Question

At CMC, the surfactant molecules:

• A. Decompose
• B. Become completely soluble
• C. Associate
• D. Dissociate

Answer 1

The correct option is C

Associate

Explanation for correct option

(C) Associate

CMC

• Whenever surfactants are used, CMC (Critical micelles concentration) is important.
• The primary use of surfactants is to clean, grease, or remove dirt from clothing.
• A tensiometer is used to measure the surface tension of a concentration series in order to calculate the CMC.

Associate

• The CMC is the concentration of a surfactant in a bulk phase above which surfactant molecule aggregates, also known as micelles, begin to form.
• There is a condition that only occurs at a specific temperature known as the kraft temperature.
• Thus, the surfactant molecules associate and form micelles at CMC, or critical micelle concentration, and kraft temperature.
• These micelles aid in cleaning clothing of grime, oil, and other contaminants.

Explanation for incorrect options

• At CMC, surfactant molecules associate and form micelles.
• Hence, all the other options (A), (B) and (D) are incorrect.

Therefore the correct option is (C) Associate.