Test: Micelle Formation and CMC - Chemistry MCQ

Sodium stearate ionises to form stearate anion(C₁₇H₃₅COO^–) and sodium cation(Na⁺).

In the micelle formation, the water insoluble tails are directed towards the centre, and the water soluble heads are on the surface in contact with water. All the other options are correct.

The transition of ions to micelle is a reversible process. In the micelle formation, the water insoluble tails are directed towards the centre, and the water soluble heads are on the surface in contact with water.

Micelles behave as colloids only when its concentration is greater than CMC. The CMC is an important characteristic of a surfactant. Before reaching the CMC, the surface tension changes strongly with the concentration of the surfactant. After reaching the CMC, the surface tension remains relatively constant or changes with a lower slope.

The end of the hydrocarbon chain is having a polar group (head) which is hydrophilic in nature and represented by a hollow circle.

About 70 stearate ions aggregate to form a micelle of colloidal size.

The soap micelle is stable due to the negative charge on its polar head. In the micelle formation, the water insoluble tails are directed towards the centre, and the water soluble heads are on the surface in contact with water.

The minimum amount of concentration that is required for the formation of the micelle is termed as Critical Micelle Concentration (CMC). It is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system go to micelles.

The conductivity of micelles is higher than the colloidal solution. And hence they can conduct more electric charges through them.