Question:
How many moles of iron will by passage of $\pu{4 A}$ of current through $\pu{1 L}$ of $\pu{0.1 M}$ $\ce{Fe^{3+}}$ solution for $1$ hour. Assume $\ce{Fe^{2+}}$ is not present in the solution initially.
Attempt:
Using Faradays' Law, we have:
$\text{mass delivered = } \mathrm {Z\times I\times t} = n\times M$ where $\mathrm Z = \dfrac{\text{Equivalent mass }}{\pu{1F}}$
Equivalent mass of Iron here would be $\dfrac{M}{3}$ where M is molar mass.
So,
$n \times M = \dfrac{M}{3}\times \dfrac{\pu{1 mol}}{\pu{96500 C}}\times \pu{4 \frac{C}{s}} \times \pu{60 \frac{s}{min}} \times \pu{60 \frac{min}{hr} \times \pu{1 hr}}$
$\implies n = 0.049$ moles.
But answer given is $\pu{0.0245 moles}$
Where have I gone wrong? I can't figure out why there's a difference of factor of 2 in the answer.