Question

What is Blue Vitriol? Write effect of heat on it.

Answer 1

Blue Vitriol is Penta hydrated copper sulphate. On heating at ${100}^{o}C$ it loses 4 molecules of crystallization. At ${230}^{o}C$, it loses $5^{th}$ molecules of water and becomes white amorphous powder. The powder again becomes blue in presence of water. It undergo dissociation on strong heating.

$CuS{O}_{4}5H_{2}O\stackrel{{100}^{o}C}{\to }CuS{O}_4.H_{2}O+4H_{2}O$

Pentahydrated Monohydrated

copper sulphate copper sulphate

$CuS{O}_4.H_{2}O\stackrel{{230}^{o}C}{\to }CuS{O}_4+H_{2}O$

Anhydrous copper

sulphate

$CuS{O}_4\stackrel{{730}^{o}C}{\to }CuO+S{O}_3$