Question

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

Answer 1

Blue vitriol is an older name for copper(II) sulphate. It is an inorganic compound and was also known as blue stone, vitriol of copper and Roman vitriol.

Complete step-by-step answer: The most common form of blue vitriol is pentahydrate copper sulphate. Pentahydrate copper sulphate has a chemical formula $CuS{O_4}.5{H_2}O$.
It is bright blue in colour. Copper sulphate pentahydrate possess the ability to exothermically dissolve in water in order to give aquo complex ${[Cu{({H_2}0)_6}]^{ + 2}}$ that has octahedral molecular geometry.
The structure of solid pentahydrate shows a polymeric structure where copper is octahedral and bound to four water molecules. The Cu(ll) and ${({H_2}O)_4}$ centres are interconnected by sulfate anions to form chains. Copper sulphate pentahydrate has 5 molecules of water which are also known as water of crystallization.
When penta hydrated copper sulphate or blue vitriol is heated, it loses its water of crystallization, that is, it loses water molecules attached to it. When pentahydrate copper sulphate is heated till ${100^ \circ C}$ it loses four water molecules of crystallization. At ${230^ \circ } C$, it loses a fifth molecule of water and becomes anhydrous copper sulphate. This anhydrous copper sulphate is amorphous in nature; it again becomes blue in presence of water.
Copper sulphate or sulfate is industrially produced by treating copper with hot concentrated sulphuric acid.

Note: The uses of copper sulphate are as follows,
1.It is used as a fungicide and herbicide by farmers.
2.It is beneficial as an analytical reagent; many chemical tests use copper sulphate.
3.Copper sulphate is used as a dehydrating agent.
4.It is used in electronics: copper sulphate is used in liquid resistors.