub-stance and, if a mixture, whether it ishomogeneous, heterogeneous or a sus-pension and, if a pure substance,whether it is an element or a com-pound.

Compare solutions whose concentra-tions are expressed in different units.

Solve problems pertaining to dilution.

Indicate the two categories into whichmatter is classified.

Describe the three categories of mix-tures.

Indicate the two categories of pure sub-stances.

Distinguish between solvent andsolute.

Distinguish between homogeneousmixture and heterogeneous mixture.

Give the definition and the equation fora concentration.

Given a mass in kilograms, express it ingrams.

Given a volume in millilitres, express itin litres.

Solve problems about the concentra-tion of solutions expressed in terms ofmass of solute per volume of solution.

Define the term "mole."

Calculate the molar mass of a com-pound on the basis of the atomic massof its constituent elements.

Given a quantity of matter expressed ingrams, convert it into moles and viceversa.

Solve problems about the concentra-tion of solutions expressed in molesper litre.

Given a volume of solution in millilitres,express it in litres.

Define the term "dilution."

State the mathematical relationshipbetween the characteristics (volume andconcentration) of the stock solutionand those of the diluted solution.


Rank solutions whose acidity isexpressed in different units.

Determine the pH range of a solutionon the basis of data or results obtainedfrom acid-base indicators whose turn-ing points are known.

Chapter 6: Nothing Is Lost, Nothing Is Gained


Express various chemical reactions asbalanced equations.

Using stoichiometric calculations,determine the quantity of the substancesinvolved in a chemical reaction.

Using equations, explain how neutral-ization can offer a solution to an acid-base imbalance.

Define the term "pH."

Given the pH of a solution, deter-mine whether it is acidic or basic.

Give the pH of a concentration of H+

expressed in moles per litre (mol/L)and vice versa.

Define the term "turning point."

Indicate the turning point of the acid-base indicators.

By conducting an experiment, deter-mine the turning point of acid-baseindicators.

Distinguish between the reactants andthe products in a chemical reaction.

Write the equation for a chemical reac-tion on the basis of a descriptivestatement.

Balance chemical equations.

Verify the law of the conservation ofmatter on the basis of a balancedequation.

Balance the reaction equation.

Express in moles the proportions ofthe reactants and the products.

Express in grams the proportions ofthe reactants and the products.

Write the equations used for thedissociation constant of acids andbases.

Define the term "neutralization."

Write the balanced equation for theneutralization of a simple acid by asimple base.

Recognize the equations for neu-tralization.


Chapter 7: Case Study: Acid Precipitation


Describe a problem related to the use ofchemicals.

Make a complete list of the conse-quences of a problem related to the useof chemicals.

Analyze potential solutions to a prob-lem involving the use of chemicals.

Evaluate articles about problemsrelated to the use of chemicals byfocusing on the description of the prob-lem, its consequences and the proposedsolutions.

Describe the historical evolution of theproblem.

Identify the chemicals that caused theproblem.

Explain the scientific and technical fac-tors involved.

Indicate the environmental effects ofthe problem.

Indicate the social, political and eco-nomic consequences of the problem.

List the potential solutions.

Indicate the feasibility and limitationsof each of the solutions proposed.

Assess the scientific, technical, social,political and economic value of thesolutions proposed.


HOW TO USE THIS LEARNING GUIDE

This course applies the main principles of individualized learning,which encourage you to:

– take an active part in the learning process;– take responsibility for your own progress;– work at your own pace;– put your knowledge and experience to use.

As you work through this course at your own pace, you will be able toidentify your strengths and weaknesses, discover the reasons for anyproblems you may have and decide what steps you must take to resolvethese problems so you can continue to make progress.

Throughout this course, you will be able to consult your teacher if youare experiencing any difficulty. He or she will provide you with advice,encouragement, and constructive comments and feedback, adaptingthese services to meet your specific needs.

This learning guide is divided into three parts: the general introduc-tion, the learning activities and the conclusion.

Part I provides a general introduction to the course, outlining itsobjectives and providing the information you will need to get started. Italso includes a section entitled "Mathematical Prerequisites," which dealswith the different concepts you should be familiar with before beginningthis course.

Part II consists of the learning activities, which have been divided intoseven chapters. Each chapter covers a certain number of themes usingexplanations, tables, illustrations, exercises, activities, and experiments.Each chapter begins with a list of objectives and a diagram showing wherethe chapter falls within the course. It ends with a list of key words, asummary, and review exercises that will help you go over what you havelearned. Complementary reading material is found in the appendices tochapters 2 and 7.

The last chapter provides a wealth of information on social issues. Byreading the related articles found in the appendices, you will develop skillsthat will help you analyze particular situations.

This guide is organized in such a way that you must work through itchapter by chapter. The questions and exercises will help you evaluateyour knowledge as you go along.


Throughout this guide, you will encounter different symbols, picto-graphs, and typefaces, which are explained below.

Bold Words mentioned for the first time are printed in bold anddefined. In some cases, the initial definition is expanded onlater and a more formal definition is given in the glossarysection at the end of the guide. Most of these words are alsofound in the list of key words at the end of each chapter andin a special supplement where you must write your owndefinition of these terms.

A light bulb indicates additional information: this informa-tion is not part of the course as such and will not be coveredon the final examination (summative evaluation).

A hand signals an "Activity." These sections will guide youthrough exercises designed to help you master the conceptsyou have studied.

A flask signals an "Experiment." In order to help you betterunderstand different situations or account for differentphenomena, you will be asked to perform experimentseither in a laboratory or using the experiment kits providedby Formation à distance.

The conclusion, Part III, summarizes what you have learned in all thecourses in the program. It also contains a self-evaluation test to help youdetermine whether you have mastered the subject matter of this courseand are therefore ready to write the final examination. The conclusion alsoincludes an answer key for the self-evaluation test, for the exercises in eachchapter, and for the activities, experiments, and review exercises. Aglossary containing definitions of the key words and a bibliography of thematerials used to produce this learning guide completes Part III. You maywish to consult these books and publications for further information onthe topics covered in this course.

Good luck!


INFORMATION FOR DISTANCE EDUCATION STUDENTS

This guide is the main work tool for this course and has been designedto meet the specific needs of adult students taking distance educationcourses.

Distance education is a flexible system with several advantages, one ofwhich is the opportunity to work at your own pace in the comfort of yourown home. This system does, however, involve certain challenges: youhave to take responsibility for your own learning and motivate yourself towork at a steady pace.

Here are some tips that will help you in your work.

Work Pace

• Draw up a study timetable that takes into account your personality andneeds as well as your family, work and other obligations.

• Try to study a few hours per week. You should break up your study timeinto several one- or two-hour sessions.

• Do your best to stick to your study timetable.

Materials

Have all the materials you need close at hand.

• Learning material: this guide, a notebook where you will summarizeimportant concepts relating to the objectives (listed in the introductionto this guide), and the Key Words in Each Chapter supplement in whichyou will define in your own words the boldface terms that appear inthis guide.

• Reference materials: a dictionary, a calculator.

• Miscellaneous material: a pencil for writing your answers and yournotes on this guide, a coloured pencil for correcting your answers, ahighlighter (or a pale-coloured felt pen) to highlight important ideas,an eraser, etc.

• The periodic table of the elements and the experiment kit that camewith this guide.


Learning Activities

This guide includes theoretical sections, as well as practical activitiesin the form of exercises. These exercises come with an answer key. Theguide also includes several experiments involving simple operations thatyou can perform with the experiment kit you received with this guide. Itis important that you take the necessary time to carry out the differentsteps described because they will help you develop a clearer understandingof the theory being presented.

Start by skimming through each part of this guide to familiarizeyourself with the content and main headings. Then read the theorycarefully:

– Highlight the important points.– Take notes in the margins.– Look up new words in the dictionary.– Summarize important passages in your own words, in your

notebook.– Study the diagrams carefully.– In the supplement entitled Key Words in Each Chapter, write your

own definition of the terms that appear in boldface in the text andcompare your definitions with those given in the glossary.

– Write down questions relating to ideas you don't understand.

