Question

Sodium metal should be stored under kerosene.Why?

Answer 1

Hint: We know that sodium is a very reactive metal and it reacts violently with oxygen to form sodium oxide but this is an unstable compound and soon reacts with hydrogen to form sodium hydroxide.

Complete step by step answer:

Sodium is kept in kerosene because it is a highly reactive metal. If it is kept in an open container, it will react with oxygen and water vapor present in the atmosphere producing sodium oxides and sodium hydroxides respectively which is a highly exothermic reaction.
It should be handled with care because it can react with moisture from our hands and can cause blisters. Kerosene oil does not react with sodium and acts as a barrier which restricts its reaction with oxygen and moisture.
The reaction of which can be mentioned below:
$\text{4Na + }{{\text{O}}_{2}}\to \text{2N}{{\text{a}}_{2}}\text{O}$
$\text{N}{{\text{a}}_{2}}\text{O+}{{\text{H}}_{2}}\text{O}\to \text{2NaOH}$
It should be noted that under normal conditions (room temperature and corresponding humidity/air pressure) kerosene doesn’t react with air or oxygen (due to high enough activation barrier for this reaction). Thus, in order to react with oxygen, kerosene requires either high enough temperature around ${{300}^{\text{o}}}\text{C}$under normal pressure or at lower temperatures (as low as${{60}^{\text{o}}}$C in the presence of a catalyst such as platinum etc.)

Note: Apart from that, sodium metal is very useful in our daily life. Sodium metal is used in the manufacture of soap. Most soap that we find today is salts of fatty acids. NaOH is also used in paper making. It helps in the regeneration of the chemicals that are used to pulp wood chips in the pulping process. Other than this, sodium hydroxide is also used in paper recycling as well as paper bleaching as an alternative for chlorine.