Acids, Bases and Salts

Quickly browse through questions and notes on related topics. You can also download and read this topic offline.

• Questions
• Summary

Copper sulphate crystals which seem to be dry contain water of crystallisation. When we heat the crystals, this water is removed and the salt turns white.

Plaster of Paris (Calcium sulphate hemihydrates) (CaSO₄.½H₂O) :

On heating gypsum (CaSO₄.2H₂O) at 373K, it loses water molecules and becomes Plaster of Paris (POP).

It is a white powder and on mixing with water it changes to gypsum.

CaSO₄.½H2O + 1½H₂O → CaSO₄.2H₂O

Uses :

1. Doctors use POP for supporting fractured bones.
2. For making toys, material for decoration.
3. For making surfaces smooth.