Question

when we put Cuso4 in water after sometime we find that the solution turns blue. why? also on heating it what change will occur

Answer 1

Copper sulfate salt readily absorbs water from the air causing it to turn blue. If water is evaporated from these salts the color becomes white.

Copper sulfate is a deliquescent solid which readily absorbs water just like table salt.

Normally a molecule of copper sulfate has 5 molecules of water attached to it thus changing it's color to blue. It has similar property to copper nitrate.

Answer 2

Pure cuso4 is white in colour which is anhydrous.
When it is dissolved in water it gains the water of crystallisation i. e 5H2O which makes it hydrated and it turns out blue.
Hope that helps you :-)