Which method will you use to separate methyl alcohol from acetone?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Fractional distillation
Fractional distillation separates two miscible liquids whose boiling points differ by less than about 25 K. The mixture is heated and its vapour rises through a fractionating column; the liquid with the lower boiling point distils over first.
Acetone boils at about 56°C and methyl alcohol (methanol) at about 65°C. They mix completely and their boiling points are only about 9°C apart, so fractional distillation is the method; acetone comes over first.
Why the other options are incorrect
Option (1) Crystallisation — Incorrect. It recovers a pure solid from its solution, such as sugar or copper sulphate.
Option (2) Evaporation — Incorrect. It drives off a liquid to recover a dissolved solid, so both liquids here would be lost.
Option (3) Filtration — Incorrect. It separates an insoluble solid from a liquid, not two liquids that mix.