QS Study

Detergent is better than soap for the following reasons:

  • Soap does not work well in hard water since the Ca2+, Mg2+ ions of hard water react with soap forming insoluble substance. So, it creates unnecessary wastages of soap and also does harm to the fiber of the clothes.

RCOONa + Ca2+ —->(RCOO)2Ca

On the other hand, detergent works well both in hard acidic water and soft water, since detergent reacts with Ca2+, Mg2+ ions of hard water producing water soluble calcium or magnesium salts. So, no harm is done to the garments.

R-OSO3-Na+Ca2+ (R-O-SO3)2Ca

  • Detergent is more soluble in water than soap.
  • Detergent is active in acidic and basic media which soap cannot do.
  • Detergent is a better cleaning agent than soap.
  • Detergent can be equally used both in aqueous and ndn aqueous media.
  • Detergent can be used both in solid and liquid forms. But soap cannot use in such ways.

Nice to know:

  • Soap is the sodium and potassium salt of higher fatly acid. The general formula of soap is

R-COONa or R-COOK, R = 12 – 18 C

  • Detergent or synthetic clearing agent is the sodium salt of long chained alkyl/aryl hydrogen sulphate or sulphonate. The general formula of detergent is

R/Ar – SO4/SO3 – Na, R = 12 – 18 C