| IUPAC name
| Other names
Sulfurous acid, diammonium salt
| (NH4)2SO3 (anhydrous)|
|Molar mass||116.14 g/mol|
|Appearance||Whitish hygroscopic solid|
|Density||1.41 g/cm3 (at 25 °C)|
|Melting point||65 °C (149 °F; 338 K) (decomposes)|
| 32.4g/100ml (at 0 °C)|
35.0 g/100 ml (at 20 °C)
60.4g/100ml (at 100 °C)
|Solubility|| Reacts with acids|
Insoluble in acetone, ethanol, toluene
|Safety data sheet||Sigma Aldrich (monohydrate)|
| Ammonium bisulfite|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Ammonium sulfite is a colorless hygroscopic salt of ammonia with the formula (NH4)2SO3.
Ammonium sulfite is slowly oxidized to ammonium sulfate in open air.
- (NH4)2SO3 + ½ O2 → (NH4)2SO4
Addition of a strong acid will release sulfur dioxide:
- (NH4)2SO3 + 2 HCl → 2 NH4Cl + SO2 + H2O
Ammonium sulfite is a colorless hygroscopic solid, soluble in water but insoluble in organic solvents.
Some hair straightening and waving products contain ammonium sulfite. It can also be found on Amazon.
Lastly it can also be bought from suppliers.
Like most sulfites, ammonium sulfite can be made by bubbling sulfur dioxide through a cold solution of excess ammonia.
- Reducing agent
- Make ammonium sulfate
Ammonium sulfite has low toxicity, though it can be irritant on contact.
In sealed bottles, away from air or acids.
Leaving it in open air will convert it in ammonium sulfate. Bleach or hydrogen peroxide can also be used to accelerate the reaction. The resulting ammonium sulfate can be poured down the drain, thrown in the trash or dumped in ground.