Explain how to find the size of molecule of a liquid using oleic acid.
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let us now discuss a technique for determining approximately the molecular size of oleic acid. Oleic acid is a soapy liquid having a sufficiently large molecular size of the order of 10-9 m. Let us dissolve 1 cm3 of oleic acid in 20 cm3 of alcohol. Again, dissolve 1 cm3 of this solution in 20 cm3 of alcohol so that the concentration of 1 oleic acid in alcohol is 1/(20 × 20) cm3 . A few drops of the solution so prepared are put on to the surface of water. The film so formed is stretched so that its thickness is just equal to molecular size. When the alcohol evaporates, a film of oleic acid is left. The area 'A' of the film is measured by using a tracing paper and a graph sheet.
If 'n' drops of solution were put on water, then
Volume of n drops of solution = n × ν cm3 where ν cm3 is the volume of each drop.
If the film has one molecular thickness, then the thickness of oleic acid film will directly give the approximate size or diameter of a molecule of oleic acid. The value comes out to be of the order of 10-9m.
hope it helps
If 'n' drops of solution were put on water, then
Volume of n drops of solution = n × ν cm3 where ν cm3 is the volume of each drop.
If the film has one molecular thickness, then the thickness of oleic acid film will directly give the approximate size or diameter of a molecule of oleic acid. The value comes out to be of the order of 10-9m.
hope it helps
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