What is the chemical formula of Plaster of Paris, a widely used building material and medical casting compound formed by the controlled heating of gypsum?

💡 Solution & Explanation

Plaster of Paris is chemically calcium sulfate hemihydrate, represented by the formula calcium sulfate bonded to half a molecule of water per formula unit, produced by heating gypsum to about 373 kelvins. Gypsum itself is calcium sulfate dihydrate, containing two water molecules of crystallization. When mixed with water, Plaster of Paris sets into a hard solid mass by re-forming gypsum. Cement manufacture involves burning limestone and clay at high temperatures.