Why does copper sulfate pentahydrate change colour upon heating?

1 Answer
Nov 20, 2016

Because a chemical reaction has taken place, colour change is the prime means to determine the fact of chemical change (of course there are chemical reactions that proceed WITHOUT colour change).


And we can represent this reaction by the following chemical equation:

#underbrace(CuSO_4*5H_2O(s))_"beautiful blue"+Delta rightleftharpoons underbrace(CuSO_4(s))_"white salt" + 5H_2O(g)uarr#

Copper sulfate is different and distinct to copper sulfate pentahydrate; thus the salts should have different properties and different colours, and indeed they do.