Question

Both soap and detergent are some type of salt. What is the difference between them? Describe in brief the cleansing action of soap. Why do soap not form lather in hard water? List two problems that arise due to the use of detergents instead of soaps.

Answer 1

Hint : Soaps are salt of sodium or potassium of long chain of carboxylic acids while detergent are salt of ammonium and sulphate of long chain of carboxylic acids. Soaps have very weak cleaning action while detergents show strong cleaning actions.

Complete step by step solution:
> The cleaning action of soap- The dirt on our clothes are organic in nature and insoluble in water. When the soap is dissolved in water, the hydrophobic end $(R$ group from long chain fatty acid) of the soaps attract oily or dirty particles. Then the soap molecules are arranged in a manner to form micelle and trap the dirty particle at the centre of micelle. Thus these micelle remains suspended in water and are removed by water.
> We know that hard water contains calcium and magnesium salts. Soap molecules form an insoluble precipitate called scum when reacts with calcium and magnesium salts thus soaps do not form lather in hard water.
> The two problems that arises due to the use of detergent instead of soaps are;
 (i) Some phosphate additives are added to detergents which nutrients for algae and forms a thick layer of green scum over the river and disturbs aquatic life.
 (ii) Soaps are biodegradable substances and do not harm nature while detergents are non-biodegradable which is harmful for the environment.

Note : Thus we have got information about cleaning action of soaps and how soap and detergents are different. Soaps are made of natural ingredients such as neem, coconut oil etc. while detergents are made of synthetic ingredients.