Chemistry - Electrochemistry Question with Solution | TestHub

In cell A, ferrous chloride (${\text{FeCl}}_2$) contains iron in the $+2$ oxidation state. The reduction reaction is:

${\text{Fe}}^{2+}+2e^{-}\to \text{Fe}$

The equivalent weight of iron in cell A is $E_A=\frac{M}{2}$, where $M$ is the atomic mass of iron.

In cell B, ferric chloride (${\text{FeCl}}_3$) contains iron in the $+3$ oxidation state. The reduction reaction is:

${\text{Fe}}^{3+}+3e^{-}\to \text{Fe}$

The equivalent weight of iron in cell B is $E_B=\frac{M}{3}$.

According to Faraday's second law of electrolysis, the mass of a substance deposited by the same quantity of electricity is directly proportional to its equivalent weight. Thus, the ratio of the mass of iron deposited in cell A to that in cell B is:

$\frac{m_A}{m_B}=\frac{E_A}{E_B}=\frac{\frac{M}{2}}{\frac{M}{3}}=\frac{3}{2}$

The ratio is $3:2$.

Answer: $3:2$