Sodium sulfite
 Sample of crystalline sodium sulfite
| |
| Names | |
|---|---|
| IUPAC name
Sodium sulfite
| |
| Other names
Disodium sulfite
E221 Hypo clear (photography) Sodium sulphite Sulfurous acid, sodium salt | |
| Properties | |
| Na2SO3 | |
| Molar mass | 126.043 g/mol |
| Appearance | White solid |
| Odor | Odorless |
| Density | 2.633 g/cm3 (anhydrous) 1.561 g/cm3 (heptahydrate) |
| Melting point | 33.4 °C (92.1 °F; 306.5 K) (heptahydrate, decomposition) 500 °C (932 °F; 773.15 K) (anhydrous, decomposes) |
| Boiling point | Decomposes |
| 27.0 g/100 mL water (20 °C) | |
| Solubility | Soluble in glycerol Insoluble in ammonia, chlorine, ethanol, isopropanol |
| Acidity (pKa) | ~9 (heptahydrate) |
| Hazards | |
| Safety data sheet | FisherScientific |
| Flash point | Non-flammable |
| Related compounds | |
| Related compounds
|
Potassium sulfite |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Sodium sulfite is a chemical compound with the formula Na2SO3, used as a reducing agent.
Contents
Properties
Chemical
Sodium sulfite releases sulfur dioxide if a strong acid, such as hydrochloric acid, is added.
- Na2SO3 + 2 HCl → 2 NaCl + SO2 + H2O
Sodium sulfite will slowly oxidize in air to sodium sulfate.
Physical
Sodium sulfite is an odorless white crystalline solid, soluble in water and glycerol.
Availability
Sodium sulfite can be purchased from various food retailers as antioxidant for foods.
It can also be purchased from chemical suppliers.
Preparation
Can be made by bubbling sulfur dioxide in a solution of sodium hydroxide, while maintaining the pH>7.
Projects
- Reducing agent
- Etard reaction
- Neutralize bleach
- Bucherer reaction
- Corrosion inhibitor
Handling
Safety
Sodium sulfite is irritant and should be handled with care.
Storage
Sodium sulfite should be kept in closed bottles, away from air.
Disposal
Neutralization is not always necessary, but it can be destroyed with bleach.
