How does distillation increase the concentration of ethanol after fermentation?

Distillation increases the concentration of ethanol in a fermented mixture by exploiting the difference in boiling points between ethyl alcohol (approximately 78.5 °C) and water (100 °C).1

Because the vapor above a liquid mixture contains a higher proportion of the more volatile component—the substance with the lower boiling point—heating the mixture to a temperature above 78.5 °C but below 100 °C causes the ethanol to vaporize more readily than the water. When this vapor is captured and cooled in a condenser, the resulting liquid (distillate) has a significantly higher concentration of ethanol than the original fermented mixture.123

For higher purity, a process called rectification or fractional distillation is used. By employing a column that facilitates a multistage operation, the mixture undergoes repeated cycles of vaporization and condensation. This allows the more volatile ethanol to concentrate at the top of the column, effectively separating it from water and other unwanted compounds.42