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Chemical formula H₄P₂O₇ SMILES OP(=O)(O)OP(=O)(O)O Molecular mass 177.98 g/mol CAS number 2466-09-3

Density ? g/cm³ Melting point 61 °C Boiling point ? °C Dissociation
constants Ka₁ = 3 × 10^-2
Ka₂ = 4.4 × 10^-3
Ka₃ = 2.5 × 10^-7
Ka₄ = 5.6 × 10^-10

Pyrophosphoric acid, also known under the name diphosphoric acid, is a syrupy liquid or a needle-like crystaline solid. Pyrophosphoric acid is colorless, odorless, hygroscopic and is soluble in water, diethyl ether, and ethyl alcohol. It is the anhydride of phosphoric acid and is produced from phosphoric acid by dehydration. Pyrophosphoric acid slowly hydrolyzes in the presence of water into phosphoric acid.

2H₃PO₄ ⇌ H₄P₂O₇ + H₂O

Pyrophosphoric acid is a medium strong inorganic acid. The anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates.

See also

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• Sodium pyrophosphate
• Calcium pyrophosphate dihydrate deposition disease
• Dimethylallyl pyrophosphate
• ATP

External links

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• Dissociation constants
• Pyrophosphoric acid at PubChem

Phosphates | Acids

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