Question

Name the water-attracting ionic groups in (a) a soap (b) a detergent

Answer 1

(a)

• Soap is a Sodium or Potassium salt of a long chain of fatty acid (containing 15-18 Carbon atoms)
• Soap consists of two parts, polar and non-polar.
• The polar part is ${\mathrm{COO}}^{-}{\mathrm{Na}}^{+}$ and it is water-soluble.
• Non-polar part is a hydrocarbon chain consisting of 12 to 18 carbon atoms and this part is water-repellent.
• Therefore, the water-attracting group in soap is the Polar part ( ${\mathrm{COO}}^{-}{\mathrm{Na}}^{+}$)

(b)

• Detergent is Sodium salt of Sulphonic esters.
• A synthetic detergent has two parts, a hydrocarbon chain which is water repellent, and an acidic or basic group that is water-attracting.
• Therefore, an acidic or basic ionic group in detergent is water-attracting.