Question

In the electrolysis of water, Why is the volume of gas collected at one electrode double than the other?

Answer 1

The word electrolysis itself explains the process of electrolysis, in this process electricity is passed through a compound in order to create a chemical change in it. The compound is broken and it either gains or loses an electron.

Complete answer:
With a voltage of 1.23 a current is passed through the water. This process is generally done to obtain pure hydrogen or oxygen gas. When the current passes through the water it breaks up the molecule. In this process electrodes like platinum or palladium are used. When electrolysis occurs cathode is deposited with hydrogen while anode gets deposited with oxygen , but since in water molecules ${H_2}O$ there are $2$atoms of hydrogen and $1$ atoms of oxygen present. Hence the volume deposited on cathode is double than volume at anode. Since hydrogen gas released is double because of the two atoms present. The number of cations and anions present in the solution determine the efficiency of the process. Mobility of the ions is also a factor considered for efficiency. The reaction at cathode at a temperature of${25^ \circ }$ is as followed
$2{H_2}O + 2{e^- } \to {H_2}2O{H^ - }{E^\circ }$ $= - 0.42V$
Reaction at anode
$2{H_2}O \to {O_2} + 4{H^ + } + 4{e^ - }{E^\circ } = + 0.82V$

Note:
Electrolysis requires ions in order to pass electricity. If there are less numbers of ions present the process will be difficult. Hence electrolysis of pure water is difficult since ions present are low.