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Phosphorous Acid Chemical Formula H3PO3 , Phosphorous Acid Industrial Grade 

Phosphorous Acid Chemical Formula H3PO3 , Phosphorous Acid Industrial Grade 

  • Phosphorous Acid Chemical Formula H3PO3 , Phosphorous Acid Industrial Grade 
  • Phosphorous Acid Chemical Formula H3PO3 , Phosphorous Acid Industrial Grade 
Phosphorous Acid Chemical Formula H3PO3 , Phosphorous Acid Industrial Grade 
Product Details:
Place of Origin: Hunan
Brand Name: Kemsky/SGS
Certification: ISO 9001
Model Number: Phosphorus trihydroxiden H3PO3
Payment & Shipping Terms:
Minimum Order Quantity: 1 metric ton
Price: usd 1250 per ton
Packaging Details: 25 kgs bag,1000 kgs big bag
Delivery Time: 5-8 days
Payment Terms: T/T , L/C
Supply Ability: 3000 tons per month
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Detailed Product Description
Name: Phosphorous Acid H3PO3 Other Name: Orthophosphorous Acid H3PO3
Color: Colorless Situation: Crystalline Solid Granule
Mocular: H3PO3 Grade: Industry Grade
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Phosphorous acid H3PO3 CAS No: 13598-36-2

Phosphorous acid H3PO3

Phosphorous acid CAS No: 13598-36-2

Product Description

Phosphorous acid is a colorless crystal. It can be slowly oxidized to phosphoric acid in the air. When heated to 180 °C, it can be decomposed into phosphoric acid and phosphine (highly toxic). As a dibasic acid, it has slightly ber acidity than phosphoric acid. Phosphorous acid has b reducibility and can easily reduce Ag+ to metal silver. It can also reduce sulfuric acid to sulfur dioxide. It is corrosive and has b hygroscopicity.

Product Parameters

Apperance White Crystal Main content 99%min
Chloride 0.01%max Iron 0.008%max
Phosphate 0.01%max Sulfate 0.006%max
Heavy metal 0.001%max Water-solubility Excellent


Phosphorous acid


Reductions of metal ions


Both phosphorous acid and its deprotonated forms are good reducing agents, although not necessarily quick to react. They are oxidized to phosphoric acid or its salts. It reduces solutions of noble metal cations to the metals. When phosphorous acid is treated with a cold solution of mercuric chloride, a white precipitate of mercurous chloride forms:

H3PO3 + 2 HgCl2 + H2O → Hg2Cl2 + H3PO4 + 2 HCl

Mercurous chloride is reduced further by phosphorous acid to mercury on heating or on standing:

H3PO3 + Hg2Cl2 + H2O → 2 Hg + H3PO4 + 2 HCl


Acid–base properties

Phosphorous acid is a strong acid with a pKa in the range 1.26–1.3.[4][5]

HP(O)(OH)2 → HP(O)2(OH) + H+ pKa = 1.3

It is adiprotic acid , the hydrogenphosphite ion, HP(O)2(OH) is a moderately strong acid:

HP(O)2(OH) → HPO32− + H+ pKa = 6.7

The conjugate base HP(O)2(OH) is called hydrogen phosphite, and the second conjugate base, HPO2−
3, is the phosphite ion.[6] (Note that the IUPAC recommendations are hydrogen phosphonate and phosphonate respectively).

The hydrogen bonded directly to the phosphorus atom is not readily ionizable. Chemistry examinations often test students' appreciation of the fact that not all three hydrogen atoms are acidic under aqueous conditions, in contrast with H3PO4.

Technical data


Items Testing Result
Appearance White Powder
Purity (%) 99.0 %min
Chloride (%) 0.01%max
SO42(%) 0.01%max
PO42(%) 0.2%max
Iron (as Fe, ppm) 0.001%max


The most important use of phosphorous acid (phosphonic acid) is the production of basic lead phosphite, which is a stabilizer in PVC and related chlorinated polymers.[3]
Phosphites have shown effectiveness in controlling a variety of plant diseases, in particular, treatment using either trunk injection or foliar containing phosphorous acid salts is indicated in response to infections by phytophthora and pythium-type plant pathogens (both within class oomycetes, known as water molds), such as dieback/root rot and downy mildew.[10] Anti-microbial products containing salts of phosphorous acid are marketed in Australia as 'Yates Anti-Rot'; and in the United States of America, for example, aluminum salts of the monoethyl ester of phosphorous acid (known generically as 'Fosetyl-Al') are sold under the trade name 'Aliette'. Phosphorous acid and its salts, unlike phosphoric acid, are somewhat toxic and should be handled carefully.

Organic derivatives

The IUPAC (mostly organic) name is phosphonic acid. This nomenclature is commonly reserved for substituted derivatives, that is, organic group bonded to phosphorus, not simply an ester. For example, (CH3)PO(OH)2 is "methylphosphonic acid", which may of course form "methylphosphonate" esters.
Phosphorous acid H3PO3 CAS No: 13598-36-2


Product properties


Appearance: white crystal

Density: 1.65

Melting point:73

Boiling point: 200

UN No:2834

Haradous class: 8


Product Name


As a ligand

Upon treatment with metals of d6 configuration, phosphorous acid is known to coordinate as the otherwise rare P(OH)3 tautomer. Examples include Mo(CO)5(P(OH)3) and [Ru(NH3)4(H2O)(P(OH)3)]2+.[8][9]


On heating at 200 °C, phosphorous acid disproportionates to phosphoric acid and phosphine:[7]
4 H3PO3 → 3 H3PO4 + PH3
This reaction is used for laboratory-scale preparations of PH3.

HPO(OH)2 is the product of the hydrolysis of its acid anhydride:
P4O6 + 6 H2O → 4 HPO(OH)2
(An analogous relationship connects H3PO4 and P4O10).
On an industrial scale, the acid is prepared by hydrolysis of phosphorus trichloride with water or steam:[3]
PCl3 + 3 H2O → HPO(OH)2 + 3 HCl
Potassium phosphite is also a convenient precursor to phosphorous acid:
K2HPO3 + 2 HCl → 2 KCl + H3PO3
In practice aqueous potassium phosphite is treated with excess hydrochloric acid. By concentrating the solution and precipitations with alcohols, the pure acid can be separated from the salt.
Nomenclature and tautomerism

H3PO3 is more clearly described with the structural formula HPO(OH)2. In the solid state, HP(O)(OH)2 is tetrahedral with one shorter P=O bond of 148 pm and two longer P–O(H) bonds of 154 pm. This species exists in equilibrium with an extremely minor tautomer P(OH)3. IUPAC recommends that the latter be called phosphorous acid, whereas the dihydroxy form is called phosphonic acid.[2] Only the reduced phosphorus compounds are spelled with an "ous" ending.
Other important oxyacids of phosphorus are phosphoric acid (H3PO4) and hypophosphorous acid (H3PO2). The reduced phosphorus acids are subject to similar tautomerism involving shifts of H between O and P.
Phosphorous acid is the compound described by the formula H3PO3. This acid is diprotic (readily ionizes two protons), not triprotic as might be suggested by this formula. Phosphorous acid is an intermediate in the preparation of other phosphorus compounds.Product Applications

Usage: Widely used in the production of phosphite materials, as the raw material in the production of plastic stabilizer in plastic industry, as reducing agent in chemical reaction, it can be used in the synthesis of fiber and pesticide industry, etc


Phosphorous Acid Chemical Formula H3PO3 , Phosphorous Acid Industrial Grade  0




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