The method used in separating a mixture of two miscible liquids having sufficient difference in their boiling points is :
- A.Filtration
- B.Solvent Extraction
- C.Centrifugation
- D.Simple Distillation
Correct answer
Explanation
The correct answer is D, Simple Distillation. Two liquids that mix completely but boil at clearly different temperatures can be separated by heating the mixture and condensing the vapour of the lower-boiling liquid first.
In simple distillation the mixture is heated in a flask; the liquid with the lower boiling point turns into vapour first, passes through a condenser and is collected as a pure liquid, while the other stays behind. It works well when the boiling points differ by more than about 25 °C, as with acetone (56 °C) and water (100 °C). When the difference is smaller, fractional distillation with a fractionating column is used, as for separating the gases of air or the fractions of petroleum.
A is wrong: filtration separates an insoluble solid from a liquid, not two liquids that have mixed.
B is wrong: solvent extraction uses a second solvent to pull out a solute and works on differences in solubility, not boiling point.
C is wrong: centrifugation spins a mixture to separate suspended particles of different density, such as cream from milk.
Exam tip: boiling point gap over 25 °C: simple distillation; gap under 25 °C: fractional distillation.
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