Question

Two electrolytic cells one containing acidified ferrous chloride and another acidified ferric chloride are connected in series. The ratio of iron deposited at cathodes in the two cells when electricity is passed through the cells will be _____.

• A. $3:1$
• B. $2:1$
• C. $1:1$
• D. $3:2$

Answer 1

The correct option is D $3:2$

In ${FeCl}_2$, ${Fe}^{+2}$ is present

& in ${FeCl}_3$, ${Fe}^{+3}$ is present

At cathode$:-{Fe}^{+2}+{2e}^{-}⟶Fe-\left(i\right)$

${Fe}^{+3}+{3e}^{-}⟶Fe-\left(ii\right)$

Equivalent weight of $Fe$ in $\left(i\right)=\frac{Atomicweight}{n}=\frac{Atomicweight}{2}$

Equivalent weight of $Fe$ in $\left(ii\right)=\frac{Atomicweight}{3}$

$\therefore$ Ratio of iron deposited at cathodes$=\frac{A/2}{A/3}=3:2$