Question

In which case can components be separated using a separating funnel?

• A. Mixture of acetone and water
• B. Mixture of oil and water
• C. Different gases in air
• D. None of the above

Hint:

A separating funnel works only on two liquids that do not mix and form separate layers.

Answer 1

The Correct Option is B

Step 1: A separating funnel is a pear shaped glass vessel with a stopcock at the bottom, it is used specifically to separate two liquids that do not mix with each other, that is, two immiscible liquids that settle into distinct layers based on their different densities.
Step 2: Oil and water do not dissolve in one another, oil is nonpolar and water is polar, so when shaken and left to stand they separate into two clear layers, with the denser water layer sitting at the bottom and the lighter oil layer floating on top inside the separating funnel. Opening the stopcock lets the bottom water layer drain out first, and then the stopcock is closed, leaving the oil layer behind. This is a textbook demonstration of separating funnel use.
Step 3: Acetone and water are completely miscible with each other, they mix to form a single homogeneous solution with no visible boundary, so a separating funnel, which relies on two separate layers, cannot separate them at all, this mixture instead needs distillation. Different gases present in air, such as nitrogen, oxygen and argon, are separated industrially by fractional distillation of liquefied air, not by any liquid liquid separating funnel method, since air is a gaseous mixture to begin with. Since option B actually works with a separating funnel, option D, none of the above, is not correct either.
Step 4: Therefore oil and water, option B, is the mixture that a separating funnel can correctly separate.