Sodium hydrogen sulfite
E222, sodium bisulphite
3D model (JSmol)
|E number||E222 (preservatives)|
CompTox Dashboard (EPA)
|Molar mass||104.061 g/mol|
|Odor||Slight sulfurous odor|
|Melting point||150 °C (302 °F; 423 K)|
|Boiling point||315 °C (599 °F; 588 K)|
|42 g/100 mL|
Refractive index (nD)
|R-phrases (outdated)||R22 R31|
|S-phrases (outdated)||(S2), S25, S46|
|NFPA 704 (fire diamond)|
|NIOSH (US health exposure limits):|
|TWA 5 mg/m3|
IDLH (Immediate danger)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Sodium bisulfite (or sodium bisulphite, sodium hydrogen sulfite) is a chemical mixture with the approximate chemical formula NaHSO3. Sodium bisulfite in fact is not a real compound, but a mixture of salts that dissolve in water to give solutions composed of sodium and bisulfite ions. It is a white solid with an odour of sulfur dioxide. Regardless of its ill-defined nature, "sodium bisulfite" is a food additive with E number E222.
- SO2 + NaOH → NaHSO3
- SO2 + NaHCO3 → NaHSO3 + CO2
Reactivity and uses
Sodium bisulfite is a common industrial reducing agent, as it readily reacts with dissolved oxygen:
- 2 NaHSO3 + O2 → 2 NaHSO4
It is usually added to large piping systems to prevent oxidative corrosion. In biochemical engineering applications, it is helpful to maintain anaerobic conditions within a reactor.
It is used for preserving food and beverages.
- NIOSH Pocket Guide to Chemical Hazards. "#0561". National Institute for Occupational Safety and Health (NIOSH).
- Tudela, David; Jenkins, H. Donald B. (2003). "New Methods to Estimate Lattice Energies: Application to the Relative Stabilities of Bisulfite (HSO3−) and Metabisulfite (S2O52-) Salts". Journal of Chemical Education. 80 (12): 1482. Bibcode:2003JChEd..80.1482T. doi:10.1021/ed080p1482.
- Johnstone, H. F. (1946). "Sulfites and Pyrosulfites of the Alkali Metals". Inorganic Syntheses. Inorganic Syntheses. 2. pp. 162–167. doi:10.1002/9780470132333.ch49. ISBN 9780470132333.