Ethyl alcohol (100%)
Ethyl alcohol (95%), the azeotrope
Butyl alcohol Amyl alcohol Furfural
Chemicals of different volatility such as those in the table above have different vapour pressures, the most volatile with the lowest boiling point having the highest vapour pressure at any particular temperature. A liquid boils when its temperature is raised to the point where its vapour pressure equals atmospheric pressure. When a mixture of liquids of different boiling points is heated the vapour contains all the compounds which are in the liquid but is slightly richer in the more volatile components. This will be found by condensing the vapour to liquid and analysing it. It is the basis of all distillations — the vapour is richer than the liquid in volatile constituents.
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