Asam Nitrat Dan Fosfat

8/19/2019 Asam Nitrat Dan Fosfat

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C. ASAM NITRAT

Asam nitrat (H NO3), dikenal juga sebagai aqua fortis dan spirit of niter,

merupakan highly corrosive mineral acid !sam nitrat murni tidak ber"arna

(colorless) ,tapi jika disimpan lama akan berubah menjadi kekuningan karena

asam nitrat akan terdekomposisi menjadi o#ides of nitrogen dan air $onsentrasi

asam nitrat yang banyak diperjualbelikan adalah %&' ika asam nitat memiliki

konsentrasi lebih dari %&' disebut fuming nitric acid ntuk asam nitrat

dengan konsentrasi lebih dari *+', asam nitrat diklasifikasikan sebagai "hite

fuming nitric acid or red fuming nitric tergantung jumlah nitrogen dio#ide acid,

!sam nitrat merupakan reagenreaktanagents yang utama untuk proses nitrasi,

yaitu penambahan gugus nitronitro group, pada organic molecule -eberapa

senya"a organik.nitro memiliki sifat /hock.thermally.sensitive e#plosives,

beberapa bersifat stabil digunakan amunisimesiu dan beberapa yang lebih stabil

used as pigments in inks and dyes Nitric acid is also commonly used as a strong

o#idi0ing agent

!plikasi penggunaan utama asam nitrat adalah untuk produksi fertili0ers !samnitrat direaksikan dengan ammonia akan menghasilkan ammonium nitrat 1his

application consumes 2+&4' of the 5%6 tons produced annually (7*&2)

!plikasi lain adalah untuk produksi bahan peledak, nylon dan beberapa

senya"a organik !sam nitrat digunakan juga sebagai senya"a intermediat

untuk industri polimer, seperti polyamides dan polyurethanes

http://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Nitratehttp://en.wikipedia.org/wiki/Nitratehttp://en.wikipedia.org/wiki/Aqua_fortishttp://en.wikipedia.org/wiki/Niterhttp://en.wikipedia.org/wiki/Corrosivehttp://en.wikipedia.org/wiki/Mineral_acidhttp://en.wikipedia.org/wiki/Nitrogen_oxidehttp://en.wikipedia.org/wiki/White_fuming_nitric_acidhttp://en.wikipedia.org/wiki/White_fuming_nitric_acidhttp://en.wikipedia.org/wiki/Red_fuming_nitric_acidhttp://en.wikipedia.org/wiki/Nitro_grouphttp://en.wikipedia.org/wiki/Organic_moleculehttp://en.wikipedia.org/wiki/Explosivehttp://en.wikipedia.org/wiki/Oxidizing_agenthttp://en.wikipedia.org/wiki/Oxidizing_agenthttp://en.wikipedia.org/wiki/Fertilizerhttp://en.wikipedia.org/wiki/Nitratehttp://en.wikipedia.org/wiki/Aqua_fortishttp://en.wikipedia.org/wiki/Niterhttp://en.wikipedia.org/wiki/Corrosivehttp://en.wikipedia.org/wiki/Mineral_acidhttp://en.wikipedia.org/wiki/Nitrogen_oxidehttp://en.wikipedia.org/wiki/White_fuming_nitric_acidhttp://en.wikipedia.org/wiki/White_fuming_nitric_acidhttp://en.wikipedia.org/wiki/Red_fuming_nitric_acidhttp://en.wikipedia.org/wiki/Nitro_grouphttp://en.wikipedia.org/wiki/Organic_moleculehttp://en.wikipedia.org/wiki/Explosivehttp://en.wikipedia.org/wiki/Oxidizing_agenthttp://en.wikipedia.org/wiki/Oxidizing_agenthttp://en.wikipedia.org/wiki/Fertilizerhttp://en.wikipedia.org/wiki/Hydrogen


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Figure 1 Uses of nitric acid.

Precursor to organic nitrogen compounds

8ada industri sintetis senya"a organik, gugus nitro pada asam nitrat merupakan

gugus yang sangat reaktif 6ost derivatives of aniline are prepared via nitration

of aromatic compounds follo"ed by reduction Nitrations entail combining

nitric and sulfuric acids to generate the nitronium ion, "hich electrophilically

reacts "ith aromatic compounds such as ben0ene 6any e#plosives, eg 1N1,

are prepared in this "ay

Rocket propellant

Nitric acid has been used in various forms as the o#idi0er in liquid.fueled

rockets 1hese forms include red fuming nitric acid, "hite fuming nitric acid,

mi#tures "ith sulfuric acid, and these forms "ith H9 inhibitor :;9N!

(inhibited red fuming nitric acid) "as one of 3 liquid fuel components for

the -O6!;


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Woodworking

:n a lo" concentration (appro#imately 74'), nitric acid is often used to

artificially age pine and maple 1he color produced is a grey.gold very muchlike very old "a# or oil finished "ood ("ood finishing),

Etchant and cleaning agent

1he corrosive effects of nitric acid are e#ploited for a number of specialty

applications, such as pickling stainless steel ! solution of nitric acid, "ater and

alcohol, Nital, is used for etching of metals to reveal the microstructure :/O7=74= is one of the standards detailing this "ell kno"n procedure


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Other names

Aqua fortis, Spirit of niter, Eau forte, Hydrogen nitrate, Acidum

nitricum

Properties

Moecuar

formua

HNO!

Moar mass "!#$% g&mo'%

Appearance Cooress iquid

(ensity %#)%*+ g cm'!

Meting point '* -C .' -/0 *!% 12

3oiing point 4! -C .%4% -/0 !)" 12 "45 soution 6ois at

%*% -C .*)$ -/0 !+ 12

Sou6iity in 7ater Competey misci6e

Acidity .pK a2 8%#9%:

;efracti .%"#) -C2

(ipoe moment *#%> ? $#$* (

Thermochemistry

Std moar

entropy .S o*+42

%" @&mo'%&1'%9*:

Std enthapy of

formation .f H o*+42

'*$> B@&mo'%9*:

Hazards

MS(S ICSC $%4!

