Question

Which of the following reactions is possible at anode?

• A. $2C{r}^{3+}+7H_{2}O\to C{r}_2{O}_7^{2-}+14H^{+}$
• B. $F_2\to 2F^{-}$
• C. $\frac{1}{2}{O}_2+2H^{+}\to H_{2}O$
• D. None of the above

Answer 1

Answer: (A)

$2C{r}^{3+}+7H_{2}O\to C{r}_2{O}_7^{2-}+14H^{+}$

At anode, oxidation of metal takes place (or release of electron)

in option A, $C{r}^{3+}$ is changing its state from +3 to +6,

so the reaction takes place as

$C{r}^{3+}\to C{r}^{6+}+3e^{-}$

so, this reaction is possible at anode.