Question

The formation of micelles takes place only above:
A.) Critical temperature
B.) Kraft temperature
C.) Inversion temperature
D.) Absolute temperature

Answer 1

Hint: Micelles are formed by the self assemblance of amphiphilic molecules. The formation of micelles takes place only above a certain temperature and above a particular concentration.

Complete step by step answer:
Micelles are the aggregate of the surfactant molecules which are dispersed in a liquid colloid. They are formed by the self assemblance of amphiphilic molecules. The structures contain hydrophilic/polar region (head) and hydrophobic/nonpolar region (tail). Micelle in an aqueous solution forms an aggregate with the hydrophilic head regions in contact with surrounding solvent, sequestering the hydrophobic single-tail regions in the micelle centre. In other words, the polar region faces the outside surface of the micelle and the nonpolar region forms the core. Micelles can deliver both hydrophilic and hydrophobic agents.
Micelles are generally spherical in shape ranging in size from 2 to 20 nm depending on the composition. Other phases, including shapes such as ellipsoids, cylinders, and bilayers, are also possible. The shape and size of a micelle are a function of the molecular geometry of its surfactant molecules and solution conditions such as surfactant concentration, temperature, pH, and ionic strength. The most common methods for micelle preparation include oil in water emulsion, solvent evaporation, solid dispersion, and dialysis methods.
The formation of micelles takes place only above a particular temperature called Kraft temperature (\[{T_k}\]​) and above a particular concentration called critical micelle concentration (CMC).

Hence, the correct answer is (B) Kraft temperature.

Note: Remember that only associated colloids can form micelles. Associated colloids are those colloids which behave as normal strong electrolytes at low concentrations but exhibit colloidal properties at higher concentrations due to the formation of aggregated particles (micelles).