Question

Using given sample of temporary and permanent hard water, soft water, ordinary soap, detergent and washing soda how would you prove the advantage of detergent over soap.

Answer 1

Experiment
Advantage of using detergents over soap

1. A sample of hard water ‘X’ is taken and ordinary soap is rubbed water.
2. Another sample of hard water ‘Y’ is taken and detergent is rubbed water.
   [Detergents are sodium salts of sulphonic acid and do not form scum.] Observation
3. Lather forms in ‘Y’ but not in ‘X’.

Result

1. Detergents from lather even with hard water, while ordinary soap is wasted due to formation of scum.

\[\ce{\underset{\text{[in hard water]}}{Ca(HCO3)2} + \underset{\text{[soap]}}{2NaSt} ->\underset{\text{[scum]}}{Ca(St)2↓} + 2NaHCO3}\]