Soda Ash Light
- Sodium Carbonate Decahydrate (Natron), Na2co3·10h2o, Which Readily Effloresces to Form the Monohydrate.
- Sodium Carbonate Heptahydrate (Not Known in Mineral Form), Na2co3â·7h2o.
- Sodium Carbonate Monohydrate (Thermonatrite), Na2co3.h2o. Also Known as Crystal Carbonate.
- Anhydrous Sodium Carbonate, Also Known as Calcined Soda, is Formed by Heating the Hydrates. It is Also Formed When Sodium Hydrogen Carbonate is Heated (Calcined) E.g. In the Final Step of the Solvay Process.
The Decahydrate is Formed From Water Solutions Crystallizing in the Temperature Range -2.1 to +32.0 C, the Heptahydrate in the Narrow Range 32.0 to 35.4 C and Above This Temperature the Monohydrate Forms. in Dry Air the Decahydrate and Heptahydrate Lose Water to Give the Monohydrate. Other Hydrates Have Been Reported, E.g. With 2.5 Units of Water Per Sodium Carbonate Unit ("Pentahemihydrate")