Water and alcohol are easily separated by distillation because of their
A. different boiling points
B. different densities
C. different melting points
D. different methods
The correct answer and explanation is:
The correct answer is A. different boiling points.
Explanation:
Distillation is a separation technique that relies on differences in boiling points of substances in a mixture. When a mixture of two or more liquids is heated, the liquid with the lower boiling point vaporizes first. The vapor is then collected and condensed back into liquid form, effectively separating it from the other components.
Water and alcohol (such as ethanol) form a mixture called a solution. Alcohol has a lower boiling point than water—ethanol boils at about 78.4°C while water boils at 100°C at standard atmospheric pressure. Because of this difference, when the mixture is heated, the alcohol vaporizes before the water. The vapor can be captured, cooled, and collected as a separate liquid, resulting in the separation of alcohol from water.
Other options are incorrect for the following reasons:
- Different densities: Density differences alone are not enough to separate two miscible liquids like water and alcohol because they form a homogeneous mixture and do not separate into layers easily.
- Different melting points: Melting points refer to the solid-to-liquid phase change and are not relevant for separating liquids in a mixture.
- Different methods: This is vague and does not specify a reason related to the physical properties that allow separation by distillation.
In summary, distillation works for water and alcohol because their boiling points differ significantly. This property allows selective vaporization and collection, making distillation a common method for separating mixtures of liquids like water and alcohol.