PCD Safety e6site

EU Inde= $$>8$$8$$8%

http://en.wikipedia.org/wiki/Etchinghttp://en.wikipedia.org/wiki/Etchinghttp://en.wikipedia.org/wiki/Molecular_formulahttp://en.wikipedia.org/wiki/Molecular_formulahttp://en.wikipedia.org/wiki/Molar_masshttp://en.wikipedia.org/wiki/Densityhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Aqueous_solutionhttp://en.wikipedia.org/wiki/Acid_dissociation_constanthttp://en.wikipedia.org/wiki/Refractive_indexhttp://en.wikipedia.org/wiki/Refractive_indexhttp://en.wikipedia.org/wiki/Refractive_indexhttp://en.wikipedia.org/wiki/Dipole#Molecular_dipoleshttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/MSDShttp://www.inchem.org/documents/icsc/icsc/eics0183.htmhttp://msds.chem.ox.ac.uk/NI/nitric_acid.htmlhttp://en.wikipedia.org/wiki/Etchinghttp://en.wikipedia.org/wiki/Molecular_formulahttp://en.wikipedia.org/wiki/Molecular_formulahttp://en.wikipedia.org/wiki/Molar_masshttp://en.wikipedia.org/wiki/Densityhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Aqueous_solutionhttp://en.wikipedia.org/wiki/Acid_dissociation_constanthttp://en.wikipedia.org/wiki/Refractive_indexhttp://en.wikipedia.org/wiki/Refractive_indexhttp://en.wikipedia.org/wiki/Dipole#Molecular_dipoleshttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/MSDShttp://www.inchem.org/documents/icsc/icsc/eics0183.htmhttp://msds.chem.ox.ac.uk/NI/nitric_acid.html


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EU cassification

C O

;8phrases ;4 ;!)

S8phrases .S%F*2 S*! S*" S!" S)

N/PA >$

$

$

OG

Related compounds

Other anions Nitrous acid

Other cations Sodium nitrate

Potassium nitrate

Ammonium nitrate

;eated

compounds

(initrogen pento=ide

E=cept 7here noted other7ise, data is gi> -/2, %$$ BPa2

Safety

http://en.wikipedia.org/wiki/Dangerous_Substances_Directive_(67/548/EEC)http://en.wikipedia.org/wiki/List_of_R-phraseshttp://en.wikipedia.org/wiki/R8:_Contact_with_combustible_material_may_cause_firehttp://en.wikipedia.org/wiki/R8:_Contact_with_combustible_material_may_cause_firehttp://en.wikipedia.org/wiki/R35:_Causes_severe_burnshttp://en.wikipedia.org/wiki/List_of_S-phraseshttp://en.wikipedia.org/wiki/(S1/2):_Keep_locked_up_and_out_of_the_reach_of_childrenhttp://en.wikipedia.org/wiki/(S1/2):_Keep_locked_up_and_out_of_the_reach_of_childrenhttp://en.wikipedia.org/wiki/S23:_Do_not_breathe_gas/fumes/vapour/spray_(appropriate_wording_to_be_specified_by_the_manufacturer)http://en.wikipedia.org/wiki/S26:_In_case_of_contact_with_eyes,_rinse_immediately_with_plenty_of_water_and_seek_medical_advicehttp://en.wikipedia.org/wiki/S26:_In_case_of_contact_with_eyes,_rinse_immediately_with_plenty_of_water_and_seek_medical_advicehttp://en.wikipedia.org/wiki/S26:_In_case_of_contact_with_eyes,_rinse_immediately_with_plenty_of_water_and_seek_medical_advicehttp://en.wikipedia.org/wiki/S36:_Wear_suitable_protective_clothinghttp://en.wikipedia.org/wiki/S45:_In_case_of_accident_or_if_you_feel_unwell_seek_medical_advice_immediately_(show_the_label_where_possible)http://en.wikipedia.org/wiki/S45:_In_case_of_accident_or_if_you_feel_unwell_seek_medical_advice_immediately_(show_the_label_where_possible)http://en.wikipedia.org/wiki/NFPA_704http://en.wikipedia.org/wiki/NFPA_704#Redhttp://en.wikipedia.org/wiki/NFPA_704#Bluehttp://en.wikipedia.org/wiki/NFPA_704#Yellowhttp://en.wikipedia.org/wiki/NFPA_704#Whitehttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Nitrous_acidhttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Sodium_nitratehttp://en.wikipedia.org/wiki/Potassium_nitratehttp://en.wikipedia.org/wiki/Ammonium_nitratehttp://en.wikipedia.org/wiki/Dinitrogen_pentoxidehttp://en.wikipedia.org/wiki/Standard_statehttp://en.wikipedia.org/wiki/Standard_statehttp://en.wikipedia.org/wiki/Dangerous_Substances_Directive_(67/548/EEC)http://en.wikipedia.org/wiki/List_of_R-phraseshttp://en.wikipedia.org/wiki/R8:_Contact_with_combustible_material_may_cause_firehttp://en.wikipedia.org/wiki/R35:_Causes_severe_burnshttp://en.wikipedia.org/wiki/List_of_S-phraseshttp://en.wikipedia.org/wiki/(S1/2):_Keep_locked_up_and_out_of_the_reach_of_childrenhttp://en.wikipedia.org/wiki/S23:_Do_not_breathe_gas/fumes/vapour/spray_(appropriate_wording_to_be_specified_by_the_manufacturer)http://en.wikipedia.org/wiki/S26:_In_case_of_contact_with_eyes,_rinse_immediately_with_plenty_of_water_and_seek_medical_advicehttp://en.wikipedia.org/wiki/S36:_Wear_suitable_protective_clothinghttp://en.wikipedia.org/wiki/S45:_In_case_of_accident_or_if_you_feel_unwell_seek_medical_advice_immediately_(show_the_label_where_possible)http://en.wikipedia.org/wiki/NFPA_704http://en.wikipedia.org/wiki/NFPA_704#Redhttp://en.wikipedia.org/wiki/NFPA_704#Bluehttp://en.wikipedia.org/wiki/NFPA_704#Yellowhttp://en.wikipedia.org/wiki/NFPA_704#Whitehttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Nitrous_acidhttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Sodium_nitratehttp://en.wikipedia.org/wiki/Potassium_nitratehttp://en.wikipedia.org/wiki/Ammonium_nitratehttp://en.wikipedia.org/wiki/Dinitrogen_pentoxidehttp://en.wikipedia.org/wiki/Standard_state


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Second degree burn caused by nitric acid

Nitric acid is a corrosi


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Commerciay a$5 HNO!# he density of

concentrated nitric acid is %#* gFmD#

Contamination with nitrogen dio!ide

http://en.wikipedia.org/wiki/Azeotropehttp://en.wikipedia.org/wiki/Azeotropehttp://en.wikipedia.org/wiki/Azeotropehttp://en.wikipedia.org/wiki/Azeotrope


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Fuming nitric acid contaminated with yellow nitrogen dioxide.

