Question

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.

Answer 1

Soaps are salts of sodium or potassium of higher fatty acids. Whereas detergents are ammonium or sulphonate salts of long chain carboxylic acids. Cleaning action of soap The cleaning action of soap is due to micelle formation and emulsion formation. Inside water a unique orientation forms clusters of molecules in which the hydro phobic tails are in the interior of the cluster and the ionic ends on the surface of cluster. This results in the formation of micelle. Soap in the form of micelle cleans the (dirt) oil as the oil will be collected at the centre of micelle.This property of soap makes it an emulsifier. The dirt suspended in micelles is easily rinsed away. This is known as cleaning action of soap. Dis advantage of soap When soap is mixed with hard water the calcium and magnesium salts displaces the salts of sodium and potassium present in the soap and forms scûm which is not soluble. Hence soaps are not effective in hard water for washing clothes. De merits of detergents (i)Detergents are not bio degradable. (ii)As the detergents are non biodegradable they cause environmental pollution like water and soil pollution. Disadvantage of soap When soap is mixed with hard water the calcium and magnesium salts displaces the salts of sodium and potassium present in the soap and forms scûm which is not soluble. Hence soaps are not effective in hard water for washing clothes. De merits of detergents (i)Detergents are not bio degradable. (ii)As the detergents are non biodegradable they cause environmental pollution like water and soil pollution.