Which one of the following apparatus is used for separating benzene and water mixture?
- A.Round bottom flask
- B.Conical flask
- C.Separating funnel
- D.Dean and Stark apparatus
Correct answer
Explanation
The correct answer is C, Separating funnel. Benzene and water do not mix, so they form two layers that a separating funnel can draw off one after the other.
Two liquids that are immiscible settle into separate layers according to their density. Benzene, with a density of about 0.88 g/cm³, floats on water. The mixture is poured into a separating funnel and left to stand; then the stopcock is opened to run out the heavier water layer first, and closed just as the benzene layer reaches it. The same method separates oil from water and kerosene from water.
A, a round bottom flask, is used for heating and distillation, and cannot divide two layers by itself.
B, a conical flask, is a container for mixing, titration and storage, with no outlet at the bottom.
D, the Dean and Stark apparatus, collects water removed during a reaction under reflux; it is not the standard tool for separating a simple immiscible pair.
Exam tip: immiscible liquids, separating funnel; miscible liquids with different boiling points, distillation.
Practice Questions
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