A solution of $CuSO_4$ is electrolyzed for 1 minute with a current of 1 ampere. Given the atomic mass of Cu as $63\, g\, mol^{-1}$, the mass of copper deposited at the cathode is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (1890/ F) g
We can calculate the mass of copper deposited using Faraday’s laws of electrolysis.
Given:
- Current, $I = 1 \, \text{A}$
- Time, $t = 1 \, \text{min} = 60 \, \text{s}$
- Atomic mass of Cu, $M = 63 \, \text{g/mol}$
- Cu²⁺ → Cu (2 electrons, $n = 2$)
Step 1: Charge passed
$Q = I \cdot t = 1 \times 60 = 60 \, \text{C}$
Step 2: Moles of electrons
$\text{Moles of electrons} = \frac{Q}{F} = \frac{60}{F}$
Step 3: Moles of Cu deposited
$\text{Cu}^{2+} + 2e^- \to \text{Cu}$
$\text{Moles of Cu} = \frac{\text{Moles of electrons}}{2} = \frac{60}{2F} = \frac{30}{F} \, \text{mol}$
Step 4: Mass of Cu deposited
$m = n \cdot M = \frac{30}{F} \times 63 = \frac{1890}{F} \, \text{g}$