Question

38.6 A of current is passed for 100 s through aqueous CuSO4 using platinum electrodes. Find mass of Cu deposited and volume of gas evolved (Cu = 63.54 g mol-1)

• A. 6.37 g, 0.448 L
• B. 0.63 g, 0.224 L
• C. 1.27 g, 0.224 L
• D. 4 g, 0.448 L

Hint:

Use Faraday's laws: $\text{mass} = \dfrac{EQ}{F}$ and volume of gas from $22.4 \times \dfrac{Q}{nF}$.

Answer 1

The Correct Option is C

Charge passed = I × t = 38.6 × 100 = 3860 C
1 mole of Cu (63.54 g) requires 2 × 96500 = 193000 C
So Cu deposited = $\dfrac{3860}{193000} \times 63.54 \approx 1.27$ g
For gas: 1 mol gas = 22400 mL = 22.4 L
Gas volume = $\dfrac{3860}{96500} \times 22.4 \approx 0.224$ L