Question

When blue coloured copper sulphate crystals are heated their colour changes to white. When water is added, their colour again becomes blue. Give reason for your

Answer 1

When blue coloured copper sulphate crystals are heated their colour changes to white because of the loss of water of crystallization. When water is added to anhydrous copper sulphate it gains back its blue colour due to addition of water molecules.
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Answer 2

Answer:

when copper sulphate is heated for some time, the blue colour disappears and it becomes white-gray in colour. This is because the water molecules are lost on heating and copper sulphate pentahydrate is converted to anhydrous copper sulphate.