Question

In chromyl chloride test for confirmation of Cl-, a yellow solution is obtained. Acidification of the solution and addition of amyl alcohol and 10% H2O2​ turns organic layer blue indicating formation of chromium pentoxide. The oxidation state of chromium in that is

• A. $+6$
• B. $+5$
• C. $+10$
• D. $+3$

Answer 1

Answer: (A)

$+6$

Answer 2

- During the chromyl chloride test, the following reaction occurs:

Cl− + K2Cr2O7 + H2SO4 → CrO2Cl2 + Cl−

- In basic medium, this results in a yellow solution due to CrO42−.

- Upon acidification, addition of amyl alcohol, and 10% H2O2, a blue organic layer forms due to the formation of CrO5 (chromium pentoxide).

- The oxidation state of chromium in CrO5 is +6.

So, the correct answer is: +6