Nitric acid is subject to thermal or light decomposition:

4 HN! " # H# $ 4 N# $ #. %his reaction may gi&e rise to

some non'negligible &ariations in the &apor pressure abo&e the

li(uid because the nitrogen oxides produced dissol&e partly orcompletely in the acid.

%he nitrogen dioxide )N#* remains dissol&ed in the nitric acid

coloring it yellow or e&en red at higher temperatures. +hile the

pure acid tends to gi&e o, white -umes when exposed to air

acid with dissol&ed nitrogen dioxide gi&es o, reddish'brown

&apors leading to the common name /red -uming acid/ or

/-uming nitric acid/ 0 the most concentrated -orm o- nitric acid

at 1tandard %emperature and Pressure )1%P*. Nitrogen oxides

)N x * are soluble in nitric acid.Fuming nitric acid 2 commercial grade o- -uming nitric acid contains 35

HN! and has a density o- 6.7 g8m9. %his grade is much used

in the explosi&es industry. t is not as &olatile nor as corrosi&e

http://en.wikipedia.org/wiki/Nitrogen_dioxidehttp://en.wikipedia.org/wiki/Thermalhttp://en.wikipedia.org/wiki/Nitrogen_dioxidehttp://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressurehttp://en.wikipedia.org/wiki/Nitrogen_oxidehttp://en.wikipedia.org/wiki/Nitrogen_dioxidehttp://en.wikipedia.org/wiki/Thermalhttp://en.wikipedia.org/wiki/Nitrogen_dioxidehttp://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressurehttp://en.wikipedia.org/wiki/Nitrogen_oxide


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as the anhydrous acid and has the approximate concentration

o- #6.4 molar.Red -uming nitric acid or RFN2 contains substantial (uantities

o- dissol&ed nitrogen dioxide )N#* lea&ing the solution with areddish'brown color. ;ue to the dissol&ed nitrogen dioxide the

density o- red -uming nitric acid is lower at 6.43 g8m9.2n inhibited -uming nitric acid )either +FN2 or RFN2* can be

made by the addition o- .< to .=5 hydrogen >uoride )HF*.

%his >uoride is added -or corrosion resistance in metal tanks.

%he >uoride creates a metal >uoride layer that protects the

metal.Anhydrous nitric acid +hite -uming nitric acid pure nitric acid or +FN2 is &ery close

to anhydrous nitric acid. t is a&ailable as 33.35 nitric acid by

assay. ne speci?cation -or white -uming nitric acid is that it

has a maximum o- #5 water and a maximum o- .75 dissol&ed

N#. 2nhydrous nitric acid has a density o- 6.76! g8m9 and hasthe approximate concentration o- #4 molar. 2nhydrous nitric

acid is a colorless mobile li(uid with a density o- 6.76# g8cm!

which solidi?es at @4# AB to -orm white crystals. 2s it

decomposes to N# and water it obtains a yellow tint. t boils

at C! AB. t is usually stored in a glass shatterproo- amber

bottle with twice the &olume o- head space to allow -or pressure

build up. +hen recei&ed the pressure must be released and

repeated monthly until ?nished.

Reactions with metals

Nitric acid reacts 7ith most metas 6ut the etais depend on the

concentration of the acid and the nature of the meta# (iute nitric acid

6eha


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metas# Magnesium, manganese and inc i6erate H*# Others gi


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3eing a po7erfu o=idiing acid, nitric acid reacts


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• e=cess air

• a catayst

•as high a temperature as is consistent 7ith practica6e reactionrates, catayst efficiency and operating pressure

Most pants operate 7ithJ

• moderate pressures .%$8%! atm2

• o=ygen .air2

• an aoy of patinum and rhodium as catayst

• temperatures at %*$$ 1

he main ad


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Figure 2 A gauze of a platinum-rhodium alloy installed in a conerter.

By kind permission of Johnson Matthey.

;hodium is added to the patinum to gi


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o


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In processes 7here significant NOG remains in the gaseous effuent,the effuent is passed through a catayst .patinum or rhodium on asiicoauminate, titanium or


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Pen#elasan lain $

Commercia grade nitric acid soutions are usuay 6et7een )*5 and"45 nitric acid# Production of nitric acid is


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process, aso Bno7n as the arc process# his process is 6ased upon theo=idation of atmospheric nitrogen 6y atmospheric o=ygen to nitrico=ide at


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b) penyerapan nitrogen oksida yang dihasilkan

(!) Oksidasi amonia

:ni bagian dari proses yang melibatkan oksidasi amonia menjadi nitrogen monoksida (nitric

o#ide)>

$ondisi menguntungkan pembentukan produk pada tingkat reaksi yang cocok untuk reaksi

adalah>

? tekanan tinggi

? udara berlebih

? katalis

? suhu setinggi konsisten dengan laju reaksi praktis, efisiensi katalis dan tekanan operasi

$ebanyakan tanaman beroperasi dengan>

? tekanan sedang (74.73 atm)

? oksigen (udara)

? paduan platina dan rhodium sebagai katalis? suhu pada 7544 $

$euntungan utama dari tekanan tinggi adalah bah"a hal itu secara substansial mengurangi

ukuran peralatan dan pipa yang dibutuhkan, dan karenanya mengarah ke biaya modal

berkurang

-ila memungkinkan, amonia dibuat di situs yang sama Hal ini disaring untuk menghilangkan

kotoran apapun dan kemudian dicampur dengan udara terkompresi disaring untuk

memberikan campuran yang mengandung sekitar 74' amonia dan *4' udara 8roporsi yang

tepat dari udara berlebih tergantung pada tekanan operasi dan suhu tanaman


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8era"atan harus diambil untuk meminimalkan oksidasi amonia menjadi nitrogen dengan

lebih eksotermis reaksi, disukai oleh tekanan tinggi dan lebih.dipanaskan katalis

ditingkatkan Oleh 1ekanan 1inggi Ban katalis Cang di atas api

@as panas meninggalkan konverter digunakan baik untuk meningkatkan superheated steam

atau panas gas buang dari menara absorpsi (s) uap yang dapat digunakan untuk

menghasilkan listrik di turbin uap yang kemudian dapat mendorong kompresor udara (s)

