Both soap and detergent are some type of salts. What is the difference between them ? Describe in brief the cleansing action of soap. Why do soaps not form lather in hard water ? List two problems that arise due to the use of detergents instead of soaps.
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Answer:
Soap molecules are sodium or potassium salts of long-chain carboxylic acids whereas detergent molecules are ammonium or sulphonate salts of long-chain
carboxylic acids. Cleansing action of soaps: The dirt present on clothes is organic in nature and is insoluble in water. Therefore, it cannot be removed by only washing with water. When soap is dissolved in water, its hydrophobic ends attach themselves to the dirt and remove it from the cloth. Then, the molecules of soap arrange themselves in micelle formation and trap the dirt at the centre of the cluster. These micelles remain suspended in the water and, thus, the dust particles are easily rinsed away by water. Soaps do not form lather in hard water because soap molecules react with calcium and magnesium ions present in hard water to form insoluble substance, called scuum which remains after washing in water. Problems that arise due to the use of detergents instead of soaps are as follows: a) Being non-biodegradable in nature, they get accumulated in the environment and cause soil and water pollution. b) Their entry into the food chain leads to bio-accumulation in living beings and causes several health issues.