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PCAT Chemical Processes – Fatty Acids

  • by Sam
  • Oct 25, 2017
  • PCAT Question of the Day

Which of the following correctly describes the behavior of fatty acids placed in aqueous solution?


A) They will spontaneously form micelles, with the hydrophobic heads clumping together and the hydrophobic tails pointing outwards.

B) They will dissolve in the solution with adequate stirring.

C) It is impossible to get fatty acids to interact with water as they will form an oily layer on top of the water.

D) They will spontaneously form micelles, with the hydrophobic tails clumping in the center of the micelle and the hydrophilic heads pointing outwards.


Fatty acids are amphipathic molecules, with a charged hydrophilic head and a long hydrocarbon tail that is hydrophobic. To minimize the contact area between the water and the hydrophobic tails, the fatty acids will spontaneously form micelles, small spherical structures with the fatty acid tails clumped in the middle. Thus, (D) is the right answer.

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