Question

Aman was heating blue vitriol in a testtube and after a while it became white coloured amorphous substance. Give reason.
[2 Marks]

Answer 1

Blue vitriol(hydrated copper sulphate) is an example of hydrated salt. It has the chemical formula ${\text{CuSO}}_4.5{\text{H}}_2\text{O}$. As we heat hydrated copper sulphate, the water molecules escape out of the salt as water vapour.
[0.5 Marks]
We are left with the white amorphous copper sulphate salt which is an anhydrous salt.
[0.5 Marks]
${\text{CuSO}}_4.5{\text{H}}_2\text{O}\text{(s)}\stackrel{\text{Heat}}{\to }{\text{CuSO}}_4\text{(s)}+5{\text{H}}_2\text{O}\text{(g)}$
[1 Mark]