Question

What is soap? How can you make soap in the laboratory?

Answer 1

The sodium salts of acids are called soaps. A soap is prepared by boiling vegetable oil or fats from animals along with sodium hydroxide (NaOH).

We can prepare a soap in the laboratory by following the below mentioned procedure.

Required materials:

20ml of castor oil (we can also use coconut oil or any other oil)
Half teaspoon of sodium hydroxide pellets
1 teaspoon of common salt (sodium chloride), and
Glass rod for stirring

Procedure :

• Take the 20ml castor oil in a beaker.
• Mix ½ teaspoon of sodium hydroxide pellets with about 20ml of water to prepare the sodium hydroxide solution.
• Now, mix the oil with the sodium hydroxide solution.
• Heat the mixture and allow it to boil for about 5 to 10 minutes by constantly stirring it with the glass rod.

The oil will react with the sodium hydroxide solution to form soap and glycerine.

$\mathrm{Oil}+\mathrm{Sodium}\mathrm{hydroxide}\to \mathrm{Soap}+\mathrm{Glycerine}$

• The soap formed can be separated from the mixture by adding a tea spoon of common salt (sodium chloride) in the beaker.
• After cooling, the solid soap gets separated from the mixture by floating on the top. Thus, a soap is prepared in the laboratory.