Explain the formation of micelles with a neat sketch.

Explanation

Mechanism of micelle formation : Let us take the example of soap solution. Soap is sodium or potassium salt of a higher fatty acid and may be represented as `RCOO^(-) Na^(+)` (e.g., sodium strearate `CH_(3)(CH_(2))_(16), COO^(-) Na^(+)`, which is a major component of many bar soaps). When dissolved in water, it dissociates into` RCOO^(-) and Na^(+)` ions. The `RCOO^(-)` ions, however, consist of two parts- a long hydrocarbon chain R (also called non-polar 'tail') which is hydrophobic (water repelling), and a polar group `COO^(-)`(also called polar-ionic 'head'), which is hydrophilic (water loving).
The `RCOO^(-)` ions are, therefore, present on the surface with their `COO^(-)` groups in water and the hydrocarbon chains (R) staying away from it and remain at the surface. But at critical micelle concentration, the `COO^(-)` irons are pulled into the bulk of the solution and are aggregated to form a spherical shape with their hydrocarbon chains pointing towards the centre of the sphere with `COO^(-)` part remaining outward on the surface at the sphere.
The aggregate thus formed is known as 'ionic micelle'. These micelles may contain as many as 100 simple molecules.
Similarly, in case of detergents, e.g., sodium laurylsulphate. `CH_(3) (CH_(2))_(11) SO_(3)^(-)Na^(+)`, the polar group is `-SO_(3)^(-)` along with the long hydrocarbon chain. Hence, the mechanism of micelle formation here also is same as that of soaps.