Question

Benzene and chloroform are separated by:
A. Sublimation
B. Filtration
C. Distillation
D. Crystallisation

Answer 1

Hint: To answer this question we should know that the boiling point of benzene is 80℃ & that of chloroform is 61.2 ℃. For separation of benzene and chloroform we should suggest an option that separates the components or substances from a liquid mixture by using selective boiling and condensation.

Complete step-by-step answer:
To answer this question, we should first know about options. If we know something about our options, then we can easily answer a way to separate benzene and chloroform.

Sublimation: About sublimation, we should know that it is the transition of a substance directly from the solid to the gas state, without passing through the liquid state. So, this option is rejected because we have a mixture of benzene and chloroform and that is liquid.

Filtration: We should know that filtration is the process in which solid matter and fluid get separated from a mixture with a filter medium that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as oversize and the fluid that passes through is called the filtrate. So, now we know that filtration is not that process which can separate benzene and chloroform.

Distillation: We should know that distillation is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation. So, let us take the mixture of benzene and chloroform. From theoretical studies we know that the boiling point of benzene is 80℃ & that of chloroform is 61.2 ℃. Then we start to boil a mixture of benzene and chloroform with condenser attached on top of flask to collect vapours and to condense them. Chloroforms with lower boiling point than benzene start to form vapours first. These vapours will be collected and condensed to liquid form. And the same thing will happen for benzene, after 80℃ temperature, benzene starts to form vapours and these are also collected and condensed. So, from this we know that distillation is the process to separate benzene and chloroform.

Crystallisation: We should know that crystallization is a natural process which occurs as materials solidify from a liquid, or as they precipitate out of a liquid or gas. It can be used to purify substances. In the laboratory, we dissolve a substance into an appropriate solvent. Heat and changes in acidity can help the material dissolve. When we reverse these conditions, the materials within the solution precipitate out at different rates. If the conditions are controlled properly, pure crystals of a desired substance can be obtained.

So, from the above discussion we now come to the conclusion. Now, we know the method to separate mixture of benzene and chloroform. Distillation is the process from which we separate them. We used one property and that is the difference in their boiling point. So, option C is correct and we will use distillation to separate benzene and chloroform.

Note: We know about sublimation, but we should also know about some application of sublimation and they are as follows:
Sublimation and erosion cause ablation, a process that wears down glaciers.
Sublimation of iodine may be used to reveal latent fingerprints on paper.
Sublimation is used to purify compounds. It is especially useful for organic compounds.
Because dry ice sublimates so readily, the compound is used to produce fog effects.