Question

Mention any two differences between soap and synthetic detergent.

Answer 1

Hint: Both soap and synthetic detergent are used in our daily lives. Both of these are used as cleansing agents. Start the question by explaining what soap and synthetic detergent is and then state the differences.

Complete step by step answer:
Both soap and synthetic detergent improve the cleansing properties of water. They also help in removal of fats which bind other materials to the fabric or skin. Detergents are sodium salt of a long-chain linear alkyl benzene sulphonic acid. These are manufactured chemically from materials other than animal fats. They can be used both in soft and hard water as they give foam even in hard water.

• General properties-
Soaps are made up of sodium or potassium salts of higher fatty acids, containing as much as 15-18 carbon atoms (for e.g., stearic acid, oleic acid and palmitic acid),are known as hard soaps are made up of Sodium salts of fatty acids whereas, soft soaps are made up of potassium salts of fatty acids.
Synthetic detergents, on the other hand, are usually alkylbenzene sulfonates.
Soaps are biodegradable whereas synthetic detergents are not.

• Uses-
Synthetic detergents can be used in soft as well as hard water since they give foam even in hard water. Soap does not lather well in hard water.
Another difference being - we can use soap on our skin. Synthetic detergents, if used on skin, can lead to irritability and itchiness.

Additional information:
A molecule of soap contains sodium or potassium salts of long-chain carboxylic acids. The carbon chain dissolves in oil and the ionic end dissolves in water. Therefore, the soap molecules form structures called micelles. In micelles, one end is an oil droplet and the other end is the ionic. The ionic side faces outside. Therefore, it forms an emulsion in water and helps in dissolving the dirt while we wash clothes.

Note: Cleansing agents are also known as surfactants. The molecules of a surfactants contain two characteristics group –
• Water Soluble (also called Hydrophilic)
• Oil Soluble (also called Lyophilic or Lipophilic).