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The simplest and most direct explanation is that isotopically heavier molecules have higher boiling points. Regular water (R) boils at 100.0$^o$ C. Heavy water (H) boils at 101.4$^o$ C. A mixture of the two (R + H) can be separated by a distillation column. The heavier molecules require more energy to evaporate, to push away one atmosphere. Any similarity to ...

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As very simple model to find what properties are important in evaporation consider a molecule that when close to the surface moves around in a cell of side $a$ and collides with frequency $f$ into its neighbouring molecules. There is an area $a^2$ through which it can escape the surface and in a second it moves on average a distance $v= 2af$ back and forth ...

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Evaporation depends on molecular velocity not on the energy The simple mistake in your assumption is that evaporation is driven by molecules having enough energy to escape the liquid phase. This is wrong. Evaporation depends on whether the molecule is travelling fast enough to escape the liquid. The molecules in the liquid will have, on average, the same ...

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