Question

A blue colour salt becomes white on heating. Give reason for the above observation.

What happens when we add water to the salt which is obtained after heating? Also

write its formula.

Answer 1

The blue salt is CuSO4.7H2O
When it is heated it loses its water molecules and turns white.
When water is added again the blue colour reappears and you get the blue salt again..
Hope it helps....

Answer 2

Hi Naseehanazer !!

Here's the answer to your question :-

The blue colour salt is none other than hydrated copper sulphate crystals which, on heating , loses its water of crystallisation and forms white coloured anhydrous copper sulphate.

CuSO4.5H2O (s) (Heat)=>CuSO4(s)+5H2O

Now , when we add water to anhydrous copper sulphate, its colour changes to blue. This shows that coloured hydrated copper sulphate has been regained.

CuSO4(s)+5H2O =>CuSO4.5H2O (s)

Hope that helped you friend!!