Experiments

In order to attain the course objectives, you are asked to do a numberof experiments as part of the learning activities. These experiments arecompulsory, which is why you were obliged to purchase an experiment kitwhen you ordered the learning guide. This kit contains several importantitems that are usually hard to obtain. However, you will still have toacquire a number of other items yourself.

• For Experiment 1.1: lemon and apple juice, vinegar, human urine andsaliva samples, tap water, sodium bicarbonate (baking soda), Fantastikcleaner, and either rainwater or melted snow.

• For Experiment 4.1: rubbing alcohol, window cleaner with ammonia,table salt, sugar, vinegar, Fantastik cleaner, and demineralized water.

• For Experiment 6.1: vinegar, Easy-Off oven cleaner (liquid), twoglasses, and two wooden stirrers (coffee stirrers or popsicle sticks).


Exercises

The exercises come with an answer key found in the coloured sectionat the end of this guide, following the self-evaluation section.

• Do all the exercises.

• Read the instructions and questions carefully before writing youranswer.

• Do all the exercises to the best of your ability without looking at theanswer key. Reread the questions and your answers and revise youranswers, if necessary. Then, check your answers against the answerkey and try to understand any mistakes you made.

• Complete a chapter before doing the corresponding review exercises.Doing these exercises without referring to the lesson you have justcompleted is a better way of preparing for the final examination.However, you are not required to memorize dates, numerical data, orresearchers' names. What is important is that you form an overview ofthe subject, that you grasp the connections, and that you develop theability to make sound judgments.

Self-Evaluation Test

The self-evaluation test is a step that prepares you for the finalevaluation. You must complete your study of the course before attemptingto do it. Reread your notebook and the definitions of the key words in eachchapter. Make sure you understand how they relate to the courseobjectives listed in the General Introduction to this guide. Then do the self-evaluation test without referring to the main body of the guide or theanswer key. Compare your answers with those in the answer key andreview any areas you had difficulty with.

Your Tutor

Your tutor is the person who will give you any help you need through-out this course. He or she is available to answer your questions and correctand comment on your homework assignments.

Don't hesitate to contact your tutor if you are having difficulty with thetheory or the exercises, or if you need some words of encouragement tohelp you get through this course. Write out your questions and get in touchwith your tutor during his or her available hours. If necessary, write to himor her. Information about how to contact your tutor that is not alreadycontained in this guide will be made available to you.

Your tutor will guide you in your work and provide you with the advice,constructive criticism and support that will help you succeed in this course.


Homework Assignments

In this course, you will have to do three homework assignments: thefirst after completing Chapters 1 to 4, the second after completingChapters 5 to 7, and the third after completing the self-evaluation test. Inaddition, the final homework assignment may contain questions coveringthe entire course.

These assignments will show your tutor whether you understand thesubject matter and are ready to go on to the next chapter in the course. Ifyour tutor feels you are not ready to move on, he or she will indicate thisin your homework assignment, providing comments and suggestions tohelp you get back on the right track. It is important to read thesecorrections and comments carefully.

You must obtain an average of at least 60% on the three homeworkassignments to be entitled to write the examination that permits you toearn the credits for this course.

The homework assignments are similar to the examination. Since theexam will be supervised and you will not be able to use your notes, the bestway to prepare for it is to do your homework assignments withoutreferring to your learning guide and to take note of your tutor's correctionsso that you can make any necessary adjustments.

Remember not to send in the next assignment until you have receivedthe corrections for the previous one.

Certification

If you obtain an average of at least 60% on your homework assign-ments, you may write the examination that permits you to earn the creditsfor this course. The examination is divided into two parts.

Part I consists of a two-hour written examination made up of multiple-choice, matching, and short-answer questions. This part is worth 76% ofyour final mark. You will be provided with a periodic table that does notinclude the full names of the elements, as well as a list of the names andformulas1 of the main polyatomic ions. You may also use a calculator.

Part II also consists of a written examination, but in the form of one ormore essay questions that allow you to summarize what you have learnedfrom the course in terms of your ability to carry out a case study. Allpertinent information such as numerical data, tables, and referencedocuments will be an integral part of the exam. This second part is worth24% of your final mark and is written in one 90-minute session.

1. The list of these names and formulas is included with the self-evaluation test.


Both parts of the examination will be supervised and you will not beallowed to refer to your course notes.

To earn the credits for this course, you must obtain a total mark of atleast 60% for both parts of the examination. Your homework assignmentswill not count toward your final mark.

Useful Information

Number of credits: 2 credits at the Secondary IV level

Course duration: approximately 50 hours of study

Number of homework assignments: 3

Opportunity to revise and re-submit homework assignments: none

Pass mark: average of 60% on the homework assignments average of 60% on both parts of the final examination


MATHEMATICAL PREREQUISITES

Below is a review of the mathematical prerequisites or concepts thatyou must know in order to work through the module with ease. Read thissection carefully, and if necessary, refer back to it as you work through themodule.

How to Round Off a Number

There are different reasons for rounding off a number to the nearestunit, to the nearest tenth, or to any other place value. To begin with, let'slook at the names of the positions occupied by the digits in a decimalnumber. For example, take the number 35 497.8621. The place values ofits digits are read as follows:

DECIMAL NUMBER 35 497.8621

To round off this number to any place value, use the followingprocedure:

• Identify the digit occupying the position corresponding to the requireddegree of accuracy.

• Identify the first digit to the right of the designated position:– if it is 0, 1, 2, 3 or 4, then the digit in the designated position remains

the same;– if it is 5, 6, 7, 8 or 9, then the digit in the designated position should

be increased by 1.

• All the digits to the right of the designated position:– become zero if they are in the integral part of the number;– disappear if they are in the decimal part of the number.

Integral part{3 5 4 9 7

unitstens

hundredsthousands

ten thousands

Decimal point

Decimal part{

8 6 2 1

thousandthshundredths

tenths

ten thousandths

.


Example

Round off the number 35 497.8621 to the nearest unit, to thenearest tenth and to the nearest hundredth.

• To the nearest unitThe digit 7 is in the unit's place. The first digit to the right of 7is 8; therefore, 7 (in the unit's place) is increased by 1 andbecomes 8. All the other digits to the right of the unit's placedisappear. The result is 35 498.

• To the nearest tenthThe digit 8 is in the first decimal place (the tenths). The firstdigit to the right of 8 is 6; therefore, 8 is increased by 1 andbecomes 9. All the other digits to the right of the tenth's placedisappear. The result is 35 497.9.

• To the nearest hundredthThe digit 6 is in the second decimal place (the hundredths). Thefirst digit to the right of 6 is 2; therefore, 6 does not change. Allthe other digits to the right of the hundredth's place disappear.

The Metric System

Symbols of quantity and their units

The result is 35 497.86.

Quantity Symbol Unit Symbol

Length

Mass

Molar mass

Pressure

Amount of substance

Temperature

Time

Volume

l

m

M

p

n

T or t

t

V

metre

kilogram

kilogram per mole

pascal

mole

kelvin or Celsius

second

litre

m

kg

kg/mol

Pa

mol

K or °C

s

L


Multiples and submultiples of SI units

Here are a few examples of how multiples are used.1 kg = 1000 × 1 g = 1000 g

1 hg = 100 × 1 g = 100 g

1 dag = 10 × 1 g = 10 g

1 dg = 0.1 × 1 g = 0.1 g

1 cg = 0.01 × 1 g = 0.01 g

1 mg = 0.001 × 1 g = 0.001 g

An Important Property of Proportions

In any proportion, the product of the extremes is equal to the productof the means.

Since a proportion consists of two equal ratios, we can say that .

In this case, if 1 and 8 are the extremes, and 2 and 4 are the means, then

1 × 8 = 2 × 4.

This property is extremely useful when we want to convert a quantityexpressed in one unit of measurement to an equivalent quantity expressedin another unit of measurement.