@as panas meninggalkan penggalangan uap bagian pertukaran panas pada sekitar =5+ $

(-) 8enyerapan nitrogen oksida

@as selanjutnya didinginkan, di ba"ah 37+ $

!ir ditambahkan dan gas dikompresi lagi (2.75 atm biasanya) suhu naik sampai sekitar =3+

$ dan memerlukan pendinginan lebih lanjut untuk sekitar 374 $ tambahan kompresi dan

bantuan pendinginan reaksi, bergerak kesetimbangan berikut ke kanan>

@as kemudian mele"ati satu atau lebih menara untuk memenuhi aliran air, biasanya mengalir

ke arah yang berla"anan untuk gas Bi sini, oksidasi dari nitrogen monoksida terus dan

penyerapan terjadi dengan pembentukan asam nitrat>

@ambar = /etelah reaksi antara amonia dan oksigen (udara) adalah melanjutkan pada kasa

katalitik, yang e#othermicity reaksi menopang suhu dan paduan logam bersinar merah

:0in jenis ohnson 6atthey

Balam proses di mana NOD signifikan tetap dalam limbah gas, limbah dile"atkan melalui

katalis (platinum atau rhodium pada silicoaluminate, titanium atau senya"a vanadium)

dengan bahan bakar, seperti hidrogen atau metana Oksida nitrogen dikurangi untuk nitrogen

/ebagai contoh>

/uhu di mana reaksi adalah yang paling efektif tergantung pada bahan bakar Hidrogen, itu

adalah =+4 $ untuk metana, adalah muchhigher 2+4 $

!sam dari menara absorpsi mengandung biasanya +%.%4' asam nitrat oleh massa tetapi

dapat diproduksi hingga ca %&' oleh massa -eberapa asam **' diperlukan untuk

pembuatan, misalnya, organik nitro.senya"a untuk bahan peledak dan industri pe"arna

asam nitrat dan air membentuk campuran a0eotropik, dengan titik didih maksimum 3*+ $,

yang mengandung ca %&' asam nitrat massaE sehingga asam pekat tidak dapat diperoleh


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dengan distilasi larutan air asam sulfat pekat digunakan untuk menyerap kadar air dan

kemudian pada distilasi campuran ini, asam nitrat terkonsentrasi diperoleh asam nitrat murni

mendidih pada 3+* $

8enjelasan Fain>

larutan asam kelas nitrat komersial biasanya antara +5' dan %&' asam nitrat 8roduksi asam

nitrat adalah melalui proses Ost"ald, dinamai kimia"an erman Gilhelm Ost"ald Balam

proses ini, amonia anhidrat teroksidasi untuk oksida nitrat, dengan adanya platinum atau

rodium kasa pada suhu tinggi sekitar +44 $ dan tekanan * bar

= NH3 (g) + O5 (g) I = NO (g) % H5O (g) (JH K .*4+,5 k)

Nitrat oksida kemudian direaksikan dengan oksigen di udara untuk membentuk nitrogen

dioksida

5 NO (g) O5 (g) I 5 NO5 (g) (JH K .77= k mol)

Hal ini kemudian diserap dalam air untuk membentuk asam nitrat dan oksida nitrat

3 NO5 (g) H5O (l) I 5 HNO3 (aq) NO (g) (JH K .772 k mol)

Oksida nitrat bersepeda kembali untuk reoksidasi !tau, jika langkah terakhir dilakukan di

udara>= NO5 (g) O5 (g) 5 H5O (l) I = HNO3 (aq)

1he HNO3 encer yang diperoleh dapat terkonsentrasi dengan distilasi sampai sekitar %&'

oleh massa konsentrasi lebih lanjut untuk *&' dapat dicapai dengan dehidrasi dengan

H5/O= pekat Bengan menggunakan amonia yang berasal dari proses Haber, produk akhir

dapat dihasilkan dari nitrogen, hidrogen, dan oksigen yang berasal dari udara dan gas alam

sebagai satu.satunya bahan baku

/ebelum pengenalan proses Haber untuk produksi amoniak pada tahun 7*73, asam nitrat

diproduksi menggunakan proses -irkeland.Lyde, juga dikenal sebagai proses busur 8rosesini didasarkan pada oksidasi nitrogen atmosfer oleh oksigen atmosfer menjadi oksida nitrat

pada suhu yang sangat tinggi -usur listrik digunakan untuk memberikan suhu tinggi, dan

hasil hingga =' nitrat oksida diperoleh Oksida nitrat didinginkan dan teroksidasi oleh

oksigen atmosfer yang tersisa untuk nitrogen dioksida, dan ini kemudian diserap dalam asam

nitrat encer 8roses ini sangat energi intensif dan dengan cepat terlantar akibat proses Ost"ald

sekali amonia murah menjadi tersedia

sintesis laboratorium


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Bi laboratorium, asam nitrat dapat dibuat oleh dekomposisi termal tembaga (::) nitrat,

menghasilkan nitrogen dioksida dan oksigen gas, yang kemudian mele"ati air untuk

menghasilkan asam nitrat

5


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Figure 1 Uses of phosphoric acid.

hie /igure % sho7s the 7ord7ide uses of phosphoric acid, theproportion


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1he conjugate base of phosphoric acid is the dihydrogen phosphate ion,

