Explain reason for the following `CuSO_(4). 5H_(2)O` is blue while `CuSO_(4)`is colourless ?

Explanation

To explain why `CuSO4·5H2O` (hydrated copper(II) sulfate) is blue while `CuSO4` (anhydrous copper(II) sulfate) is colorless, we need to consider the role of water molecules and the electronic structure of copper ions.

### Step-by-Step Solution:

1. **Understanding the Compounds**:
- `CuSO4` is the anhydrous form of copper(II) sulfate, which does not contain any water molecules. It appears colorless because the copper ions in this state do not have any ligands that can cause electronic transitions.
- `CuSO4·5H2O` is the hydrated form, which contains five water molecules coordinated to the copper ions.

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