Q.How are synthetic detergents better than soaps ?

Soaps and synthetic detergents both act as cleansing agents, but synthetic detergents have practical advantages over soap:

• Work in hard water — hard water contains dissolved $Ca^{2+}$ and $Mg^{2+}$ ions. Soap reacts with these to form an insoluble precipitate (scum), wasting soap and giving poor lather. The calcium/magnesium salts of synthetic detergents (e.g., sulphonates), however, remain soluble in water, so synthetic detergents continue to lather and clean effectively even in hard water.
• Work in acidic medium — soap (a salt of a weak fatty acid) is decomposed/precipitated by strong mineral acids, but many synthetic detergents can be formulated to work even in acidic solution. …

Compare soap and synthetic detergent behaviour in hard water (precipitate/scum vs. soluble salts) and in acidic conditions. State t …

• Saying synthetic detergents are 'stronger cleaners' without explaining the hard-water/acid chemistry reason. …