Question

In acidic medium potassium dichromatic acts as an oxidant according to the equation,
$C{r}_2{O}_7^{2-}+14H^{+}+6e^{-}\to 2C{r}^{3+}+7H_{2}O$.
What is the equivalent weight of $K_{2}C{r}_2{O}_7$? (Molecular weight $=M$)

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

Answer 1

The correct option is D $M/6$

The oxidation state of chromium is changed from $+6$ to $+3$

Reaction :

$C{r}_2{O_2}^{-7}+14H^{+}+6e^{-}\to 2C{r}^{3+}+7H_{2}O$

According to the given reaction for the above change $6e^{-}$ are involve,

Since the equivalent weight is $\frac{M}{6}$