Question

In a redox reaction, dichromate ion $\left({C{r}_2{O}_7}^{2-}\right)$ is reduced to $C{r}^{3+}$ ion, the equivalent mass of $K_{2}C{r}_2{O}_7$ in this reaction is:

• A. $\frac{\text{molecular mass}}{3}$
• B. $\frac{\text{molecular mass}}{6}$
• C. $\frac{\text{molecular mass}}{1}$
• D. $\frac{\text{molecular mass}}{2}$

Answer 1

Answer: (B)

$\frac{\text{molecular mass}}{6}$

$C{r}_2{O}_7^{2-}+14H^{+}+6e^{-}\to 2C{r}^{3+}+7H_{2}O$
Change in oxidation number $=6$
$\therefore$ Equivalent mass $\frac{\text{molecular mass}}{6}$.