Question

Identify the compound of calcium that is used for plastering fractured bones. With the help of a chemical equation show, how is it prepared, and whether special precautions should be taken during the preparation of this compound?

Answer 1

Name of the compound:
Plaster of Paris is the compound used for plastering fractured bones. It is also known as Calcium Sulphate Hemihydrate.

Preparation of Plaster of Paris:

It is prepared by heating Gypsum (${\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}$) at 373K. It loses its water molecules due to heating and turns into Calcium sulfate hemihydrate (${\mathrm{CaSO}}_4.\frac{1}{2}{\mathrm{H}}_2\mathrm{O}$)
which is known as the Plaster of Paris.

Chemical equation:

${\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}+\mathrm{Heat}\to {\mathrm{CaSO}}_4.\frac{1}{2}{\mathrm{H}}_2\mathrm{O}+1\frac{1}{2}{\mathrm{H}}_2\mathrm{O}$

Precautions to be taken while preparing the Plaster of Paris:

1. Gypsum should be prepared at a constant temperature of 373K, it shouldn't exceed the temperature.
2. If we exceed the temperature Gypsum loses the water of crystallization and anhydrous Calcium Sulfate( ${\mathrm{CaSO}}_4$) will be formed.