Question

The volume of gases obtained at the cathode at STP ($1$ bar and $273K$) when $1$ faraday of electricity is passed is

• A. $11.2$ litres
• B. $11.35$ litres
• C. $22.4$ litres
• D. $22.7$ litres

Answer 1

The correct option is B $11.35$ litres

At cathode, 1 mol $H_2$(g) is obtained by 2 faraday (since two electrons are used in the reduction).
2 faraday $\Rightarrow$ 1 mol of $H_2$ at STP (1 bar and 273 K)
1 faraday $\Rightarrow \frac{1}{2}$ mol of $H_2\Rightarrow \frac{1}{2}\times 22.7=11.35$ litres. So the answer is the option (B)
Note:
1. Volume of 1 mol of gas at STP (1 atmosphere, 273 K) = 22.4 litres
2. Volume of 1 mol of gas at STP (1 bar, 273 K) = 22.7 litres
3. Volume of 1 mol of gas at standard conditions (1 atmosphere, 298 K) = 24.4 litres
4. Volume of 1 mol of gas at standard conditions (1 bar, 298 K) = 24.7 litres