Question

Why copper sulphate is called blue vitriol?? Thank you.

Answer 1

Copper sulfate is a derivative of sulfuric acid, which was commonly called `"oil of vitriol..."`

Explanation:

And it could be produced from `"copper(II) oxide:"`

`CuO(s) + H_2SO_4(aq) rarr CuSO_4(aq) + H_2O(l)`

The sulfate salt, as the hexahydrate, i.e. `[Cu(OH_2)_6]^(2+)`, is a beautiful blue colour, and macroscopic crystals can be grown..hence `"blue vitriol"`.

kids.britannica.com

Note that anhydrous copper sulfate is WHITE...the colour derives from aquation of the cupric ion by water molecules...