Prefix Symbol Multiplier

Exa-

Peta-

Tera-

Giga-

Mega-

Kilo-

Hecto-

Deca-

Deci-

Centi-

Milli-

Micro-

Nano-

Pico-

Femto-

Atto-

E 1018 =

P 1015 =

T 1012 =

G 109 =

M 106 =

k 103 =

h 102 =

da 101 =

d 10–1 =

c 10–2 =

m 10–3 =

µ 10–6 =

n 10–9 =

p 10–12 =

f 10–15 =

a 10–18 =

1 000 000 000 000 000 000

1 000 000 000 000 000

1 000 000 000 000

1 000 000 000

1 000 000

1 000

100

10

0.1

0.01

0.001

0.000 001

0.000 000 001

0.000 000 000 001

0.000 000 000 000 001

0.000 000 000 000 000 001

12

48

=


Example

Express a 0.5 kg mass in grams.

We know from the preceding Metric System tables that 1 kgcorresponds to 1000 g. We can then ask the following question:

if 1 kg corresponds to 1000 g, then 0.5 kg corresponds to ? g.

We can now state the following proportion:

By applying the property of proportions and solving the equation,we get:

1 kg × ? g = 1000 g × 0.5 kg

? g = 1000 g × 0.5 kg

? g = 500 g

A mass of 0.5 kg is therefore equivalent to 500 g.

Formulas

Writing formulas often involves applying the rules of geometry or thelaws of physics. A formula generally contains several variables joined byan equal (=) sign. We often need to transform formulas in order to solvefor one variable or another. This can be done by applying the rules forsolving equations.

The formula used to determine the volume of a rectangular prismis V = l × w × h, where V is the volume, l the length, w the width and h theheight. By knowing the length, the width and the height, we can determinethe volume. But what formula can we use to determine the height?

Example

Given the formula V = l × w × h, what formula can we use todetermine the height h?

To determine the height, we have to isolate the variable h in theequation. This can be done by dividing both sides of the equationby the same value and then simplifying the resulting equation.

1 kg

0.5 kg

1000 g

? g=

1 kg


V = l × w × h

This gives us the formula h = .

Scientific Notation

With scientific notation, we can express very large or very smallnumbers without using a long, cumbersome series of digits.

Let's first review the notation for different powers of 10.

10 000 = 10 × 10 × 10 × 10 = 104

1000 = 10 × 10 × 10 = 103

100 = 10 × 10 = 102

10 = 10 = 101

1 = 1 = 100

0.1 = 1/10 = 1/101 = 10–1

0.01 = 1/100 = 1/102 = 10–2

0.001 = 1/1000 = 1/103 = 10–3

0.0001 = 1/10 000 = 1/104 = 10– 4

Any given number can be expressed in several ways. For example, thenumber 4560 can be written as follows:

4560 = 4560 × 1 = 4560 × 100

4560 = 456 × 10 = 456 × 101

4560 = 45.6 × 100 = 45.6 × 102

4560 = 4.56 × 1000 = 4.56 × 103

4560 = 0.456 × 10 000 = 0.456 × 104

Scientific notation involves expressing a number as a power of 10multiplied by a number greater than or equal to 1 and less than 10. In theexample above, 4560 can be written as 4.56 × 103 in scientific notation.

Here are some other examples of numbers expressed in scientificnotation.

13 400 000 = 1.34 × 107

1994 = 1.994 × 103

740 = 7.40 × 102

53.004 = 5.3004 × 101

0.5 = 5 × 10–1

0.000 467 = 4.67 × 10– 4

V= l × w × h

l × w

= h

l × w

Vl × w

Vl × w


IONIC PHENOMENA: A STUDY OF AN ENVIRONMENTAL PROBLEM

Throughout history, human beings have always sought to understandthe world around them. Over the centuries, they have learned to make useof the planet's resources. In their quest for knowledge and for control overthe environment, they have developed industry, agriculture, transporta-tion, and medicine, among other accomplishments. Today, we live in anera of science and technology. Breakthroughs in these fields occur almostdaily. One need think only of the great progress made in the field ofinformatics, both in the workplace and in the home; and of the majorstrides taken in medicine and both experimental and applied biotechnol-ogy. Science and technology are changing and shaping our way of lifealmost daily, not to mention our view of the world.

Major progress made in the field of communications also gives anincreasing number of people access to all kinds of information. It isdifficult to avoid the public debates generated by the consequences ofscientific and technological development. We are much more inclinednow to question science-related policies, the consequences of technologi-cal progress such as the squandering of our resources, the deterioration ofour environment, the potential dangers of nuclear generating stations,and the threat of nuclear war. Developments in science and technology, aswell as the interests, values, and social responsibilities of the people(including industrialists, researchers, politicians, and individuals)responsible for such developments, are often targets of criticism.

To make informed judgments, it is important to have a thoroughunderstanding of the scientific principles underlying a given situation,and this often requires a basic knowledge of chemistry. This learning guidelooks at scientific, technological, social, and economic factors that help usto understand the current debates taking place regarding different scien-tific developments and fuelling a process of reflection that can no longerbe avoided. It does this by focusing on a case study that is specificallyrelated to the issue of acid precipitation.

Chapter 1

Poison from the Sky


1. POISON FROM THE SKYChemicals

Water and atmospheric pollution Case study: acid precipitation Introduction

IONIC PHENOMENA:

AS TU

DY

OF

AN ENVIRON MENTAL PROB L

EM 4. NAMING AND CLASSIFYING COMPOUNDS

New nomenclatureTraditional nomenclatureAcids, bases, and saltsElectrolytes and non-electrolytes

2. THE SECRETS OF MATTER

Simplified atomic model Elements Periodic table Major chemical families

3. MATTER IN ACTION

History Ionization Lewis diagram Chemical bonds Electronegativity

5. A MATTER OF CONCENTRATION

Classification of substancesSolutionsConcentrationpHAcid-base indicators

6. NOTHING IS LOST, NOTHING IS GAINED

Balancing equationsStoichiometryAcid-base neutralization

7. CASE STUDY:ACID PRECIPITATION

The problemThe consequencesThe solutions

1.3© SOFAD POISON FROM THE SKY

Many people maintain that the benefits derived from developmentsin the field of chemistry have greatly simplified our daily lives. Cleaningproducts, plastics, paints, and textiles—all products of the chemicalindustry—have become increasingly important in the home. Modernfarmers use synthetic chemicals to increase crop production and livestockproductivity, as well as to protect both crops and animals against variousblights and diseases. Chemical additives are used throughout the foodindustry to conserve food and enhance its appearance. Advances inchemistry also find application in the transportation, metallurgical, andpharmaceutical industries. In fact, modern society would have difficultymanaging without chemistry and its technology. But what price must bepaid for this heavy dependence on chemical products? In what state willour planet be when we hand it over to the next generation? In fact, Gaea1

is in abysmal shape!

We have not inherited the Earth from our parents; rather, we arelending it to our children.(translation)

World Conservation Strategy

Lakes and rivers, both sources of drinking water, are contaminatedas a result of human activity. Industrial and agricultural operations, aswell as municipalities and individuals, often treat our watercourses likeordinary sewers. Nor has the atmosphere been spared: acid rain, thegreenhouse effect, and holes in the ozone layer are now household words.Pollution is a fact, as we are constantly being reminded by newspapers,magazines, radio, and television. It sometimes seems as if the sky is fallingdown on our heads. Worse still, our feeling of powerlessness is at timesequalled only by our ignorance!

Our watercourses are brimming with chemical pollutants. Someof these pollutants, which are persistent to varying degrees, come fromhousehold wastewater and fertilizers. Others, such as heavy metals, pes-ticides, PCBs (polychlorinated biphenyls), and radioactive substances (toname but a few), remain in the aquatic environment for very long periodsof time and are accumulating at an alarming rate. These chemicals areassociated with a decline in the populations of aquatic environments, aswell as with the appearance of deformities and cancers in fish and birdspecies. The white beluga of the St. Lawrence River—now an endangeredspecies—is a case in point. And much could be said about the rising costof treating water to make it fit for human consumption.

1. Gaea was a Greek goddess who personified the Earth, motherhood, and the universalnurturer. By referring to Earth as "Gaea," we are treating our planet as an independentliving being that reacts to the many stresses that we humans inflict upon it.


