Question

How would you show that blue copper sulphate crystals contain water of crystallisation?

Answer 1

When copper sulphate crystals (chemical formula CuSO₄.5H₂O) are heated strongly, they lose all the water of crystallisation and form anhydrous copper sulphate (CuSO₄), which is white. As the blue colour of the crystals disappeared on heating, we can conclude that the colour was due to water of crystallisation. This proves that blue copper sulphate crystals contain water of crystallisation.                      

       CuSO₄.5H₂O →  CuSO₄ + 5H₂O