Question

Cationic surfactants is/are:
(A) ${{C}_{17}}{{H}_{35}}COONa$
(B) ${{C}_{17}}{{H}_{35}}COOK$
(C) ${{C}_{17}}{{H}_{35}}S{{O}_{3}}Na$
(D) ${{C}_{16}}{{H}_{33}}N{{(C{{H}_{3}})}_{3}}Cl$

Answer 1

Hint: Cationic surfactants are classified under the category of surfactants. These consist of a long hydrocarbon chain, and a water-loving end. Now, identify the given options whether they are anionic, or cationic surfactants.

Complete answer:
-First, let us know about the cationic surfactants. These are types of soaps, or detergent, as mentioned falls under the category of surfactants. It consists of a hydrophilic part in the long hydrocarbon chain.
-It contains a positively charged ion, or from the name we can say a cation is attached to the hydrophilic part.
-Now, let us look at the given options, the first is ${{C}_{17}}{{H}_{35}}COONa$, it is named as sodium stearate, considered to be an anionic surfactant, as the functional group present at the head part is anionic in nature.

-The second option is ${{C}_{17}}{{H}_{35}}COOK$ , it is named as potassium stearate, and it also falls under the category of anionic surfactants.

-The third option we have i.e., it is named as sodium decanesulfonate ${{C}_{17}}{{H}_{35}}S{{O}_{3}}Na$, and it is also an anionic surfactant.

-Talking about the fourth option i.e. ${{C}_{16}}{{H}_{33}}N{{(C{{H}_{3}})}_{3}}Cl$ , it is named as cetyl trimethyl ammonium chloride, and it is a cationic surfactant, as it contains a nitrogen atom having positive charge on it.

- Thus, in the last we can conclude that the cationic surfactant is ${{C}_{16}}{{H}_{33}}N{{(C{{H}_{3}})}_{3}}Cl$

The correct option is (D).

Note: Don’t get confused between the cationic, and anionic surfactants. We have already discussed the cationic surfactants. Anionic surfactants are those having hydrophobic part, or we can say lipophilic part i.e. water hating end, and an anion attached to it.