Question

The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is (a) 1:1 (b) 2:1 (c) 4:1 (d) 1:2

Answer 1

Answer

b) 2:1

$\rule{100}2$

When electric current is passed through water, it decomposes water into oxygen and Hydrogen gas.

The following reaction will takes place-

$\sf{2H_2O\:\xrightarrow{\text{electricity}}\:2H_2\:+\:O_2}$

Electrolysis of water is a decomposition reaction. In which a single reactant break down into two or more products. Such type of reaction is known as Decomposition reaction.

Decomposition reaction is of three types.

• Thermal decomposition reaction
• Photo decomposition reaction
• Electric decomposition reaction

Electrolysis is a process in which electrical current flows in a liquid which causes chemical changes.

In electrolysis of water; oxygen gas is liberated at cathode (negatively charged) and hydrogen gas is liberated at anode (positively charged).

In this 2 moles of water decomposes into 2 moles of hydrogen gas and 1 mole of oxygen gas.

Ratio of moles of Hydrogen to Oxygen is 2 : 1 and ratio of moles of Oxygen to Hydrogen is 1 : 2.

Answer 2

Answer:

2:1

Explanation:

✍The water decomposes during electrolysis to form hydrogen and oxygen gases in the ratio 2:1 by volume.

[or]

✍Because Water's chemical representation is H₂O. That means, each water molecule has 2 hydrogen atoms & 1 oxygen atom. When electricity passes through water, the H₂O molecule breaks up into 2 Hydrogen & 1 oxygen atoms. So their ratio is 2 :1

2$H_2$O(l)➡2$H_2$(g)+$O_2$(g)

✍In a decomposition reaction, a compound is broken down into its simpler forms. During electrolysis water is broken down into oxygen gas and hydrogen gas due to passing of electric current through it.