Question

In acidic medium, H₂O₂ changes \[\ce{Cr2O^{2-}_7}\] to CrO₅ which has two (-O-O-) bonds. Oxidation state of Cr in CrO₅ is ______.

Options

• +5

• +3

• +6

• −10

Answer 1

In acidic medium, H₂O₂ changes \[\ce{Cr2O^{2-}_7}\] to CrO₅ which has two (-O-O-) bonds. Oxidation state of Cr in CrO₅ is +6.

Explanation:

The compound CrO₅ is chromium pentoxide, also called chromium peroxide. It contains one Cr atom and 5 oxygen atoms. Out of the 5 oxygen atoms, 4 oxygen atoms are part of 2 peroxo groups (-O-O-), each contributing −1 oxidation state. The remaining 1 oxygen atom is a normal oxide (O²⁻) with −2 oxidation state. The oxidation state of Cr is:

x + 2(−1) + (−2) = 0

⇒ x − 4 = 0

⇒ x = +6