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Coordination Compounds

Question
CBSEENCH12007508

Explain the following:
Violet coloured [Cr(H2O)6]3+ becomes bright blue when reduced to [Cr(H2O)6]2+

Solution
[Cr(H2O)6]3+ violet coloured changes to blue coloured [Cr(H2O)6]2+ when reduced because its Δ0 gets lowered and due to which in place of yellow region absorbed by [Cr(H2O)6]3+ now orange red region is absorbed and hence [Cr(H2O)]2+ become blue as blue is the complementary colour of orange.