Question

Which of the following is property of Azeotropic Mixture:
A) Boil at a different temperature.
B) Mixture of solids.
C) Constant boiling mixture.
D) Gaseous mixture.

Answer 1

Azeotropes are mixtures of two or more liquids at constant boiling point which do not change by simple distillation. Azeotropes are also called constant boiling point mixtures.

Complete answer:
Azeotropes are also called constant boiling point mixtures.
Azeotropic mixture is a mixture of two or more liquids which has a constant boiling point and the composition of constituents is same in liquid and vapour phase.
Thus from definition, we can say that option (A) is incorrect, as it says boils at different temperatures, but we know azeotropic mixture boils at the same temperature.
Option (B) is also incorrect as this mixture is not a mixture of solids rather it is a mixture of liquids.
Even option (D) is incorrect, due to presence of liquid mixture in case of azeotropes not gaseous mixture.
Now, option (C) is correct, as the definition itself says that these mixtures are constant boiling mixtures.

Thus, Correct option is (C) Constant boiling mixture.

Note: There are 2 types of this mixture:
Positive azeotropes: The boiling point of each constituent is more than the boiling point of mixture formed.
Example: 96% ethanol with 4% water. This mixture boils at ${78.2^0}C$ , while for water boiling point is ${100^0}C$ and for ethanol is ${78.4^0}C$.
Negative azeotropes: The boiling point of each constituent is less than the boiling point of mixture formed.
Example: 20% hydrochloric acid and 80% water. This mixture boils at ${110^0}C$ , while water boils at ${100^0}C$ and Hydrochloric acid boils at $- {84^0}C$ .
Mixtures can be of multiple types depending on states of matter: Solid, Liquid, and Gases. Azeotropes are one of the special categories of mixtures, of Liquid liquid mixture, with constant boiling point.