Question

Name a technique used to separate: Petrol and water
(A) distillation
(B) separating funnel
(C) sublimation
(D) chromatography

Answer 1

Hint: Petrol is a form of hydrocarbon and water is a polar solvent. Hence, they are immiscible liquids which neither mix nor react with each other. Their respective boiling points are different and can be used as the basis for the separation of petrol from water.

Complete step by step solution:
Distillation is the process of separating the components or substances present in a liquid mixture through selective boiling and condensation. Distillation may result in complete or partial separation based on the difference in boiling points of the substances present in the liquid mixture.
In either case, the process of distillation uses the concept of the relative volatility of the components of the mixture. It has many uses like:
- Separation of fermented products to produce high alcohol content beverages
- Desalination
- Separation of air into its components for industrial use (cryogenic distillation)
- Refining of crude oil
- Oil stabilisation in the petroleum industry
The boiling point of petrol is 483K and that of water in 373K. Since the difference between the boiling point temperatures is high, we can use the method of distillation as explained above to obtain petrol and water from the liquid mixture.

Therefore, the correct answer is option (A).

Note: When the difference between the boiling temperatures of the components of the liquid mixture is less, we use the process of fractional distillation. Fractional distillation is the separation of a liquid mixture into its component parts or fractions. Chemical compounds are separated by heating to a temperature at which more than one fractions of the mixture will vaporise.