Question

As molecules move up a fractional distillation column, they condense and then revaporize. During which of these steps is the concentration of the more volatile compound of the mixture increased? Briefly explain.

Answer 1

During fractional distillation of a mixture, the vapor containing more of the more volatile component and less of the less volatile component begins to move up the distillation column.
When it reaches the part of the column which is cool enough, it condenses. Then it vaporizes again. This time a part of the less voltaile component trickles back to the distillation vessel and the vapor mixture which vaporizes is more rich in the more volatile component.

This process repeats again and again with the concentration of the more volatile compound increasing every time.
So at the end of the column, the less volatile compound is almost eliminated and the almost pure more volatile compound distills over.

So the concentration of the more volatile compound is increased step by step during every condensation and revaporization in the distillation column.





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