Question

Among the following, the surfactant that will form micelles in an aqueous solution at the lowest molar concentration at the ambient condition is:

• A. $C{H}_3\left(C{H}_2{)}_{15}{N}^{+}\right(C{H}_3{)}_{3}B{r}^{-}$
• B. $C{H}_3(C{H}_2{)}_{11}OS{O}_3^{-}N{a}^{+}$
• C. $C{H}_3(C{H}_2{)}_{6}CO{O}^{-}N{a}^{+}$
• D. $C{H}_3\left(C{H}_2{)}_{11}{N}^{+}\right(C{H}_3{)}_{3}B{r}^{-}$

Answer 1

The correct option is A $C{H}_3\left(C{H}_2{)}_{15}{N}^{+}\right(C{H}_3{)}_{3}B{r}^{-}$

At the critical micelle concentration, the anions are pulled into the bulk of the solution and aggregate to form a spherical shape.
Longer the hydrophobic part of the molecule, the micelle formation will be easier. Since, the hydrophobic part is longer in $C{H}_3\left(C{H}_2{)}_{15}{N}^{+}\right(C{H}_3{)}_{3}B{r}^{-}$, it forms micelles in an aqueous solution at the lowest molar concentration at the ambient condition.