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| IUPAC name
| Other names
Disulfuric acid disodium salt
|Molar mass||222.12 g/mol|
|Appearance||White crystalline solid|
|Melting point||400.9 °C (753.6 °F; 674.0 K)|
|Boiling point||460 °C (860 °F; 733 K) (decomposition)|
Std enthalpy of
|Safety data sheet||None|
| Sodium bisulfate|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Sodium pyrosulfate (also known as disodium disulfate) is a sodium salt of disulfuric acid, with the formula Na2S2O7.
- Na2S2O7 → Na2SO4 + SO3
This reaction is a convenient way of obtaining sulfur trioxide, as it does not require complex installation and the pyrosulfate precursor, sodium bisulfate, is readily available.
Sodium pyrosulfate hydrolyzes in water to sulfuric acid.
Sodium disulfate is a white salt, soluble in water.
Sodium pyrosulfate is rarely available from suppliers. Sigmaaldrich used to sell sodium disulfate fused with sodium bisulfate.
Sodium pyrosulfate can be easily made by heating sodium bisulfate at temperatures between 200-400 °C:
- 2 NaHSO4 → Na2S2O7 + H2O
However, other authors indicate different temperature decomposition ranges.
- Make sulfur trioxide
- Make ammonium pyrosulfate
Sodium pyrosulfate rapidly hydrolyzes in contact with water, releasing sulfuric acid, which is corrosive.
In closed bottles, away from any moisture.
Add it in large amounts of water to hydrolyze it, then carefully neutralize the acid with a base.