In an acidic medium, reacts with to form , a blue compound which has two peroxy () bonds. What is th — Electrochemistry Chemistry Question
Question
In an acidic medium, $H_2O_2$ reacts with $Cr_2O_7^{2-}$ to form $CrO_5$, a blue compound which has two peroxy ($-O-O-$) bonds. What is the oxidation state of $Cr$ in $CrO_5$ and is the conversion of $Cr_2O_7^{2-}$ to $CrO_5$ a redox process for chromium?
Answer: B
💡 Solution & Explanation
The structure of $CrO_5$ features one double-bonded oxygen ($O^{2-}$) and four oxygen atoms in two peroxide linkages (each $O$ is $-1$). The sum of oxidation states is $x + (-2) + 4(-1) = 0 \implies x = +6$. In $Cr_2O_7^{2-}$, $Cr$ is also in the $+6$ oxidation state. Therefore, chromium does not undergo oxidation or reduction.
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