Question

If $N$ is the Avogadro number and $e$ is the electronic charge then the Faraday constant $F$ is equal to

• A. $Ne$
• B. $N^{2}e$
• C. $\frac{N}{e}$
• D. $\frac{e}{N}$

Answer 1

The correct option is A $Ne$

Faraday's constant is the amount of charge required to liberate 1 Kg equivalent of any substance by electrolysis. Hence, to liberate 1 Kg atoms of the substance, the amount of charge needed is FV, where V is the valency of the substance.

According to Avagadro's hypothesis, the number of atoms in 1 Kg of substance are N($\approx 6.02\times {10}^{26}$), where N is Avagadro's number.

Therefore, the charge required to liberate one atom of a substance is $\frac{FV}{N}$.

In electrolysis, ions give their charge to electrode and becomes atoms. Hence, charge on each ion is Ve, where, e is the charge on an electron. From above we can write,

$\frac{FV}{N}=Ve$

$\Rightarrow F=Ne$