Question

(a) What is gypsum? What happens when gypsum is heated to 100°C (373 K)?
(b) Name a sodium compound which is used for making borax and glass.
(c) Name the compound which is used in hospitals for setting fractured bones.
(d) Which is the real bleaching agent present in bleaching powder?

Answer 1

(a) Gypsum is calcium sulphate dihydrate (CaSO₄.2H₂O). When gypsum is heated to a temperature of 100^⁰C (373K), it loses three-fourths of its water of crystallisation and forms plaster of Paris (CaSO₄.1/2H₂O).

(b) Sodium carbonate or washing soda is used for making borax and glass.

(c) Plaster of Paris sets into a hard mass on addition of water. It is easy to mould a layer Plaster of Paris around the damaged part, which later solidifies and provides support to the damaged bone for its quick healing. This is why it is used in hospitals for setting fractured bones.

(d) Chlorine is the real bleaching agent present in bleaching powder.