The holes in the ozone layer are increasing the risk of skin cancer.The greenhouse effect could, according to a number of theories, raise thetemperature of the Earth to the point of causing drought or even floodswhich, followed by the melting of the polar (Arctic) ice cap, could wipeout entire countries.2 Acid rain is responsible for maple tree dieback, thedeterioration of monuments and buildings in cities, as well as thedisappearance of certain life forms in lakes. It is even thought that 80%of the lakes in eastern Canada are acidic or on the way to becoming so.3

Most people agree that we must act, but disagree as to what weshould do. Pollutants have long-term effects, causing problems as theyaccumulate. What measures must be taken and at what cost? Our leaderssit down together to discuss and decide on the best solutions, but for theindividual person, it is not easy to sift through all the information givenby the media. Also, pollution can be discussed from many differentviewpoints, including science and technology, politics, economics, health,ecology, history, and meteorology.

We are a "chemical" society, using hundreds ofchemicals in our normal daily activities: washing, eating,house-cleaning, tending the lawn and garden, and driving.Of the almost 10 million chemicals known today,approximately 100 000 chemicals are used commercially.Over 10 000 new chemicals are created each week.

Most toxic chemicals are discharged directly into ourwatercourses as waste, but many also enter the water aftereveryday use in the home, agriculture, and industry. Theyconstantly change the chemical composition of our waters.One way is seepage: the chemicals soak through the earthinto the groundwater from waste disposal sites andagricultural lands, for example. Another way is runoff: thechemicals are washed into bodies of water from the landwhere they were used or spilled, or from the air into whichthey were emitted.

The chemicals can affect the taste, odour, and colourof water. Fish and wildlife can experience reduced fertility,genetic deformities, immune system damage, increasedincidence of tumours, and death.

Many of the chemicals that enter the water are, evenin minute amounts, toxic to human, plant, and animal life.Pesticides, PCBs, and PSPs (polychlorinated phenols) aretypical examples. Pesticides are used in agriculture,forestry, and homes. PCBs, although no longer used in newinstallations, are still found as insulators in older electricaltransformers, and PSPs can be found in wood preservatives.The very qualities which make them desirable for use—toxicity and persistence, for instance—make them soharmful to the environment.

2. Another theory says that the greenhouse effect would cause a cooling of the Earth, giventhat CO2, one of the gases responsible for this phenomena, reflects the Sun's rays. However,there appears to be a general consensus that an increase in the quantity of carbon dioxidecauses some increase in temperature.

3. For a general idea of the extent of the acid rain problem in Québec at the end of the 1980s,consult the article "Un sucre au goût acide" by G. Parent and J. Lebrun in the April 1988issue of Québec Science, pp. 18–23.

Source : Canada, Environmental Citizenship, Clean water: life depends on it! Freshwater series, A-3, Environment Canada, p. 5.

Toxic chemicals: the legacy of a chemical society


Below are translations of excerpts from French-language media articles dealingwith some of the problems mentioned in the preceding paragraph. Match eachexcerpt with the point(s) of view expressed by the journalist.

A. Scientific and technological E. Ecological

B. Political F. Historical

C. Economic G. Meteorological

D. Medical

Excerpt Point of view

1. In 1986, Sutton had rainfall that was just like applejuice (La Presse, August 1, 1987).

2. Canada must step up its efforts to combat thepollution of the Great Lakes. So says the UnitedStates at the international conference taking placein Montréal (La Presse, May 14, 1993).

3. The earliest alarming observations of theincreasingly acidic precipitation in Europe andeastern North America date back to the 1960s(Pour la science, October 1988).

4. Acid rain can fall many kilometres away from thesources of pollution (Pour la science, October1988).

5. Noranda Mines Ltd. in Noranda, Québec, is one ofthe ten largest producers of sulphur dioxide (SO2) inCanada (The Canadian Consumer, May 1983).

6. Canadians prove the link between the ozone layer andultraviolet radiation (La Presse, November 12, 1993).

7. Acid rain is fast eroding our children's architecturalheritage (La Presse, August 6, 1988).

8. Acid rain would appear to promote colon cancer(La Presse, March 2, 1988).

9. Child demands ban on pesticide use on Île-Bizard(La Presse, October 4, 1993).

10. Both whales and dolphins are endangered species(La Presse, May 17, 1994).

1.1


Using a dictionary, define the word "pollution."

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

The following two questions ask you to use both your intuitionand personal knowledge to come up with possible answers. The answershave not yet been covered in the text. Try to find your own.

Identify one characteristic that is common to all the following phenomena: acidrain, greenhouse effect, holes in the ozone layer, and sources of water pollution.

________________________________________________________________________

________________________________________________________________________

Match each of the phenomena listed in 1.3 with the observations in the left-handcolumn of the table below. Note that, in some cases, more than one phenomenonmay be mentioned.

Observation Phenomenon

Glass or paint that loses its shine

Skin cancer

Automobile exhaust emissions

Increase in ultraviolet radiation

Death of fish in lakes

Maple tree dieback

Global warming

Beach closures

PROBLEMS RELATED TO THE USE OF CHEMICALS

In this guide we will touch on some of the problems related to theuse of chemicals. The different forms of water and atmospheric pollutionare often the consequences of human activity. Pollution is a complexphenomenon, and its impact on the environment, health, and the economyare equally complex. Also, there are as many solutions proposed to theseproblems as there are points of view in the various sectors affected.

1.2

1.4

1.3


In order to clearly pinpoint a problem related to the use ofchemicals, we must examine it from several vantage points: scientific,technological, social, economic, ecological, political, even historical andethical. We are therefore going to develop a strategy for analyzing theseproblems: our strategy will be the case study. However, let us firstexamine the nature of some of the atmospheric and water pollutionproblems we currently face, as well as the causes.

Water Pollution Problems

When we think of life, we immediately think of water. After all,Earth isn't called the "blue planet" for nothing. And didn't life on Earthbegin in water? Even our bodies comprise mostly water. Water coversmuch of our planet, lies underground, and fills the atmosphere. Yetonly a minute portion of this colourless liquid is both drinkable andaccessible.

A Country Built on Water Resources

Our continent was largely colonized by means of its manywatercourses. An ideal means of communication and travel, the GreatLakes, as well as the St. Lawrence River and its many tributaries, lentthemselves to settlement along their shorelines. Agriculture became afact of life along the tributaries of the main rivers. Cities sprang up,bringing with them industry and people. These vast water resources thusfostered and fuelled human activity. Today, such activity still depends onour water resources.

This marked growth in human activity alongside our watercourseshas created its share of problems, however. The Great Lakes, St. LawrenceRiver, and Atlantic Ocean have been unfavourably compared with animmense sewage system. Over the last 100 years, more than60 000 different chemicals have been dumped into the enormous basinformed by the Great Lakes. The St. Lawrence River serves as the primarysewer main for these chemicals and as a recipient for all the toxicpollutants generated by the activities of our neighbours upstream. Intothis toxic stream feeds all the waste produced alongside the river, whichin turn carries it to the vast trunk sewer, the ocean.


Figure 1.1Toxic substances in the aquatic environment

Atmospheric fall-out from different sources contributes to water pollution. Diffusion, bubble transfer, and exchangesbetween ocean-bed sediment and the surface of the water illustrate the different routes taken by pollutants. This pollutionis passed on to all living beings that make up aquatic flora and fauna.

Wet deposition

Dry deposition

Volatilization

AbsorptionBubble transfer

Vertical and horizontal diffusion

Sediment-water diffusion

Suspension

Partitioning in the atmosphere

Diagram adapted from Canada, Environmental Citizenship, Clean water: life depends on it! Freshwater series, A-3,Environment Canada, p. 5.


There are many sources of water contamination, but three typesof human activity are the main sources of the problem: industrial,agricultural, and domestic.

Industrial waste contributes to the accumulation of the most highlytoxic and long-lasting chemicals in our watercourses, such as petroleumproducts, heavy metals (lead, mercury, cadmium), and PCBs. Around theGreat Lakes alone, no fewer than 42 sites have been identified as beinghighly contaminated by such products. This contamination is directlyresponsible for the decline in reproduction and the appearance of muta-tions in the animals affected, for beach closures, and for problems inwater treatment. We are only beginning to recognize the enormity of theenvironmental, economic, and social costs of this contamination.

