Question

In the refining of silver by electrolytic method, what will be the weight of 100 g Ag anode if 5A current is passed for hours? The purity of silver anode is 95% by weight.

• A. 42.91 g
• B. 57.59 g
• C. 13.69g
• D. 36.38 g

Answer 1

Answer: (B)

Only pure Ag from the anode is oxidised, which in turn is deposited at cathode. By Faradays first law, weight of Ag deposited at cathode, $W=Zit$ $=\frac{108\times 5\times 2\times 3600}{1\times 96500}=40.29g$ but anode is 95% pure w.r.t., Ag. Hence, actual loss is $=40.29\times \frac{100}{95}=42.41g$ Weight of Ag-anode after electrolysis $=100-42.41=57.59g$