H58O=., "hich in turn has a conjugate base of hydrogen phosphate, H8O=.5,

"hich has a conjugate base of phosphate, 8O=.3

:n addition to being a chemical reagent, phosphoric acid has a "ide variety of

uses, including as a rust inhibitor, food additive, dental and orthop(a)edic

etchant, electrolyte, flu#, dispersing agent, industrial etchant, fertili0er

feedstock, and component of home cleaning products

1he most common source of phosphoric acid is an &+' aqueous solutionE such

solutions are colourless, odourless, and non.volatile 1he &+' solution is arather viscous, syrupy liquid, but still pourable -ecause it is a concentrated

acid, an &+' solution can be corrosive, although nonto#ic "hen diluted

-ecause of the high percentage of phosphoric acid in this reagent, at least some

of the orthophosphoric acid is condensed into polyphosphoric acids 9or the

sake of labeling and simplicity, the &+' represents H38O= as if it "ere all

orthophosphoric acid Bilute aqueous solutions of phosphoric acid e#ist in the

ortho. form

Phosphoric acid

Names

IUPAC names

http://en.wikipedia.org/wiki/Conjugate_acidhttp://en.wikipedia.org/wiki/Phosphate#Chemical_propertieshttp://en.wikipedia.org/wiki/Phosphate#Chemical_propertieshttp://en.wikipedia.org/wiki/Phosphatehttp://en.wikipedia.org/wiki/Aqueoushttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Volatility_(chemistry)http://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Corrosivehttp://en.wikipedia.org/wiki/Polyphosphoric_acidhttp://en.wikipedia.org/wiki/Chemical_nomenclaturehttp://en.wikipedia.org/wiki/Conjugate_acidhttp://en.wikipedia.org/wiki/Phosphate#Chemical_propertieshttp://en.wikipedia.org/wiki/Phosphate#Chemical_propertieshttp://en.wikipedia.org/wiki/Phosphatehttp://en.wikipedia.org/wiki/Aqueoushttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Volatility_(chemistry)http://en.wikipedia.org/wiki/Liquidhttp://en.wikipedia.org/wiki/Corrosivehttp://en.wikipedia.org/wiki/Polyphosphoric_acidhttp://en.wikipedia.org/wiki/Chemical_nomenclature


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trihydro=idoo=idophosphorus

phosphoric acid

Other names

Orthophosphoric acid

trihydro=yphosphine o=ide

Properties

Moecuar formua H!OP

Moar mass +4#$$ g&mo'%

Appearance 7hite soid or coouress,


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Acidity .pK a2 % *#%4

* >#%+4

! %*#!%+

;efracti cP .%$$52

Structure

Crysta structure monocinic

Thermochemistry

Std moar

entropy .S o*+42

%)4 @Fmo&19*:

Std enthapy of

formation .f H o*+42

8%*44 B@Fmo9*:

Hazards

MS(S ICSC %$$4

HS pictograms

9!:

HS signa 7ord (anger

HS haard statements H*+$, H!%9!:

HS precautionary statementsP*4$, P!$)K!)%K!!4,P!%$

9!:

EU Inde= $%)8$%%8$$8"

EU cassification

C

;8phrases ;!

S8phrases .S%F*2, S*", S)

http://en.wikipedia.org/wiki/Acid_dissociation_constanthttp://en.wikipedia.org/wiki/Refractive_indexhttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Poisehttp://en.wikipedia.org/wiki/Poisehttp://en.wikipedia.org/wiki/Crystal_structurehttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/MSDShttp://www.inchem.org/documents/icsc/icsc/eics1008.htmhttp://en.wikipedia.org/wiki/GHS_hazard_pictogramshttp://en.wikipedia.org/wiki/Globally_Harmonized_System_of_Classification_and_Labelling_of_Chemicalshttp://en.wikipedia.org/wiki/GHS_hazard_statementhttp://en.wikipedia.org/wiki/GHS_precautionary_statementshttp://en.wikipedia.org/wiki/Dangerous_Substances_Directive_(67/548/EEC)http://en.wikipedia.org/wiki/List_of_R-phraseshttp://en.wikipedia.org/wiki/R34:_Causes_burnshttp://en.wikipedia.org/wiki/List_of_S-phraseshttp://en.wikipedia.org/wiki/(S1/2):_Keep_locked_up_and_out_of_the_reach_of_childrenhttp://en.wikipedia.org/wiki/S26:_In_case_of_contact_with_eyes,_rinse_immediately_with_plenty_of_water_and_seek_medical_advicehttp://en.wikipedia.org/wiki/S45:_In_case_of_accident_or_if_you_feel_unwell_seek_medical_advice_immediately_(show_the_label_where_possible)http://en.wikipedia.org/wiki/Acid_dissociation_constanthttp://en.wikipedia.org/wiki/Refractive_indexhttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Poisehttp://en.wikipedia.org/wiki/Crystal_structurehttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_molar_entropyhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/Standard_enthalpy_change_of_formationhttp://en.wikipedia.org/wiki/MSDShttp://www.inchem.org/documents/icsc/icsc/eics1008.htmhttp://en.wikipedia.org/wiki/GHS_hazard_pictogramshttp://en.wikipedia.org/wiki/Globally_Harmonized_System_of_Classification_and_Labelling_of_Chemicalshttp://en.wikipedia.org/wiki/GHS_hazard_statementhttp://en.wikipedia.org/wiki/GHS_precautionary_statementshttp://en.wikipedia.org/wiki/Dangerous_Substances_Directive_(67/548/EEC)http://en.wikipedia.org/wiki/List_of_R-phraseshttp://en.wikipedia.org/wiki/R34:_Causes_burnshttp://en.wikipedia.org/wiki/List_of_S-phraseshttp://en.wikipedia.org/wiki/(S1/2):_Keep_locked_up_and_out_of_the_reach_of_childrenhttp://en.wikipedia.org/wiki/S26:_In_case_of_contact_with_eyes,_rinse_immediately_with_plenty_of_water_and_seek_medical_advicehttp://en.wikipedia.org/wiki/S45:_In_case_of_accident_or_if_you_feel_unwell_seek_medical_advice_immediately_(show_the_label_where_possible)


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N/PA >$

$

!

$

/ash point Non8famma6e

D()$ .Detha dose2 %)!$ mgFBg .rat, ora2

Related compounds

;eatedphosphoruso=oacids Hypophosphorous acid

Phosphorous acid

Pyrophosphoric acid

riphosphoric acid

Perphosphoric acid

Permonophosphoric acid

E=cept 7here noted other7ise, data is gi> -/2, %$$ BPa2

Reactions

!nhydrous phosphoric acid, a "hite lo" melting solid, is obtained by

dehydration of &+' phosphoric acid by heating under a vacuum

Orthophosphoric acid is a very polar molecule :t is infinitely soluble in "ater

1he o#idation +state of phosphorus (8) in ortho. and other phosphoric acids is+E the o#idation state of all the o#ygen atoms (O) is 5 and all

