Question

Why anhydrous copper sulphate is colourless and blue vitriol is coloured?

Answer 1

Here's ur answer mate!!

This can be explained on the basis of Crystal field theory. In hydrated CuSO4 the water molecules surrounding the Central metal (Cu) function as ligands which bring d-d transition and hence emits blue colour in visible region due which hydrated CuSO4 appears blue and as anhydrous CuSO4 doesn't have any water of crystallisation hence remains white in colour.

HOPE IT HELPS!!

Answer 2

Answer:

Anhydrous copper sulphate is colourless and blue vitriol is coloured because

• Blue colour characterises hydrated copper sulphate, CuSO4 5H2 O. Splitting of d orbitals is brought about by the ligand (water) molecule. It also helps with colour and the d-d transition.
• CuSO4 is a colourless anhydrous copper sulphate. Splitting of d orbitals is impossible in the absence of ligand molecules (water molecules). In light of this, the d-d transition is not feasible.

• A ligand is an ion or molecule that attaches to the main metal atom to create a coordination entity or complicated compounds.
• The number of binding sites with the central metal atom, charge, and size is used to classify ligands.
• Covalent and ionic bonds are two different types of bonding that can exist between a metal and its ligand.
• An electron or electrons are said to undergo a d-d transition when they move from a lower energy d orbital to a higher energy d orbital through the absorption of energy, and vice versa.
• The electrical transition from a t2g orbital to an Eg orbital happens in complex compounds, such as an octahedral complex. Additionally, this transition usually involves energy in the visible domain, resulting in the observation of colours.

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