Agricultural activity also contributes significantly to thedeterioration of our watercourses. Because of its geographic distribu-tion, the principal negative effect of this industry is to contaminate thetributaries of the major watercourses. Fertilizers, pesticides, and theorganic matter found in manure, as well as water from dairies, return tothe watercourses through run-off or leaching.4 Fertilizers foster the growthof algae, and the resulting increase in debris accelerates the aging of lakes.The pesticides in food enter the food chain and are often associated withthe onset of various types of cancer. Organic pollutants promote thegrowth of bacteria and viruses associated with certain health problemsand the closure of public beaches.

Household activities lead to the discharge of mainly organic matterinto the sewage system. Added to this is water from storm drains, whichcontains road maintenance products and other contaminants (petroleumproducts and cleaning products). Lastly, the many chemical products thatwe use on a daily basis join the list of industrial and agricultural pollutantsand contribute to the problems mentioned earlier.

4. The passage from upper to lower soil horizons of certain elements that dissolve in waterand thus percolate down into and contaminate groundwater reserves.


An endangered resource

Whatever we do or wherever we go, water iseverywhere, and, at first glance, seems infinitelyavailable. Covering nearly three-quarters of theEarth's surface in the form of oceans, rivers,streams, lakes, snow, and glaciers, it is also foundin the atmosphere and underground.

It is estimated that the world has water reservestotalling 1386 million km3. Such vast quantities arehard to imagine! To give you an idea of just how muchwater this is, 1 km3 of water would fill 300 Olympicstadiums. Of this quantity, 95.1% takes the form ofsaltwater that is difficult to desalinate for humanconsumption. Freshwater makes up only 4.9% of thetotal volume, and most of this occurs in the form ofice or groundwater, making it virtually inaccessible.Only 139 000 km3 of freshwater do not occur in theform of ice or groundwater. The human race thereforehas only 0.01% (1/100 of 1%) of the total volume ofwater on Earth available to meet its needs. By way ofcomparison, if you could put all the water on ourplanet into a 45-gallon barrel, the portion that wouldbe usable by humans would be less than one teaspoon.

Canada is rightfully famous for its freshwaterreserves. Ask any of the tourists arriving at the airportfor their main impression of Canada, and there's astrong chance that they will talk about its vastexpanses of water. Lakes cover approximately 8% ofthe country's surface area, a proportion that isunmatched anywhere else in the world. Canada has565 lakes with a surface area larger than 100 km2.The Great Lakes alone, which straddle the Canada–U.S. border, contain 22 700 km3 of water, or 25% ofthe freshwater in all the lakes on the planet. They areon par with Lake Baïkal in Siberia in this respect.

It is estimated that 9% of the world's freshwaterreserves are located on Canadian territory, comparedwith 18% in Brazil, 9% in China, and 8% in theUnited States. Canada boasts some 120 000 m3 offreshwater per capita, an enormous figure comparedwith other regions of the world: the island of Malta,for example, has less than 100 m3 of freshwater percapita. Québec shares in Canada's wealth of waterresources, with 10% of its surface area covered byfreshwater.

An illusion of abundance

However, even though Canadians have abundantwater reserves, it is important to realize that most ofthis water is located far from urban, agricultural, andindustrial centres. In fact, two-thirds of Canada'sfreshwater resources flow northward into the basinsof the Arctic Ocean and Hudson Bay, while 90% ofthe population lives within 300 km of the Canada–U.S. border.

It is becoming increasingly difficult to secure ourdrinking water supplies from watercourses owing tothe nature, quantity, and variety of the contaminantsdumped into the environment as the result of urban,industrial, and agricultural activities. The use of new,non-biodegradable chemicals makes any naturalpurification process difficult, if not impossible.

Pollution from acid rain is another cause of thedeterioration in water quality. In Québec, the effectsof acid rain are felt mainly north of the St. LawrenceRiver. Of the 1253 lakes sampled, 50% are acidic orbecoming so. The most drastically affected regionsare the Côte-Nord, Outaouais, Mauricie, and Abitibi.

Source: André Saint-Hilaire, "La qualité de l'eau au Québec," in Protégez-Vous, Cahier spécial H20 (May 1995), pp. 4–5(translation).


Atmospheric Pollution Problems

The main focus of this learning guide will be acid rain, but thisproblem will also be related to other types of atmospheric pollution.Acid rain, the greenhouse effect, and the holes in the ozone layer arethree of the consequences of atmospheric pollution. These phenomenaare not all caused by the same type of polluters, however. We will look atthe nature of each problem and the main polluters associated with it.

The Ozone Layer

The ozone layer of the atmosphere lies at between 15 and35 kilometres of altitude. The ozone it contains protects terrestrial lifefrom the Sun's ultraviolet rays. Formerly, aerosol sprays and certain foamscontained chemical substances known as chlorofluorocarbons, or morecommonly, CFCs. After recognizing the harmful effects of these chemicalson the ozone layer, we cut back on their use, and today their use isrestricted almost exclusively to refrigeration systems. As their nameindicates, they contain chlorine, fluorine, and carbon. Once released intothe atmosphere, CFCs react with the ozone, which gradually disappears.The net result is a thinning of the ozone layer. As this is the layer thatprotects us from ultraviolet radiation, the main consequence of its thinningmay be, according to some scientific researchers, an increase in the inci-dence of skin cancer. The decline in agricultural production and thedeficiencies of the human immune system5 may also be attributable tothe decrease of ozone in the atmosphere. However, nothing is absolutelycertain. Other scientists claim that ultraviolet radiation poses a threat ifwe are exposed too long to the Sun, and that we are wrong to associateskin cancers with the thinning of the ozone layer. Regardless of who isright and given that prevention is better than a cure, alternative solutionshave been found and the consumption of CFCs has continued to declineever since the relationship between CFCs and ozone was first establishedin 1982.

5. The system of reactions of the human body that enable it to resist the invasion of certaindisease-causing agents (bacteria, microbes, viruses).


Figure 1.2Thinning of the ozone layer

Without protection from the ozone layer, swimmers risk "frying" in the sun.

CanadaUnited States

Earth

Ozone

UV radiation


The Greenhouse Effect

Certain gases serve the same function as windows in a greenhouse:they allow light rays in but prevent infrared rays from escaping. The resultis that heat accumulates in the greenhouse. Scientists, notably those atthe Institut de physique de Berne in Switzerland, have successfullydemonstrated that carbon dioxide (CO2) is contributing significantly tothe warming of Earth's climates. This is what is known as the greenhouseeffect. The consequences could be very harmful. The poor countries ofthe Third World risk seeing their already-fragile agricultural lands erodedby global warming and drought. Even water reserves are threatened.Hurricanes could become more severe and occur more frequently.However, scientists are divided in their opinions of the consequences ofthe greenhouse effect. Some think that a portion of the increased carbondioxide would be absorbed by the oceans and that this phenomenon wouldreduce the warming effect on the Earth's climates. One thing is certain,however—the consequences will be most undesirable. The increasedquantities of CO2 in the atmosphere are due mainly to the use of petroleumand its by-products, used mostly in transportation and thermal generatingstations.

Figure 1.3Greenhouse effect

The greenhouse effect could result in global warming.


Acid Rain

In its natural state rainwater is slightly acidic, but this acidityincreases with a rise in atmospheric pollution. Acid rain enters directlyinto the water cycle. Water quality is therefore linked to air quality.Industrial pollution is the main factor responsible for acid rain. The mostharmful wastes emitted into the atmosphere from factory smokestacksare sulphur dioxide (SO2) and the nitrogen oxides (NO2, NO3, and N2O5,usually grouped under the symbol NOx).

Sulphur dioxide (SO2) is produced mainly by metal-processingplants, which treat metals such as copper (Cu), nickel (Ni), lead (Pb), andzinc (Zn). It is also released by thermal generating stations, which produceelectricity through petroleum or coal combustion. The pulp and paperindustry also releases SO2 into the atmosphere, but in smaller quantities.

