Question

An electric current of $1amp$ is passed through acidulated water 160 minutes and 50 seconds. What is the volume of the hydrogen liberated at the anode (as reduced to NTP)?
(A) 1.12 litre
(B) 2.24 litre
(C) 11.2 litre
(D) 22.4 litre

Answer 1

A balanced electrochemical equation of electrolysis of water is constructed in order to determine the amount of hydrogen being liberated due to fundamental current. Then, the amount of hydrogen produced is calculated for the given amount of current.

Complete step by step answer:
We will at first look up at faraday’s laws of electrolysis.
Faraday’s laws of electrolysis define there exists a definite relationship between the amounts of products liberated at the electrodes and the quantity of electricity used in the process.
1st law : The amount of given product, liberated at an electrode during electrolysis is directly proportional to the quantity of electricity passed through electrolyte.
2nd Law: When the same quantity of electricity passes through different electrolytes the amounts of substances liberated at electrode are directly proportional to chemical equivalent.
i.e. $W = Z \times C \times t$
$W \to$ mass of substance deposited.
$C \to$ Current
$Z \to$ equivalent weight
$t \to$ time
According to question,
We have,
$W = \dfrac{{Z \times I \times t}}{{2 \times 96500}}$
No. of moles $= \dfrac{W}{Z} = \dfrac{{I \times t}}{{2 \times 96500}}$
No. of moles $= \dfrac{{1 \times 9650}}{{2 \times 96500}}$
$= 0.05{\text{ moles}}$
As per question, it requires NTP condition.
So, 1 Mole of gas at NTP = 22.4 L
Hence, Volume of 0.05 moles of hydrogen liberated is
$= 22.4 \times 0.05$
$= 1.12L.$

So, the correct answer is Option A

Note:
Formula for calculating the amount of substance liberated at certain electrodes should be correctly used and proper care of units of NTP/STP conditions should be taken.where NTP stands for normal temperature pressure and STP standard temperature pressures.