Question

Why is sodium stored under kerosene?

Answer 1

Sodium is an alkali metal and it is placed in the ${1^{st}}$ group and ${3^{rd}}$ row of the periodic table. So, it will react with the atmosphere as other alkali metals do. Kerosene is just a compound which contains a mixture of short chain hydrocarbons.

Complete answer:
Sodium is an element that is placed in the ${3^{rd}}$ row of the periodic table and it is an alkali metal. All the alkali metals have an unpaired electron in its outermost orbital and so all of them are very reactive as they can donate that electron and make new compounds. Sodium is also very reactive.
- Now, generally we store most of the metals in any place because they do not react with containers or atmosphere. Sodium when allowed to be in contact with atmospheric air, it reacts with oxygen as well as moisture and carbon dioxide to give different products. That means we cannot store it in a way that it comes in contact with air. The reactions of sodium metal with atmospheric oxygen and carbon dioxide is as under.

$4N{a_{(s)}} + {O_{2(g)}} \to 2Na{O_{(s)}}$
$2N{a_{(s)}} + 2C{O_{2(g)}} + 2{H_2}{O_{(g)}} \to 2NaHC{O_3}_{(s)} + {H_{2(g)}}$

- We can either put it into a vacuum atmosphere or into some liquid that will not allow the sodium to react with the atmosphere. Now, in regular use, storage of sodium in vacuum cannot be done because it is very expensive and will not be easy to use. So, the only option is to use a liquid that can store this metal without reacting.
- All the alkali metals react with water violently to give their hydroxides and produce excessive amounts of heat because the reaction that occurs there is exothermic. That means we cannot store it in water as well. Its reaction with water is given here.

$2Na + 2{H_2}O \to 2NaOH + {H_2}$

Then any other liquid that is easily available and not reactive with sodium can be used as its storing solution. Hydrocarbons are not reactive towards most of the compounds so as sodium.
- We can use any hydrocarbon nut kerosene is the cheapest and easily available hydrocarbon. We can store and use sodium metal in the solution of kerosine with ease. That’s why sodium and other alkali metals are usually stored in kerosene.

Note: Do not expect that as other metals can be stored in open air containers, sodium can also be stored in that way. Remember that it cannot be stored in them because it reacts with them. While writing the answer to this type of question, make sure that you also give the reasons why it cannot be stored in other places and why the given solution is the best choice of storing it.