Why is distillation an effective method for separating a mixture of water and acetone?
Distillation is an effective method for separating a mixture of water and acetone because they are miscible liquids with a large difference in their boiling points. Acetone has a lower boiling point of 56 °C, whereas water boils at 100 °C.
This difference is greater than the required minimum of 25 °C for distillation. When the mixture is heated, acetone vaporises first without water forming vapours in significant amounts. These acetone vapours are then cooled in a condenser and collected as a pure liquid, effectively separating it from the water left behind.
Explanation
The textbook states that distillation can separate homogeneous mixtures of miscible liquids if their boiling points differ by at least about 25 °C. Since acetone boils at 56 °C and water at 100 °C, the large difference (44 °C) allows acetone to vaporise first. The vapours are then condensed back into a pure liquid, leaving the water behind in the flask.