Question

Consider the following surfactants.
$C{H}_3(C{H}_2{)}_{8}COONa$: Surfactant $\text{I}$
$C{H}_3(C{H}_2{)}_{10}COONa$: Surfactant $\text{II}$
$C{H}_3(C{H}_2{)}_{12}COONa$: Surfactant $\text{III}$
Select the correct statements(s).

• A. If critical micelle concentration $\text{(C.M.C.)}$ of surfactant $\text{I, II}$ and $\text{III}$ are $x,y$ and $z$ respectively then $z>y>x$
• B. $-\stackrel{\stackrel{O}{||}}{C}-O^{-}$ part of each surfactant is water loving and is called as head
• C. Alkyl group of each surfactant is water repelling and is called as tail
• D. If critical micelle concentration of surfactant $\text{I, II}$ and $\text{III}$ are $x,y$ and $z$ respectively then $x>y>z$

Answer 1

Answer: (A), (B), (C)

Alkyl group of each surfactant is water repelling and is called as tail

Surfactants are usually organic compounds that are amphiphilic, meaning they contain both hydrophobic groups (their tails) and hydrophilic groups (their heads). Therefore, a surfactant contains both a water-insoluble (or oil-soluble) component and a water-soluble component.
The formation of micelles takes place only above a particular concentration called critical micelle concentration (CMC)
Longer the hydrophobic tail, lesser is the $\text{(C.M.C.)}$ therefore $\text{C.M.C.}$ order will be $z>y>x$.