Plaster Of Paris

Plaster Of Paris

Definition
The hemi hydrate form of calsium sulphate is known as Plaster of Paris.
Molecular Formula
The molecular formula of Plaster of Paris is
CaSO4. 1/2 H2O
Preparation of Plaster of Paris
When Gypsum (CaSO4.2H2O) is heated to about 100ºC, it loses some water of crystallization and is converted to Plaster of Paris.
Uses of Plaster of Paris
1. At high temperatures gypsum loses all the water of crystallization to give anhydrous calsium sulphate.
2. It is used in manufacture of H2SO4.
3. It is used in making of cement.
4. It is used in the preparation of moulds used in surgery and castings.