Question

How is plaster of Paris prepared? Write a chemical equation of the reaction involved.

Answer 1

Plaster of Paris is prepared by heating gypsum (CaSO₄.2H₂O) to a temperature of 100°C (373 K) in a kiln. When gypsum is heated to 100°C (373 K), it loses three-fourths of its water of crystallisation and forms plaster of Paris.

\[\ce{\underset{Gypsum}{CaSO4 * 2H2O} ->[Heat to 100^\circ C][(373 K)] \underset{Plaster of Paris}{CaSO4 * 1/2 H2O} + \underset{Water}{1 1/2 H2O}}\]