Question

An azeotropic mixture of HCl and water has:
A. 84% of HCl
B. 22.2% HCl
C. 63% of HCl
D. 20.2% HCl

Answer 1

Azeotropic mixtures are considered as those mixtures which boils at constant temperature and the composition of the mixture is same at the liquid phase as well as vapour phase.

Complete step by step answer:
The azeotropic mixture is defined as the mixture of substances which contains the same vapour concentration and fluid phases. The azeotropic mixture contains two or more liquids. The substance in the azeotropic mixture has the same boiling point and vapours of the mixture also have the same composition as the liquid.
The Azeotropic mixture forms non-ideal solution which means they does not follows Rault’s law.
The azeotropic mixture is differentiated into many types like negative azeotropes, positive azeotropes, heterogeneous or homogeneous azeotropes.
The azeotropic mixture of HCl and water is the example of negative azeotrope. The negative azeotrope is defined as those azeotropes where the mixture has less boiling point. The boiling point of water is 100 degree Celsius while for hydrochloric acid is -8 degree Celsius but their azeotropic mixture boils at 78 degree Celsius which indicates that the boiling point is greater than its constituents boiling point. The negative azeotropic mixture of HCl and water contains 20.2% HCl and 78 % water.
Thus, an azeotropic mixture of HCl and water has 20.2% HCl.
Therefore, the correct option is D.

Note:
Don’t get confused by the boiling point of individual substances as in an azeotropic mixture the boiling point of both the substances is considered which can be higher than the constituents or lower than the constituents depending on the type of azeotrope.