Question

What happens when gypsum is heated to 393 K ?

Answer 1

All  the alkali metals when heated with oxygen form different types of oxides.Higher energy levels and the absorption of photons occurs in the red region,it is obtained when gypsum is heated at 393k.

Answer 2

When Gypsum is heated to 393K, it gets converted into "Plaster of Paris".

Explanation:

The chemical name of Gypsum is “calcium sulphate dehydrate". When Gypsum is warmed up to 393 K, it loses all its water and crystallizes to give anhydrous calcium sulphate or calcium sulphate hemihydrate.

This is known as "dead burnt plaster" or "Plaster of Paris".

The chemical equation for the formation of anhydrous calcium sulphate is given below:

$\mathrm{CaSO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O} \stackrel{393 \mathrm{K}}{\longrightarrow} \mathrm{CaSO}_{4 \cdot} \frac{1}{2} \mathrm{H}_{2} \mathrm{O}+\frac{3}{2} \mathrm{H}_{2} \mathrm{O}$