When H₂O₂ is added to an ice-cold solution of acidified potassium dichromate in ether and the contents are shaken and allowed to stand:
Correct answer: B. A blue colour is obtained in ether due to formation of CrO5
- A. A blue colour is obtained in ether due to formation of Cr2(SO4)3
- B. A blue colour is obtained in ether due to formation of CrO5
- C. A blue colour is obtained in ether due to formation of CrO3
- D. Chromyl chloride is formed
Explanation
This is a characteristic test for chromates. In the presence of acid and H₂O₂, the dichromate ion is converted into chromium(VI) peroxide, CrO(O₂)₂, often written as CrO₅. This unstable compound has a distinctive deep blue color and is soluble in ether.
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