Question

why copper sulphate is not kept in iron vessel

Answer 1

copper sulphate is not kept in iron vessels because iron being more reactive than copper displaces it form copper sulphate forming ferrous sulphate and copper. in short,displacement reaction will take place.

 CuSO4 (aq) + Fe (s) -------> FeSO4 (aq) + Cu (s)

Answer 2

This is because Iron can react with Copper Sulphate.
Iron being more reactive, displaces Cu from CuSO4 forming FeSO4 and Cu.
This is an eg of displacement reaction.

                      CuSO4   +    Fe     →         Fe SO4    + Cu