3 (anhydrous); MgSO
|Molar mass||104.368200 g/mol (anhydrous)
212.4599 g/mol (hexahydrate)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Magnesium sulfite is the magnesium salt of sulfurous acid with the formula MgSO
3. Its most common hydrated form has 6 water molecules making it a hexahydrate, MgSO
2O. When heated above 40 °C (104 °F), it is dehydrated to magnesium sulfite trihydrate, or MgSO
2O. The anhydrous form is hygroscopic, meaning that it readily absorbs water from the air.
- Nývlt, J., "Solubilities of Magnesium Sulfite," Journal of Thermal Analysis and Calorimetry, Volume 66, Number 2 / November, 2001