Question

$C{r}_2{O}_7^{2-}\stackrel{H^{+}}{\to }C{r}^{3+}$
Equivalent weight of $C{r}_2{O}_7^{2-}$ is:

• A. $M/6$
• B. $M/3$
• C. $M/4$
• D. $M/2$

Answer 1

The correct option is A $M/6$

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

Let $M$ be the mass of chromate.

Change in oxidation state of $Cr$ is $+6$ to $+3$.

$C{r}_2{O}_7^{2-}+14H^{+}+6e^{-}\to 2C{r}^{3+}+7H_{2}O$

$\therefore 6e^{-}$ are involved.

Hence, Equivalent weight of $C{r}_2{O}_7^{2-}$ is $\frac{M}{6}$