Figure 1.4Consequences of acid rain

Depending on the region, 40% or more of the nitrogen oxides (NOx)comes from motor vehicle exhaust (cars, airplanes, trains, buses, trucks,boats). The rest is generated through the use of other fossil fuels6 (oil,coal, and natural gas) for the production of electricity, in heating systems,and to provide the energy required for certain industrial processes.

6. Substances formed through the fossilization of organic matter, which when burned andconsumed, produce a quantity of usable energy in the form of heat.

Acid rain has devastating effects on nature.


The pollutants released into the atmosphere by industry are notstatic—they travel. Winds can carry them as far away as 10 000 kilometresbefore they fall to the ground in the form of precipitation. In Canada, it isestimated that the quantity of acid rain caused by pollutant emissionsin the United States is five times greater than that caused by Canadianpollution.

Acid rain has harmful effects on all living things. It affects ourhealth and that of animals, mainly fish, birds, and insects, bycontaminating the water supply. It retards plant growth and makes plantsmore vulnerable to disease. Moreover, it hurts agriculture by depletingthe soil, and erodes materials (for example, metal corrosion, loss oftransparency of glass, increased brittleness of paper over time, and paintdiscoloration).

A number of pollution problems have been mentioned in the preceding pages. InExercise 1.1, you were asked to identify different points of view associated withpollution problems. Now suppose that you have to do a research project on apollution-related problem. Choose one type of problem and list five aspects orgeneral points of view that you would have to cover in order to provide acomprehensive overview of the problem.

Type of pollution problem: ________________________________________________

1st aspect: _____________________________________________________________

2nd aspect: _____________________________________________________________

3rd aspect: _____________________________________________________________

4th aspect: _____________________________________________________________

5th aspect: _____________________________________________________________

You may have found this exercise difficult to do, especially if youlimited yourself to only general aspects; or, you may have had difficultylimiting yourself to only five aspects. In any case, you were lacking aframework—a canvas on which to organize your thoughts. A problemcan, and in fact must, be approached from many different angles.

Water pollution, for example, will affect you differently dependingon whether you work in a "polluting" industry, have family responsibilities,or are a student who is aware of the deterioration in the quality of ourplanet. Regardless of your personal concerns, first and foremost, youshould paint a complete picture of the situation. You should identify theproblem, list the consequences, analyze possible solutions, and take theirimpact into account.

1.5


To form an overview of the problems associated with the use ofchemicals, we propose that you use the case study as your framework.

CASE STUDY

The proposed case-study method lends itself to all types of cases(e.g. student files and legal cases), but it is particularly useful in analyzingenvironmental problems such as acid rain, pesticide use, waste manage-ment, water pollution, or energy resource management.

To do a thorough and complete case study, all facets of theproblem—scientific, technological, historical, political, and economic—must first be identified. Then all the consequences of technologicaldevelopments must be analyzed: this of course means identifying problemsrelated to the use of technology, but even more importantly, situatingtechnology in a broader social context. Lastly, the case study is completedby examining and assessing possible solutions.

The following is a case study carried out by David Suzuki, a well-known Canadian scientist and broadcaster who has brought science withinreach of the English-speaking public. The following short passage from atext entitled Limites de la prévisibilité des effets de la technologie illustratesthe different aspects of a problem related to the use of DDT, a powerfulinsecticide.

Sample case studyThe first example is that of DDT. The advantages of this productwere clear: enormous profits for the chemical industry and pos-session of a non-specific, albeit powerful, means of combattingharmful insects. Moreover, its generalized use saved millions oflives by temporarily reducing the incidence of malaria. However,with even a minimum of reflection, any geneticist or ecologistwould have been able to cast strong doubt a priori on the long-term value of DDT, by predicting that it would also promote theselection of resistant mutants and would cause a majordisruption in ecosystems, owing to its lack of specificity. Onthe other hand, no prior evaluation could have anticipated thephenomenon of biomagnification, that is, the concentration ofcertain substances at the highest levels of the food chain. Thisphenomenon became evident only because DDT came intowidespread use. Consequently, no one could have foreseen thatthis compound would end up being concentrated in the shellsecretion glands of birds, causing eggshells to thin and becomeincreasing fragile, to the point of threatening the very survivalof numerous species.7

7. Taken from Rapport final du colloque de Venise (1986), La science face aux confins de laconnaissance : le prologue de notre passé culturel, Paris: UNESCO (translation). Reproducedwith the permission of UNESCO.


Example

Referring to the preceding text, identify the different aspects ofthe problem of using DDT as an insecticide.

Even though the case study is very short, it touches upon severalof the aspects involved in the problems associated with the use ofDDT.

• Economic aspect

This aspect is underscored from the standpoint of both theproducing industry and the user: major source of revenue forthe manufacturer and effective means of controlling undesirableinsect populations.

• Social aspect

This dimension is presented in terms of the advantages forpublic health: it reduces malaria in poor countries.

• Scientific aspects

These are described in terms of the risks of developing a resistantstrain of insect and DDT's lack of specificity.

• Environmental aspect

This aspect is presented in terms of the various environ-mental consequences: major disruption of ecosystems,biomagnification, thinning of eggshells, and threat to thesurvival of certain species.

• Analysis of solutions

In both its tone and manner of presentation, the text stressesthe major costs (in this case, mostly environmental costs)associated with the apparent short-term advantages of usingDDT, as well as the difficulty or lack of will to foresee theenvironmental consequences of the widespread use of a productsuch as DDT.

Again, even though the sample case study is very short, it bringsout several aspects of the problem. To undertake a more thorough casestudy, it is important to form a broad and informed overview of theproblem involved. It is therefore important to learn to be rigorous in yourwork without getting lost in the details.


Case-Study Outline

To carry out a case study, it is important to adopt a framework foranalysis that is rigorous, but at the same time flexible and adaptable. Thefollowing diagram outlines a general framework that is applicable to alltypes of case studies.

Figure 1.5Case-study outline

Working within a specific framework simplifies the task of carrying out a case study.

Scientific Technological

Defining the problem

Analyzing the solutions

Historicalcontext

Agents responsible

Scientific aspects

Inventory Feasibility andlimitations

Environmental Social Economic Political

Aesthetic Ethical

His

tori

cal

So

cial

Po

liticalE

con

om

ic

Value

Determining the consequences


The above diagram shows three main steps in carrying out a casestudy related to the use of chemicals: defining the problem, determiningthe consequences, and analyzing the solutions.

Defining the Problem

The first step consists in defining the problem. This involvessituating the problem in its historical context, identifying the causes ofthe problem, and lastly, examining the scientific and technologicalaspects of the problem. Once this step has been completed, you are in abetter position to understand the problem and move on to the second step.

Referring to the example involving DDT, it was pointed out thatuse of the product brought with it the risk of encouraging the developmentof resistant strains of insects (in which case the pesticide would nolonger have the effect observed in the initial trials) and of causing a majordisruption in ecosystems, given that DDT did not target any one species.

Determining the Consequences

Again as shown in the diagram on page 1.18, the second stepinvolves drawing up the most complete list possible of the consequencesof the problem. In order to form an overview, the different types ofconsequences of the case under study must be identified: environmental,political, economic, and social.

In the example of DDT, several consequences were specified: thereduction in the incidence of malaria (social aspect), the major revenuesderived by the producing industry and the users (economic aspect), as wellas the threat to the survival of certain species (environmental aspect).

Analyzing the Solutions

The last step involves analyzing the possible solutions to theproblem. This involves making a detailed list of all possible solutions,taking into account their feasibility and limitations. To complete this step,the scientific, technical, social, political, and economic merits of thedifferent solutions proposed must be assessed.

Again referring to the example of DDT, it becomes abundantly clearthat, while the use of DDT provided a short-term solution to the insectproblem, a more in-depth analysis of the long-term consequences wouldhave brought to light several of the harmful effects that later led to a banon the product.

Analyzing the problems related to the use of chemicals is a complexprocess. Often generated by decisions that have more to do with produc-tion and consumption, these problems affect society in various ways. It istherefore important to look at all aspects of a problem to ensure that thecase study is thorough and complete.


