Question

Which is the most effective method of separating mixtures of miscible volatile liquids?
A.Fractional Distillation
B.Simple distillation
C.Chromatography
D.Filtration

Answer 1

Hint: To solve this question, we need to first understand the principles on which these processes mentioned work. Then we need to relate the mixture given to us to the physical characteristics that can actually differentiate the constituents. Then we need to choose a process which can correctly exploit this differentiating characteristic.

Complete Step-by-Step Answer:
Before we move forward with the solution of the given question, let us first understand some important basic concepts.
Since the mixture consists of volatile liquids, it is going to be very difficult to separate the liquids by using traditional separation techniques like filtration, etc. The options that are provided to us involve slightly advanced techniques. Let us discuss all of them one by one.
A.Fractional distillation: Fractional distillation works on the principle that different miscible liquids have different boiling points. The setup for fractional distillation is such that it involves heating the given liquid mixture at the very bottom. The apparatus is now heated and then a liquid mixture starts to heat. As soon as the temperature of the system becomes equal to the temperature of the constituent liquid with the lowest boiling point, it starts to evaporate. The temperature remains constant till the entire liquid is vaporised. These vapours are collected separately and then cooled to obtain the source liquid. Once the liquid evaporates completely, the temperature starts to rise again. This process goes on till the liquid with highest boiling is vaporised and collected.
B.Simple Distillation: Simple distillation involves the separation of two liquids with different boiling points. The same process is used as in fractional distillation, but the vapours of only one liquid are collected, because the source mixture would be left only with the liquid with the higher boiling point.
C.Chromatography: Chromatography works on the principles of capillarity and adsorption. If a mixture of volatile liquids is left to be absorbed, then there is a high chance that the mixture would evaporate at room temperature itself.
D.Filtration: Filtration would not be of any use in this situation because it involves physical separation using apparatus like filtration paper and sieves. These apparatuses are of no use for separating liquids of any form.

Hence, Option A is the correct option

Note: One of the most important applications of fractional distillation includes the separation of different compounds from crude oil. Crude Oil is the source raw material that is used to obtain products like diesel, petrol, kerosene, paraffin, etc.