What method can be used to to completely separate a solution containing alcohol and water?

Fractional Distillation

Explanation:

Fractional distillation is a type of separating technique used to separate constituents of a mixture (miscible) with varying boiling points. In fractional distillation, heat is applied to the mixture and the constituent with the least boiling point vaporizes out first, then the one with the next boiling point follows (the jars used to obtain the constituents will be changed at different boiling points) and the one with the highest boiling point is obtained last. Alcohol/ethanol has a boiling point  of 78°C while water has a boiling point of 100°C hence after exposure to heat, ethanol evaporates out first (and then cooled outside the distilling flask; in a condenser, so it can be converted back to liquid). Since we have just two constituents in this mixture, only water will be left in the distilling flask at about 85°C.