Question

On the basis of information given below mark the correct option.

Information:On adding acetone to methanol some of the hydrogen bonds between methanol molecules break.
A. At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show positive deviation from Raoult's law
B. At specific composition methanol-acetone mixture will form maximum boiling azeotrope and will show positive deviation from Raoult's law
C. At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show negative deviation from Raoult's law
D. At specific composition methanol-acetone mixture will form maximum boiling azeotrope and will show negative deviation from Raoult's law

Answer 1

The correct option is A, where a specific composition of methanol-acetone mixture forms a minimum boiling azeotrope with a positive deviation from Raoult's law, due to the disruption of hydrogen bonds and weaker A-B interactions.

Step-by-step explanation:

At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show positive deviation from Raoult's law. This is because the addition of acetone disrupts the extensive hydrogen bonding network within the methanol, leading to weaker intermolecular forces overall. As a result, the vapor pressure of the mixture becomes higher than what Raoult's law would predict for an ideal solution.

This scenario where the A-B interactions (acetone-methanol) are weaker than the A-A (methanol-methanol) and B-B (acetone-acetone) interactions in the pure components corresponds to a positive deviation from Raoult's law. The formation of a minimum boiling azeotrope is consistent with such a deviation since the addition of acetone lowers the overall boiling point of the mixture compared to that of pure methanol. Thus, the correct option is A.