A chemical reaction is a process in which one or more substances (reactants) undergo chemical changes to form new substances (products) with different chemical properties.

Plaster of Paris is used for making casts and molds in medicine, particularly for setting fractured bones. It’s also used in dentistry, art and sculpture, construction for decorative purposes, and crafts such as model making and ornamentation.

In the chemical formula CaSO₄·1/2H₂O, only half a water molecule is shown because two formula units of CaSO₄ share one molecule of water during the formation of calcium sulfate hemihydrate.

Plaster of Paris reverts back to gypsum when mixed with water, forming a hard solid mass. This process involves the rehydration of calcium sulfate hemihydrate, restoring its original chemical composition.

When gypsum is heated at 373 K, it loses water molecules and transforms into calcium sulfate hemihydrate, also known as “Plaster of Paris.”