Introduction
In this science experiment, we will learn soap preparation.
Basic Building Concept
The reaction between ether and salt of carboxylic acid gives alcohol, and this reaction is called saponification.
Ether + Base → Alcohol + salts of carboxylic acid
This reaction is used for preparing soap.
Aim
To perform a saponification reaction for soap preparation.
Materials Required
1. Vegetable oil,
2. Sodium hydroxide pellets,
3. Common salt,
4. Distilled water,
5. Red and blue litmus strips,
6. Two beakers,
7. Two test tubes,
8. Glass rod,
9. Measuring cylinder (50 ml),
10. A knife,
11. Weight box,
12. Weighing bottle.
Theory
1. The nature of the saponification reaction is exothermic, i.e., heat is liberated from the reaction.
2. Soaps are made up of long sodium and potassium salt chains.
3. The reaction between triester oil/fat with sodium or potassium hydroxide gives out soap or salts of fatty acid glycerol.
Procedure
1. In 250ml of a beaker, take 25ml of vegetable oil.
2. In another beaker, take 10g of NaOH and 50ml of water. Stir it well to prepare a 20% solution of NaOH.
3. Add 30ml of NaOH solution to the first beaker(vegetable oil).
4. Take two litmus paper strips, red and blue, and dip them in the solution of NaOH and vegetable oil.
5. Note the change in colour of litmus paper.
6. Feel whether the beaker is hot or not by touching the beaker from the outside.
7. Add 10 grams of salt into the mixture and stir it well using the glass rod until the soap begins to set.
8. Leave this mixture undisturbed for one day so that the soap can set well.
9. After one day, take out the soap cake and cut it into various shapes using a knife.
Observations
1. Red litmus turned blue, and there was no change in blue litmus.
2. Beker got warm, which means heat is liberated from NaOH and vegetable oil solution.
Result
1. The soap formed is basic in nature.
2. Saponification is an exothermic reaction which means this reaction releases heat.
Precautions
1. Stir the solution of NaOH and vegetable oil enough.
2. Handle the solution of NaOH with utmost care.
Viva Questions With Answers
Q.1 What was the aim of our experiment?
ANS. To perform a saponification reaction for soap preparation.
Q.2 What do you understand by saponification reaction?
ANS. The reaction between ether and salt of carboxylic acid gives alcohol, and this reaction is called saponification.
Ether + Base → Alcohol + salts of carboxylic acid.
This reaction is used for preparing soap.
Q.3 What do you understand about soap?
ANS. Soap is the long-chain fatty acid of potassium and sodium salt.
Q.4 What is the name of the process through which soap is made?
ANS. Saponification.
Q.5 Write a saponification reaction.
ANS.
Q.6 Is saponification reaction endothermic?
ANS. No
Q.7 What do you mean by the endothermic reaction?
ANS. Those reactions from which the heat does not liberate out are endothermic reactions.
Q.8 What do you mean by the exothermic reaction?
ANS. Those reactions from which the heat liberates are known as endothermic reactions.
Q.9 What can we use instead of sodium hydroxide in a saponification reaction?
ANS. Potassium hydroxide
Q.10 What do you mean by fatty acid?
ANS. The long branched carboxylic acid, which contains saturated or unsaturated aliphatic tail, is known as a fatty acid.
Saquib Siddiqui is a Mechanical Engineer and a content creator. He has special interest in science experiments and teaches the same to school and college students. He is also a technical lead at RUDE LABS PVT. LTD.
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