Question

How much current should be passed through acidified water for 100 s to liberate 0.224 litre of \[{H_2}\]
A. 22.4 A
B. 19.3 A
C. 9.65 A
D. 1 A

Answer 1

Hint: First we need to change the given volume of the Hydrogen molecule to the number of atoms to be liberated. To find the total current we use Faraday’s law of electrolysis.

Formula Used:\[i = \dfrac{Q}{t}\], here I is the electric current, and Q is the amount of charge flow per unit of time.

Complete answer:At standard temperature and pressure conditions, 22.4 litre of any gas is equivalent to 1 mole of the gas.
So, 22.4 litre of \[{H_2}\]at standard temperature and pressure is equivalent to 1 mole of \[{H_2}\]
The atomicity of the Hydrogen molecule is 2, i.e. one molecule of Hydrogen atom contains 2 atoms of Hydrogen.
So, 1 mole of Hydrogen will contain 2 moles of the Hydrogen atom.
One hydrogen ion is liberated as a hydrogen atom by gaining 1 electron.
So, the total charge needed to liberate 22.4 litres of \[{H_2}\]is 2 moles of electron which is equivalent to 2F charge.
So, the charge needed to liberate 0.224 litres of \[{H_2}\]will be,
\[Q = \dfrac{{2F}}{{22.4}} \times 0.224 = 1930C\]
Using the definition of electric current, the electric current needed is,
\[i = \dfrac{Q}{t}\]
\[i = \dfrac{{1930}}{{100}}A\]
\[i = 19.3A\]
Therefore,

the correct option is (B).

Note: We should be careful while using 22.4 litre equivalence to 1 mole of gas. As it is valid for the standard pressure and temperature condition and unless the temperature and pressure are not mentioned in the question, we need to assume it to be standard pressure and temperature condition.