the hydrogen atoms (H) is 7 1riprotic means that an orthophosphoric acid

molecule can dissociate up to three times, giving up an H each time, "hich

typically combines "ith a "ater molecule, H5O, as sho"n in these reactions>

H38O=(s) H5O(l) H3O

(aq) H58O=

(aq) K a7K 25+743

H58O=

(aq) H5O(l) H3O

(aq) H8O=5

(aq) K a5K %3774&

H8O=5(aq) H5O(l) H3O(aq) 8O=3(aq) K a3K =&47473

http://en.wikipedia.org/wiki/NFPA_704http://en.wikipedia.org/wiki/NFPA_704#Redhttp://en.wikipedia.org/wiki/NFPA_704#Bluehttp://en.wikipedia.org/wiki/NFPA_704#Yellowhttp://en.wikipedia.org/wiki/Flash_pointhttp://en.wikipedia.org/wiki/Median_lethal_dosehttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Oxoacidhttp://en.wikipedia.org/wiki/Hypophosphorous_acidhttp://en.wikipedia.org/wiki/Phosphorous_acidhttp://en.wikipedia.org/wiki/Pyrophosphoric_acidhttp://en.wikipedia.org/wiki/Triphosphoric_acidhttp://en.wikipedia.org/w/index.php?title=Perphosphoric_acid&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Permonophosphoric_acid&action=edit&redlink=1http://en.wikipedia.org/wiki/Standard_statehttp://en.wikipedia.org/wiki/Anhydroushttp://en.wikipedia.org/wiki/Chemical_polarityhttp://en.wikipedia.org/wiki/Moleculehttp://en.wikipedia.org/wiki/Oxidation_statehttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Water_(molecule)http://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/NFPA_704http://en.wikipedia.org/wiki/NFPA_704#Redhttp://en.wikipedia.org/wiki/NFPA_704#Bluehttp://en.wikipedia.org/wiki/NFPA_704#Yellowhttp://en.wikipedia.org/wiki/Flash_pointhttp://en.wikipedia.org/wiki/Median_lethal_dosehttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Oxoacidhttp://en.wikipedia.org/wiki/Hypophosphorous_acidhttp://en.wikipedia.org/wiki/Phosphorous_acidhttp://en.wikipedia.org/wiki/Pyrophosphoric_acidhttp://en.wikipedia.org/wiki/Triphosphoric_acidhttp://en.wikipedia.org/w/index.php?title=Perphosphoric_acid&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Permonophosphoric_acid&action=edit&redlink=1http://en.wikipedia.org/wiki/Standard_statehttp://en.wikipedia.org/wiki/Anhydroushttp://en.wikipedia.org/wiki/Chemical_polarityhttp://en.wikipedia.org/wiki/Moleculehttp://en.wikipedia.org/wiki/Oxidation_statehttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Water_(molecule)http://en.wikipedia.org/wiki/Chemical_reaction


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1he anion after the first dissociation, H58O=, is the dihydrogen

phosphate anion 1he anion after the second dissociation, H8O=5, is

thehydrogen phosphate anion 1he anion after the third dissociation, 8O=3, is

the phosphate or orthophosphate anion 9or each of the dissociation reactions

sho"n above, there is a separate acid dissociation constant, called K a7, K a5,

and K a3 given at 5+ M


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an e#tremely strong desiccant (and not by heating alone) :t

produces phosphoric anhydride(phosphorus pento#ide), "hich has an empirical

formula 85O+, although an actual molecule has a chemical formula of 8=O74

8hosphoric anhydride is a solid, "hich is very strongly moisture.absorbing and

is used as a desiccant

'(ueous solution

9or a given total acid concentration P!Q K PH38O=Q PH58O=Q PH8O=

5Q

P8O=3Q (P!Q is the total number of moles of pure H 38O= "hich have been used

to prepare 7 liter of solution), the composition of an aqueous solution of

phosphoric acid can be calculated using the equilibrium equations associated

"ith the three reactions described above together "ith the PHQ POHQ K

747= relation and the electrical neutrality equation 8ossible concentrations of

polyphosphoric molecules and ions is neglected 1he system may be reduced to

a fifth degree equation for PHQ "hich can be solved numerically, yielding>

)'*+mol%

-

pH)H.PO/*)'*

+0-

)H1PO/2*)'*

+0-

)HPO/12*)'*

+0-

)PO/.2*)'*

+0-

% %#$4 345 4#*+ "#*$T%$'" %#"$T%$'%>

%$'% %#"* 564 *!#+ "#*$T%$') )#))T%$'%"

%$'* *#*) /.4 763 "#*$T%$' *#!!T%$'%

%$'! !#$) %$#" 83. "#*$T%$'! %#4T%$'%*

%$' #$% %#!$ 386 "#%+T%$'* %#!T%$'%$

%$') )#$$ $#%!! 33. $#"%* %#!$T%$'4

http://en.wikipedia.org/wiki/Desiccanthttp://en.wikipedia.org/wiki/Phosphorus_pentoxidehttp://en.wikipedia.org/wiki/Desiccanthttp://en.wikipedia.org/wiki/Desiccanthttp://en.wikipedia.org/wiki/Phosphorus_pentoxidehttp://en.wikipedia.org/wiki/Desiccant


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%$'" )#+> %#!T%$'* 3/7 )#)$ %#%%T%$'"

%$'> "#> %#4$T%$'! 5/7 *)#) !#$*T%$')

%$'%$ >#$$ 4#*T%$' 645 .8. 4#%4T%$')

9or strong acid concentrations, the solution is mainly composed of H38O= 9or

P!Q K 745, the pH is close to p K a7, giving an equimolar mi#ture of H38O= and

H58O= 9or P!Q belo" 743, the solution is mainly composed of H58O=

"ith

PH8O=5Q becoming non negligible for very dilute solutions P8O=

3Q is al"ays

negligible /ince this analysis does not take into account ion activity

coefficients, the pH and molarity of a real phosphoric acid solution may deviatesubstantially from the above values

9ood additi:e

9ood.grade phosphoric acid (additive L33&P77Q) is used to acidify foods and

beverages such as various colas :t provides a tangy or sour taste

Rarious salts of phosphoric acid, such as monocalcium phosphate, are used as

leavening agents

Niche uses8hosphoric acid and its derivatives are pervasive and find many niche

applicationsRust remo:al

8hosphoric acid may be used to remove rust by direct application to rusted iron,

steel tools, or other surfaces 1he phosphoric acid changes the reddish.

