Question

On heating, blue copper sulfate crystals become white.

Answer 1

• Copper sulfate crystals (CuSO₄.5H₂O) are blue due to the presence of water of crystallization.
• The water of crystallization means having a fixed number of molecules present in one formula of a unit of salt.
• On heating, it removes the water from crystallization making it anhydrous copper sulfate (CuSO₄).
• Therefore, the color changes from blue to white.
  CuSO₄.5H₂O (s) $\stackrel{∆}{\to }$ CuSO₄(s)+5H₂O (g)