The chemical formula of Plaster of Paris (POP) is CaSO4.½ H2O.
Gypsum (CaSO4.2H2O) is formed on mixing POP with water as follows:
CaSO4.½ H2O + 1½ H2O → CaSO4.2H2O
Uses of POP:
In hospitals, as plaster for supporting fractured bones in the right position.
For making decorative materials and for making wall surfaces smooth.
As a fire-proofing material.