Question

In a demonstration experiment, the teacher prepared the following solutions.

Solution 1 : ZnSO₄ in water

Solution 2 : CuSO₄ in water

1. Which of the above solutions is coloured?

2. Explain the Chemistry behind it.

Answer 1

(1). Solution 2 : CuSO₄ in water is coloured.

(2). In CuSO₄ , Cu is in +2 oxidation state. Cu²⁺ has 3d⁹ electronic configuration and it can undergo d-d transition and hence has colour(blue). In ZnSO₄, zinc is in +2 oxidation state. Zn²⁺ has the 3d¹⁰ configuration. It has no d-d transition and hence it is colourless.