Question

The mixture that forms maximum boiling azeotrope is :

• A. Acetone + Carbon disulphide
• B. Heptane + Octane
• C. Water + Nitric acid
• D. Ethanol + Water

Answer 1

The Correct Option is C

Explanation:

An azeotrope is a mixture of two or more liquids whose proportions cannot be changed by simple distillation. This happens because the vapor has the same composition as the liquid mixture. Azeotropes are classified into two types: minimum boiling azeotropes and maximum boiling azeotropes.

Maximum Boiling Azeotropes: Maximum boiling azeotropes have a boiling point that is higher than either of the pure components' boiling points. They are also known as positive azeotropes. This occurs due to strong interactions between the components of the mixture, which leads to a higher boiling point.

In the given options, Water + Nitric acid forms a maximum boiling azeotrope. This mixture boils at a higher temperature than either pure water or pure nitric acid due to strong hydrogen bonding and interactions between water and nitric acid molecules.

Justification for Other Options:

• Acetone + Carbon disulphide: These components do not form a maximum boiling azeotrope. Rather, they can form a minimum boiling azeotrope due to weaker interactions.
• Heptane + Octane: As these are similar hydrocarbons, they do not form an azeotrope because their physical properties are too similar to significantly affect each other's vapor pressures.
• Ethanol + Water: This mixture forms a minimum boiling azeotrope at a certain ethanol concentration.

Thus, the correct answer is Water + Nitric acid.