Question

What happens when gypsum is heated to 100°C (373 K)?

Answer 1

When gypsum is heated to 100°C (373 K), it loses three-fourths of its water of crystallisation and forms plaster of Paris.

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