Dehydration of sodium carbonate monohydrate

The kinetics and mechanism of the thermal decomposition of solid sodium carbonate monohydrate have been studied between 336 and 400 K at water-vapour pressures up to 20 kN m–2. The dehydration follows Avrami–Erofeyev kinetics (n= 2) with a limiting activation energy of 71.5 kJ mol–1 and a frequency factor of 2.2 × 107 S–1. The reaction rate is reduced by increasing the water-vapour pressure and this has been accounted for in terms of competition from the rehydration reaction.