Sodium Sulfite
Disodium Sulfite
- CAS
- 7757-83-7
- EC
- 231-821-4
- Food Code
- E221
- Sectors
- Food & Nutrition, Water & Wastewater Treatment, Textiles, Leather & Paper
Sodium Sulfite (CAS 7757-83-7) is an inorganic sodium salt from the salts and minerals group that appears as a white to slightly yellow crystalline solid, acts as a reducing agent, and is used as a food preservative, an oxygen scavenger in water treatment, and a bleaching agent in paper. Density 2.63 g/cm³, decomposes above 100°C; highly soluble in water (up to 220 g/L at 20°C), slightly sulfurous odor. Acts as a reducing agent; produced by reacting sulfur dioxide with sodium carbonate.
Typical Properties
| Molecular formula | H2O3S.2Na |
|---|---|
| Molecular weight | 126.04 g/mol |
| Appearance | Sodium sulfite is a white crystalline solid |
| Form | Solid |
| Color | White to slightly yellow |
| Odor | Odorless |
| Melting point | 500 °C |
| Density | 2.63 g/cm³ |
| Water solubility | 23 g/100 mL (20 °C) |
| pH | 9.0-10.5 (25°C, 1M in H2O) |
| GHS signal word | Danger · Corrosive, Irritant / harmful |
| HS code | 28321000 |
| Grades available | Food Grade, Technical Grade |
Typical literature values for identification; lot-specific results are stated on the certificate of analysis (COA) and the safety data sheet (SDS) that accompany every delivery.
Sodium Sulfite
Applications
Used as preservative in food, antioxidant in pharmaceuticals, bleaching agent in paper, water treatment for oxygen scavenging, and photography.
Safety & Risks
Moderately toxic; irritates skin, eyes, respiratory tract; releases SO2 with acids. Avoid oxidizers; use PPE, ventilation.
Packaging
In 25kg bags or drums; moisten spills before sweeping; rinse containers for recycling.