Question

A certain charge liberates 0.8 gm of ${O_2}$. The same charge will liberate how many gm of silver
A) 108 gm
B) 10.8 gm
C) 0.8 gm
D) 108/0.8 gm

Answer 1

Hint: We have to use Faraday’s first law to solve this question. According to the first law, the amount of chemical change a current causes at an electrode-electrolyte contact is proportional to the amount of electricity consumed.

Complete step by step solution:The mass of the substance released or deposited on an electrode during electrolysis is directly proportional to the amount of electric charge carried through the electrolyte, according to Faraday's first law.
If m = mass of a substance liberated or deposited at an electrode and q = charge. Then according to Faraday's law of electrolysis,
$m \propto q \Rightarrow m = zq$
Where z = electrochemical equivalent of the substance. The z is calculated by the given equation.
$z = \dfrac{{Atomic~mass}}{{Valency}} \times \dfrac{1}{{96500}}gm{C^{ - 1}}$
The charge is same for both elements. The equations for the two cases will be,${m_1} = {z_1}q$ and ${m_2} = {z_2}q$. Now comparing the two equations and we will get,
$\dfrac{{{m_1}}}{{{m_2}}} = \dfrac{{{z_1}}}{{{z_2}}}$
\[{m_1}\] = mass of oxygen = 0.8 gm
\[{z_1}\] = electrochemical equivalent of oxygen = $\dfrac{{16}}{2} \times \dfrac{1}{{96500}} = \dfrac{8}{{96500}}gm{C^{ - 1}}$
\[{z_2}\] = electrochemical equivalent of silver = $\dfrac{{108}}{1} \times \dfrac{1}{{96500}} = \dfrac{{108}}{{96500}}gm{C^{ - 1}}$
\[{m_2}\] = mass of silver
$\dfrac{m_1}{m_2}=\dfrac{z_1}{z_2}=\dfrac{0.8}{m_2}=\dfrac{\dfrac{8}{96500}}{\dfrac{108}{96500}}$
$\dfrac{{0.8}}{{{m_2}}} = \dfrac{8}{{108}}$
${m_2} = \dfrac{{0.8 \times 108}}{8} = 10.8g$

Hence, the correct option is Option (B).

Additional Information:According to Faraday's second law of electrolysis, the masses of ions deposited at the electrodes are inversely proportional to their chemical equivalents when the same amount of electricity is applied to various electrolytes.
The Faraday constant represents the amount of electric charge carried by one mole, or Avogadro's number of electrons. It is a crucial constant in physics, electronics, and chemistry. The measurement is given in coulombs per mole (C/mol).

Note: Electrolysis is a technique for eliminating iron oxide. By applying a tiny electrical charge to the rusted metal from a battery or battery charger to stimulate ion exchange while the device is submerged in an electrolyte solution.