bro"n iron(:::) o#ide, 9e5O3 (rust) to ferric phosphate, 9e8O= !n empirical

formula for this reaction is>5 H38O= 9e5O3 I 5 9e8O= 3 H5O

Fiquid phosphoric acid may be used for dipping, but phosphoric acid for rust

removal is more often formulated as a gel !s a thick gel, it may be applied to

sloping, vertical, or even overhead surfaces Bifferent phosphoric acid gel

formulations are sold as Srust removersS or Srust killersS 6ultiple applications

of phosphoric acid may be required to remove all rust ;ust may also be

removed via phosphate conversion coating 1his process can leave a black

http://en.wikipedia.org/wiki/E_numberhttp://en.wikipedia.org/wiki/E_numberhttp://en.wikipedia.org/wiki/Colahttp://en.wikipedia.org/wiki/Salt_(chemistry)http://en.wikipedia.org/wiki/Monocalcium_phosphatehttp://en.wikipedia.org/wiki/Leavening_agenthttp://en.wikipedia.org/wiki/Iron(III)_oxidehttp://en.wikipedia.org/wiki/Rusthttp://en.wikipedia.org/wiki/Iron(III)_phosphatehttp://en.wikipedia.org/wiki/Gelhttp://en.wikipedia.org/wiki/Phosphate_conversion_coatinghttp://en.wikipedia.org/wiki/E_numberhttp://en.wikipedia.org/wiki/Colahttp://en.wikipedia.org/wiki/Salt_(chemistry)http://en.wikipedia.org/wiki/Monocalcium_phosphatehttp://en.wikipedia.org/wiki/Leavening_agenthttp://en.wikipedia.org/wiki/Iron(III)_oxidehttp://en.wikipedia.org/wiki/Rusthttp://en.wikipedia.org/wiki/Iron(III)_phosphatehttp://en.wikipedia.org/wiki/Gelhttp://en.wikipedia.org/wiki/Phosphate_conversion_coating


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phosphate coating that provides moderate corrosion resistance (such protection

is also provided by the superficially

similar 8arkeri0ing and blued electrochemical conversion coating processes)

In medicine8hosphoric acid is used in dentistry and orthodontics as an etching solution, to

clean and roughen the surfaces of teeth "here dental appliances or fillings "ill

be placed 8hosphoric acid is also an ingredient in over.the.counter anti.nausea

medications that also contain high levels of sugar (glucose and fructose) 1his

acid is also used in many teeth "hiteners to eliminate plaque that may be on the

teeth before application

/ther applications!mong other applications, phosphoric acid is used>

7Q !s a solution for anodi0ing

5Q !s an e#ternal standard for phosphorus.37 Nuclear magnetic

resonance (N6;)

3Q !s a buffer agent in biology and chemistryE 9or e#ample, a buffer

for high.performance liquid chromatography

=Q !s a chemical o#idi0ing agent for activated carbon production, as used in

the Gent"orth 8rocessP75Q

+Q !s the electrolyte in phosphoric acid fuel cells

%Q Gith distilled "ater (53 drops per gallon) as an electrolyte in

o#yhydrogen generators

2Q !s a catalyst in the hydration of alkenes to produce alcohols,

predominantly ethanol

&Q !s an electrolyte in copper electropolishing for burr removal and circuit

board planari0ation*Q !s a flu# by hobbyists (such as model railroaders) as an aid to soldering

74Q :n compound semiconductor processing, phosphoric acid is a

common "et etching agent> for e#ample, in combination "ith hydrogen

pero#ide and "ater it is used to etch :n@a!s selective to :n8P73Q

77Q Heated in microfabrication to etch silicon nitride (/i3 N=) :t is

highly selective in etching /i3 N= instead of /iO5, silicon dio#ideP7=Q

75Q !s a cleaner by construction trades to remove mineral deposits,

cementitious smears, and hard "ater stains

http://en.wikipedia.org/wiki/Parkerizehttp://en.wikipedia.org/wiki/Bluing_(steel)http://en.wikipedia.org/wiki/Conversion_coatinghttp://en.wikipedia.org/wiki/Dentistryhttp://en.wikipedia.org/wiki/Orthodonticshttp://en.wikipedia.org/wiki/Etchinghttp://en.wikipedia.org/wiki/Sugarhttp://en.wikipedia.org/wiki/Glucosehttp://en.wikipedia.org/wiki/Fructosehttp://en.wikipedia.org/wiki/Nuclear_magnetic_resonancehttp://en.wikipedia.org/wiki/Nuclear_magnetic_resonancehttp://en.wikipedia.org/wiki/High-performance_liquid_chromatographyhttp://en.wikipedia.org/wiki/Activated_carbonhttp://en.wikipedia.org/wiki/Electrolytehttp://en.wikipedia.org/wiki/Phosphoric_acid_fuel_cellhttp://en.wikipedia.org/wiki/Electrolytehttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Electropolishinghttp://en.wikipedia.org/wiki/Flux_(metallurgy)http://en.wikipedia.org/wiki/Solderinghttp://en.wikipedia.org/wiki/Compound_semiconductorhttp://en.wikipedia.org/wiki/Indium_gallium_arsenidehttp://en.wikipedia.org/wiki/Indium_phosphidehttp://en.wikipedia.org/wiki/Microfabricationhttp://en.wikipedia.org/wiki/Silicon_nitridehttp://en.wikipedia.org/wiki/Silicon_dioxidehttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Parkerizehttp://en.wikipedia.org/wiki/Bluing_(steel)http://en.wikipedia.org/wiki/Conversion_coatinghttp://en.wikipedia.org/wiki/Dentistryhttp://en.wikipedia.org/wiki/Orthodonticshttp://en.wikipedia.org/wiki/Etchinghttp://en.wikipedia.org/wiki/Sugarhttp://en.wikipedia.org/wiki/Glucosehttp://en.wikipedia.org/wiki/Fructosehttp://en.wikipedia.org/wiki/Nuclear_magnetic_resonancehttp://en.wikipedia.org/wiki/Nuclear_magnetic_resonancehttp://en.wikipedia.org/wiki/High-performance_liquid_chromatographyhttp://en.wikipedia.org/wiki/Activated_carbonhttp://en.wikipedia.org/wiki/Electrolytehttp://en.wikipedia.org/wiki/Phosphoric_acid_fuel_cellhttp://en.wikipedia.org/wiki/Electrolytehttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Electropolishinghttp://en.wikipedia.org/wiki/Flux_(metallurgy)http://en.wikipedia.org/wiki/Solderinghttp://en.wikipedia.org/wiki/Compound_semiconductorhttp://en.wikipedia.org/wiki/Indium_gallium_arsenidehttp://en.wikipedia.org/wiki/Indium_phosphidehttp://en.wikipedia.org/wiki/Microfabricationhttp://en.wikipedia.org/wiki/Silicon_nitridehttp://en.wikipedia.org/wiki/Silicon_dioxidehttp://en.wikipedia.org/wiki/Construction


