Why is a dilute solution of oleic acid used instead of pure oleic acid?

Hello!

Dilute solution of oleic acid in pentane is used instead of pure oleic acid to form a monolayer when pentane evaporates.

This substance is used in an experiment to determine the Avogrado Number. In this experiment, a dilute solution of oleic acid in pentane is placed over a known area of water. When pentane evaporates, a monolayer of oleic acid over water is formed and measuring the area of this monolayer will allow you to determine the Avogadro Number.

If pure oleic acid were used, the acid would mix with the water and the monolayer would not form.

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