Question

In acidic medium (Conc. H₂SO₄),Hydrogen peroxide reacts with K₂Cr₂O₇ in the presence of ether forms a deep violet coloured chromium peroxide. The Oxidation state of chromium in chromium pentoxide is

• A. +2
• B. +3
• C. +5
• D. +6

Answer 1

The correct option is D

+6

H₂O₂→ H₂O + [O]

K₂Cr₂O₇ +4[O] → H₂Cr₂O₇ +K₂SO₄

H₂Cr₂O₇ +4[O] →2CrO₅ +H₂O

4CrO₅ +6H₂SO₄ → 2Cr₂(SO₄)₃ +6H₂O +7O₂

CrO₅ is blue in colour and has a butterfly structure. There are 2 peroxy linkages on either side of the Cr and one Cr=O bond.