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Associated Colloids and Micelles
Concepts tested here
- Cationic surfactants form micelles
All Questions
2005 AIPMT 1 question
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Which one of the following forms micelles in aqueous solution above certain concentration -Micelles are aggregates formed by surfactant molecules, which have a long non-polar hydrocarbon tail and a polar or ionic head.
Above a certain concentration, called the critical micelle concentration (CMC), and above the Kraft temperature, these molecules associate so that the hydrophobic tails point inwards and the ionic heads face the water.
Dodecyl trimethyl ammonium chloride, $CH_3(CH_2)_{11}N^+(CH_3)_3Cl^-$, has a long $C_{12}$ hydrocarbon chain and an ionic head; it is a cationic detergent.
So it forms micelles in aqueous solution above a certain concentration.
Glucose and urea are small, water-soluble molecules without a long hydrophobic chain, and pyridinium chloride is a simple salt; none of them forms micelles.
So the answer is dodecyl trimethyl ammonium chloride.