Describe a method for measuring the molecular size of oleic acid

Dear student

Your friend has given correct answer and you can refer to it. For further I would like to add the following.

Oleic acid has one hydrophobic and one hydrophilic end. If a small amount of oleic acid is placed on the surface of water, it stands on end with the hydrophilic end towards the water and the hydrophobic end away.

We find the size of one oleic acid molecule by spreading a small amount over the surface of water and measuring the diameter of the circle. The oleic acid spreads itself into a one-molecule thick layer in the shape of a very flat cylinder.

By knowing the volume of the drop of oleic acid and the diameter of the layer, the height of the layer (size of the molecule) can be found.

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