The compound prepared from gypsum on heating it at 100oC, is known as plaster of Paris. Its chemical formula is CaSO4. 1/2H2 Hence, its chemical name is calcium sulphate hemihydrate. The chemical equation for its preparation is as follows:

Plaster of Paris is used in hospitals mainly as plaster for supporting fractured bones in the right position. In dentistry, it is used for making casts