Question

The colour of the salt formed due to the removal of water crystals from hydrated copper sulphate upon heating is _________.

• A. green
• B. red
• C. orange
• D. white

Answer 1

The correct option is D white

The colour of crystalline salts is usually due to the presence of water of crystallization. When such a crystal is sufficiently heated, it loses its water of crystallization and usually the crystal loses its colour.

White colour salt is formed when blue colour hydrated copper sulphate is heated due to the removal of water molecule from the salt. The reaction occurs as follows:
${\text{CuSO}}_4.5{\text{H}}_2\text{O}\text{(s)}\stackrel{\text{Heat}}{\to }{\text{CuSO}}_4\text{(s)}+5{\text{H}}_2\text{O}\text{(l)}$