Question

The mixture that forma maximum boiling azeotrope is :

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

Answer 1

The Correct Option is A

In chemistry, an azeotrope is a mixture of two or more liquids whose proportions cannot be altered by simple distillation. This is because the composition of the vapor phase is the same as that of the liquid phase. Thus, azeotropes boil at a constant temperature and remain unaltered upon boiling.

There are two types of azeotropes:

1. Minimum Boiling Azeotrope: Boils at a lower temperature than either of its components.
2. Maximum Boiling Azeotrope: Boils at a higher temperature than either of its components.

The question asks which mixture forms a maximum boiling azeotrope. Let's analyze the given options:

• Water + Nitric acid: This mixture forms a maximum boiling azeotrope at approximately 68% nitric acid by mass and boils at about 120.5°C. It is a stable mixture that does not separate under simple distillation conditions, making it a maximum boiling azeotrope.
• Ethanol + Water: This mixture forms a minimum boiling azeotrope. It boils at 78.1°C, which is lower than the boiling points of either ethanol or water.
• Acetone + Carbon disulphide: This pair does not form any azeotrope.
• Heptane + Octane: This mixture does not form an azeotrope as both components have similar boiling points and exhibit almost ideal behavior.

Based on the above analysis, the correct answer is:

• Water + Nitric acid is the mixture that forms a maximum boiling azeotrope.

This conclusion is based on specific boiling point behavior, where the mixture of water and nitric acid demonstrates characteristics of a maximum boiling azeotrope by having a higher boiling point compared to its individual components.