Informed choices

No form of energy used by humans is perfect. Car engines burn gasoline, releasing gasesinto the atmosphere; these gases in turn react with rainwater to form acid rain. The sameapplies to coal burned in industry. Other means of producing energy, such as nuclear fission,also exist, each with its own advantages and disadvantages. We can also produce electricityby means of hydroelectric dams. Choices must be made, however, and this is no easy task. Itis therefore important to have a clear understanding of the political, economic, technological,and environmental implications of each option in order to make informed choices.

CASE STUDY: ACID RAIN

We have chosen the topic of acid rain for our case study in thislearning guide. This highly complex problem has an impact on manyaspects of our society. It is also a global problem. Initially generated byatmospheric pollution, by its very nature it also affects the quality of water.In the following pages, we are going to begin our case study of acid rainaccording to the procedure outlined in Figure 1.5. In Chapter 7, we willdo a more in-depth analysis of the problem in light of the knowledge ofchemistry acquired throughout the course.

As mentioned earlier, the first step is to define the problem. Let usfirst explore the scientific aspect of the problem by learning to recognizeacids.

Before you ever heard about acid rain, what did the word "acid" mean to you?

________________________________________________________________________

________________________________________________________________________

How to Recognize Acids

Chemicals can be categorized as either acidic, basic (alkaline), orneutral. Litmus paper, which comes in blue or red strips, can be used todetermine which category a liquid substance falls into. You simply dipthe litmus paper into the liquid and observe if it changes colour.

1.6


Blue litmus paper turns red in the presence of an acid, but staysblue on contact with a base or a neutral solution. In other words, bluepaper serves to identify an acidic solution, but not to distinguish betweena base and a neutral solution. Red litmus paper, on the other hand, turnsblue in the presence of a base, but retains its colour in the presence of anacid or a neutral solution. It clearly identifies a base, but does notdifferentiate between an acid or a neutral solution. In the followingexperiment, you will use both types of litmus paper.

Purpose of the experiment

To distinguish, from among a group of substances, those which are acidic.

Hypothesis

Using what you know about the substances in the following list of requiredmaterials, which would you classify as acidic substances? Enter your predictionsin the second column of the Table of Results shown on the next page.

Required materials

– Blue litmus paper and red litmus paper

– The following substances: lemon juice, apple juice, vinegar, a human urinesample, a human saliva sample, tap water, sodium bicarbonate (baking soda)dissolved in a small quantity of water, Fantastik cleaner, and rainwater ormelted snow

– Other liquids that you would like to analyze (enter them in the spaces providedat the bottom of the Table of Results)

Experiment 1.1One method of recognizing acidic substances

In French, the word for litmus paper is "papier de tournesol." According to popular belief,the indicator known as "tournesol" is extracted from the well-known plant by the same name,tournesol (or "sunflower" in English). Who has not tasted sunflower seeds? Yet nothing couldbe further from the truth. In fact, this indicator is extracted from several species of lichen,the most common being Variolaria lecanora and Variolaria rocella, which have the propertyof changing colour depending on whether the environment is acidic (red) or basic (blue).

English adaptation of Claude Rhéaume's article En quête des phénomènes ioniques, Module 3, Montréal:Éditions HRW (1991), p. 66, with information from the Encyclopædia Britannica (1985) and McGraw-HillDictionary of Scientific and Technical Terms (1989).

Litmus paper


Steps in the experiment

1. Put a small quantity of lemon juice in a dish.

2. Dip one end of the red litmus paper into the liquid and observe what happens.

3. Record any change in colour in the following table.

4. Dip one end of the blue litmus paper into the liquid and observe what happens.

5. Record any change in colour in the following table.

6. Repeat the first five steps in the experiment, each time replacing thelemon juice by one of the other substances listed. If you use the samedish, make sure you rinse and dry it thoroughly before pouring in a newsubstance.

Conclusion

a) Complete the fourth column in the table by writing "acidic" or "non-acidic"beside the name of each substance.

b) Which of the above substances are acidic?

________________________________________________________________________

________________________________________________________________________

c) For which substances did your observations agree with your predictions?

________________________________________________________________________

Table of Results

Substance Prediction

Observations

ResultRed litmus Blue litmus

paper paper

Lemon juice

Apple juice

Vinegar

Urine

Saliva

Tap water

Baking soda, dissolved ina small quantity of water

Fantastik cleaner

Rainwater or melted snow


d) For which substances did your observations not agree with your predictions?

________________________________________________________________________

e) Do the results of your experiment confirm your original hypothesis?

________________________________________________________________________

Litmus paper is not the only indicator of acidity or alkalinity. Tea,for example, is another indicator. Perhaps you have already observed thattea changes colour when you add lemon juice. If you haven't, perform thefollowing experiment: make some hot tea and add several drops of lemonjuice. The change in colour indicates a change in the degree of acidity.Tea thus serves as an indicator of acidity, even though the change is notas evident as it is with litmus paper.

Do you remember the first time you ever heard of acid rain? Approximately howlong ago was it? At that time, did you ever relate it to the acidity of lemon juice orto heartburn?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Let us continue with our case study by putting the problem ofacid precipitation in its historical context and taking a quick look at thestatus of the problem around the world.

Acid Rain: How Long Have We Been Talking about It?

The British chemist Robert Angus Smith is the first person to havedescribed the phenomenon of acid rain. In 1872, in a 600-page text, hedescribed the relationship between industrial emissions and acid pollution.He coined the term "acid rain."

In the early 20th century, it was noticed that trout was mysteriouslydisappearing from various waterways in Norway. Studies showed thatthere was a direct link between the fish mortality and the degree of lakeacidity.

Over the years, the problem was forgotten. But again in 1950, aCanadian ecologist by the name of Eville Gorham became interested inacid raid while studying peat bogs in Great Britain. In an article publishedin 1955, he placed the blame on industry, which he accused of being the

1.7


cause of acid rain. There was little reaction to his article, however. It wasnot until 1961 that a Swede, Svante Oden, again raised the topic of acidrain. Unlike Gorham, his article on the subject attracted the attention ofscientists.

During the 1950s and 1960s, Canadian and Swedish researchersshowed that acid emissions can be transported over great distances bythe wind. The Swede Svante Oden linked the acidity of Scandinavianlakes with high concentrations of air pollutants originating in GreatBritain, Germany, and France. Interest in acid rain grew in the UnitedStates, England, and the U.S.S.R.

The first deliberate measures to limit atmospheric pollution wereintroduced in the 1970s. In 1973, a plan was launched in 11 Europeancountries to measure air pollution over large areas. In 1979, an agree-ment concerning long-range transboundary pollution was signed by35 countries in Geneva, Switzerland.

Even though the majority of scientists have known about the exis-tence of the acid rain problem since the 1950s, it took until the 1980s forthe damage, which was becoming increasingly apparent, to stir publicopinion in any serious way. Many international agreements aimed atreducing atmospheric pollution were signed during that decade.

Over the years, it soon became evident that simply talking aboutacid rain was not enough. There are other forms of precipitation thanrain, whose acidity level can also be high. A more general term wastherefore adopted, and we began to speak of acid precipitation. However,the term "acid rain" is still often used in a generic sense to encompass thesame concepts as the term "acid precipitation."

Do you know of other forms of precipitation than rain that can also be acidic?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Acid Rain around the World

During Prehistory

An American geochemist by the name of Douglas Macdougallbelieves that acid rain may have played a part in the extinction of differentspecies of dinosaurs some 65 million years ago. At that time, acid rainwould not have been caused by industrial pollution as it is today, butrather by a giant meteorite that may have crashed into Earth. This research

1.8


scientist advanced his hypothesis without specifying how a meteorite couldhave caused acid rain. Clearly, it remains only a hypothesis because it hasnot been confirmed.

Figure 1.6An acid meteorite

In Greece

Greece is home to many monuments dating back approximately2500 years to the days of Antiquity. One of the most famous of thesemonuments, the Parthenon, is being eaten away by corrosion. Expertsconfirm that it has been more severely damaged in the last 25 years thanin the preceding 2400 years as a result of the pollution caused by motorvehicle exhaust and industrial emissions.

