Question

What happens when gypsum heated with $373\mathrm{K}$?

Answer 1

Heating of Gypsum

• When gypsum $\left({\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}\right)$ is heated to $373\mathrm{K}$, it forms calcium sulfate hemihydrate.
• The calcium sulfate hemihydrate is also known as the “Plaster of Paris.”.

Balanced chemical reaction

• The reaction is as follows:

$\underset{\left(\mathrm{Gypsum}\right)}{{\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{s}\right)}\stackrel{373\mathrm{K}}{\to }\underset{\left(\mathrm{Plaster}\mathrm{of}\mathrm{Paris}\right)}{{\mathrm{CaSO}}_4.\frac{1}{2}{\mathrm{H}}_2\mathrm{O}\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Water}\right)}{\frac{3}{2}{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$