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73Q !s a chelant in some household cleaners aimed at similar cleaning

tasks

7=Q :n hydroponics pH solutions to lo"er the pH of nutrient solutions

Ghile other types of acids can be used, phosphorus is a nutrient used by plants, especially during flo"ering, making phosphoric acid particularly

desirable

7+Q !s a pH adjuster in cosmetics and skin.care productsP7+Q

7%Q !s a dispersing agent in detergents and leather treatment

72Q !s an additive to stabili0e acidic aqueous solutions "ithin a "anted

and specified pH range

8hosphoric acid, used in many soft drinks (primarily cola), has been linked in

epidemiological studies to (7) chronic kidney disease and (5) lo"er bone

density

! study performed by the Lpidemiology -ranch of the / National :nstitute of

Lnvironmental Health /ciences, concludes that drinking 5 or more colas per day

"as associated "ith doubling the risk of chronic kidney disease

Applicati

on

4emand(%&&+) in

thousands

of tons

Main phosphate deri!ati!es

/oaps and

detergents7&3% /188

9oodindustry

34* /188 (Na+83O74), /H68, 1/8, /!88, /!l8 (Na!, 6


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Other

applicatio

ns

5&2

/188 (Na383O*), 1


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8hosphoric acid is produced industrially by t"o general routes the thermal

process and the "et process, "hich includes t"o sub.methods 1he "et process

dominates in the commercial sector 1he more e#pensive thermal process

produces a purer product that is used for applications in the food industry

5et

Get process phosphoric acid is prepared by adding sulfuric acid to tricalcium

phosphate rock, typically found in nature as apatite 1he reaction is>


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phosphoric acid 1his route produces a very pure phosphoric acid, since most

impurities present in the rock have been removed "hen e#tracting phosphorus

from the rock in a furnace 1he end result is food.grade, thermal phosphoric

acidE ho"ever, for critical applications, additional processing to remove arsenic

compounds may be needed

Llemental phosphorus is produced by an electric furnace !t a high temperature,

a mi#ture of phosphate ore, silica and carbonaceous material (coke, coal etc)

produces calcium silicate, phosphorus gas and carbon mono#ide 1he 8 and


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calcium sulfate (gypsum) plus other insoluble impurities Gater is added and

the gypsum is removed by filtration along "ith other insoluble materials (eg

silica) 9luoride, as H5/i9%, is removed at a further stage by evaporation!lthough the reaction takes place in stages involving calcium

dihydrogenphosphate, the overall reaction can be represented as>

Ho"ever, there are side reactionsE for e#ample "ith calcium fluoride and

calcium carbonate present in the rock>

9luorosilicilic acid is an important by.product from this and from the

manufacture of hydrogen fluoride :t can be neutralised "ith sodium

hydro#ide to form sodium he#afluorosilicate 1he acid is also used to

make aluminium fluoride, used in turn in the manufacture of aluminium

1he crystal structure of the calcium sulfate formed depends on the conditions

of the reaction !t 3=4.3+4 $, the principal product is dihydrate,


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further purified using solvents to e#tract it from heavy metals and

defluorinated (by evaporation) to produce a product of food grade quality

(b) Thermal process

1he ra" materials for this process are phosphorus and air>

:nitially, phosphorus is sprayed into the furnace and is burnt in air at about

7&44.3444 $

6ost processes use undried air and many involve the addition of steam to the

phosphorus burner to produce and maintain a film of condensed

polyphosphoric acids "hich protect the stainless steel burner to"er

(e#ternally "ater cooled) 1he products from the burner to"er pass directly

into a hydration to"er "here the gaseous phosphorus o#ide is absorbed in

recycled phosphoric acid>

!lternatively, the phosphorus may be burnt in dried air 1he phosphorus

pento#ide is condensed as a "hite po"der and separately hydrated to

phosphoric acid

1his method allo"s heat to be recovered and reused

-urning and direct hydration, as previously described, creates highly

corrosive conditions 1he equipment is constructed from stainless steel or is

carbon brick.lined 1o reduce corrosion, the "alls of the burner and hydrator

to"ers are cooled, but the reactor products emerge at a temperature too lo"

for useful heat recovery

1he product acid has a concentration of ca &+'

1etraphosphoric acid, one of a family of polyphosphoric acids "hich can be

selectively produced, is made either by boiling off "ater at high temperatures

in a carbon vessel, or by adding solid phosphorus pento#ide to almost boiling


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phosphoric acid 1he first method usually gives the purer product, due to the

high arsenic content of phosphorus pento#ide

0hosphates

1he salts of phosphoric acid, the phosphates, are the compounds that are

"idely used in agriculture, industry and in the home

(a) Ammonium phosphates

6onoammonium dihydrogenphosphate and diammonium hydrogenphosphate

are much used as fertili0ers and are made by mi#ing the correct proportions of

phosphoric acid "ith anhydrous ammonia in a rotating drum

1he choice of "hich ammonium phosphate to use depends on the proportion

of nitrogen and phosphorus needed for the crop

(b) Calcium phosphates

1he calcium phosphates are used e#tensively as fertili0ers

1his is kno"n as triple superphosphate 1he higher level of phosphate is

achieved because the product is no longer diluted "ith calcium sulfate

(c) Sodium phosphates

/odium phosphates are produced by reaction of phosphoric acid and a

concentrated solution of sodium hydro#ide in the appropriate (stoichiometric)

proportions 1he product crystalli0es out

http://www.essentialchemicalindustry.org/materials-and-applications/fertilizers.htmlhttp://www.essentialchemicalindustry.org/materials-and-applications/fertilizers.htmlhttp://www.essentialchemicalindustry.org/materials-and-applications/fertilizers.htmlhttp://www.essentialchemicalindustry.org/materials-and-applications/fertilizers.html


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