Also, the Caryatids, six statues of young maidens sculpted in marbleby Phidias at the time the Parthenon was built and that once supportedthe porch section of another Acropolis monument, the Erechthium, hadto be removed to a museum in 1977 and replaced by columns made ofmodern corrosion-resistant materials. The ancient marble from whichthey had been carved was turning to soft gypsum under the action ofatmospheric pollution, especially acid rain.

The acid vapours released by a meteorite may have contributed to the extinction of dinosaurs.


Figure 1.7Historical monuments under attack by acid rain

The world-famous Greek temple, the Parthenon, is rapidly deteriorating under the effects ofacid precipitation.

In the Czech Republic

Several problems have come to light in the Czech Republic.Jean-Marie Pelt, President of the European Institute for Ecology, describesthe situation as follows:

Prague, the Golden City, one of the cradles of Europeancivilization, was only a dozen kilometres off. . . . The road passedthrough a forest, or rather, the remains of a forest. Not a burntforest, not a sick forest, just a dead forest! Kilometre afterkilometre, an endless landscape of dead or dying trees. Then,here and there, a lone survivor with its still-green branches,undoubtedly not for long, seemed to echo the dismay of theseinnocent victims, sacrificed in massive numbers on the altarof acid rain. One last pathetic stand before nature succumbsto death!8

8. Excerpt from the book entitled Le tour du monde d'un écologiste, by Jean-Marie Pelt, Paris:Librairie Arthème Fayard (1990), p. 57 (translation). The author is the President of theEuropean Institute for Ecology. Reproduced with permission from the Librairie ArthèmeFayard, 75, rue des Saints-Pères, 75728 Paris.


Figure 1.8A dead, or dying, forest

In certain forests in the Czech Republic, only a few trees have managed to survive the ravagesof acid rain.

In South Africa

Coal is the main source of energy in South Africa, with 80% of thetotal consumption being burned less than 200 kilometres from the capi-tal, Johannesburg. Very ancient rupestrian9 constructions and paintingsare now in ruins. Kruger National Park is threatened by acid rain as well.

In Canada

The situation in Canada is similar to, perhaps even worse than,that in European countries such as Sweden, Norway, and Finland, withrespect to the contamination of lakes and rivers by acid rain originatingfrom an industrial neighbour to the south. To the southwest of theScandinavian countries, Germany, Poland, and to a lesser extent, GreatBritain operate coal-fired furnaces in factories and plants. To the southwestof Canada, American industries are responsible for polluting theatmosphere. Prevailing southwesterly winds sweep this pollutionnorthward to Canada. While the Swedes have begun to react, mainly byadding lime to lakes to neutralize the acidity, Canada still has a long wayto go in this respect.

9. Rock-hewn or painted on rock.


Figure 1.9Wind transports pollutants

Figure 1.10Regions affected by acid rain in North America

The white areas are minimally affected, the cross-hatched areas aremoderately affected, and the squared areas are severely affected. Notethat the Great Lakes–St. Lawrence Valley region is in the latter category.

a) Prevailing winds in Canada b) Prevailing winds in Scandinavia

Canada

Prevailing winds

Norway

Sweden

Finland

Canada

Minimally affected regions

Moderately affected regions

Severely affected regions


Can you think of other examples close to home or somewhere else in the world,where the environment has been damaged by acid precipitation?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Acid Precipitation: What Is the Situation in Québec?

Québec's 1990 objective was to reduce sulphur dioxide (SO2)emissions—the main cause of acid rain—by 45% relative to 1980 levels.It not only achieved but surpassed this objective, bringing levels downby 65%. Thanks to agreements signed between Canada and theUnited States, it is thought that acid rain will be virtually eliminatedby the year 2000.

Is It Possible to Reduce Acid Precipitation?

During the 1980s, under pressure from environmentalists,governments began to act. Reducing the acidity of rain requires action atseveral levels. As pollutants know no boundaries, they travel from countryto country before falling again in the form of precipitation. Internationalagreements are therefore vital. At the political level, the governments ofmany countries must negotiate and reach agreements. Also, in order forindustries to begin developing less polluting industrial processes, it isimportant to clearly define the problems to be tackled. Today, solutionsdo exist and a number of industries are starting to give priority to lesspolluting technologies. The catalytic converters installed in cars are onesuch example.

Understanding the Nature of Acid Precipitation

To clearly understand the causes and effects of atmospheric pollu-tion, it is essential to know which elements are present in the atmosphereand how they react with one another. Chemistry gives us a scientificunderstanding of acid rain. Moreover, since the pollutants that cause acidrain travel and react with the water in the atmosphere, we also need toknow a few basic meteorological concepts and to understand the dynamicsof nature's water cycle.

1.9


In order to complete the first step in the case study, we must exa-mine the scientific aspects of the question in greater depth. We aretherefore going to explore a little chemistry, as well as the structure ofmatter, the composition of substances and their categories, and the na-ture of acidic and basic solutions. In Chapter 7, we will pursue the casestudy in the light of the knowledge acquired through the course.


Key Wordsin this Chapter

Acid precipitation

Acid rain

Atmospheric pollution

Case study

Greenhouse effect

Ozone layer

Pollution

SummaryThe question of the problems associated with the use of chemicals

can be examined from different angles: science, technology, politics,economy, health, ecology, and history.

We depend on water and air for our survival and that of our planet.The pollution of watercourses is a direct consequence of the humanactivity associated with industry, agriculture, and daily life. Many of thechemicals generated by this activity end up in our watercourses, causingdangerous levels of contamination. Acid rain, the greenhouse effect,and the holes in the ozone layer are three consequences of atmosphericpollution, but unlike the latter two, acid raid enters into the water cycle.

In order to form a general overview of the problems related to theuse of chemicals, we can carry out a case study. Three important stepsare required to analyze a problem efficiently: defining the problem,determining the consequences, and analyzing the solutions. For a casestudy to be valid, it must take into account all aspects of a problem(scientific, technical, social, political, and economic).

The term "acid rain" was first used by the Englishman Robert Smithin 1872. Scientists from many countries became interested in the problemstarting in the 1950s. Several international agreements aimed at reducingacid rain were signed in the 1980s.

When the term "acid rain" is used in the generic sense, it includesthe concepts of dry deposition, fog, snow, hail, dew, cloud, and sleet. It isalso correct to speak of acid precipitation in this broad sense.

In order to reduce acid rain, we must understand its nature. Thisin turn requires a knowledge of chemistry and meteorology.


1.10

Review Exercises

What are the main problems associated with the use of chemicals?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

What are the main sources of water pollution?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

What are the three main types of human activity related to water pollution?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

What are the consequences of water pollution associated with:

a) industrial activity?

________________________________________________________________________

________________________________________________________________________

b) agricultural activity?

________________________________________________________________________

________________________________________________________________________

c) household activity?

________________________________________________________________________

________________________________________________________________________

1.11

1.12

1.13


What are the main pollutants associated with acid rain, the greenhouse effect,and the holes in the ozone layer? In each case, give the main source of thesepollutants.

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Give three consequences of atmospheric pollution.

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Identify one of the things that happens to acid rain after it has formed.

________________________________________________________________________

List some of the different points of view from which the problems related to theuse of chemicals can be examined.

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

What is the main objective of a case study and what must you do to achieve it?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

List the three main steps in a case study.

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

1.14

1.15

1.16

1.17

1.18

1.19


1.20

1.21

1.22

1.23

1.24

1.25

1.26

1.27

What is litmus paper used for?

________________________________________________________________________

What does the generic term "acid precipitation" refer to?

________________________________________________________________________

When was the term "acid rain" first used? Who coined the term?

________________________________________________________________________

When did the term "acid rain" come into use in the media?

________________________________________________________________________

________________________________________________________________________

Give some examples of problems caused by acid rain.

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Why does the fight against acid precipitation require so many international agree-ments?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Why is a knowledge of chemistry needed to understand the nature of acid rain?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Why is a knowledge of certain meteorological concepts needed to understandthe problem of acid rain?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Ionic Phenomena: A Study - Sofad

Documents

Transcript of Ionic Phenomena: A Study - Sofad