Question

a blue colour salt becomes white on heating give reason for above observation.what happens when we add water to the salt which is obtained after it write formula

Answer 1

The blue salt is copper sulphate penta hydrate
ie Cuso4. 5h20.

When we Heat it 5h2o gets evaporated and we got white Cuso4.

When we add water again it gains 5h2o and becomes blue again.

Thanks for asking

Answer 2

Because when copper sulphate is heated it loses 5 molecule of water and become white in colour .

When we add water the copper sulphate will have 5 water molecule and become blue in colour .

Cuso4.5H2O