Concept:
Binary liquid mixtures are categorized by their vapor pressure behavior relative to Raoult's law, which depends on the relative magnitudes of adhesive (\(\text{A-B}\)) versus cohesive (\(\text{A-A}\) and \(\text{B-B}\)) intermolecular interactions. Step 1: Identifying the Ideal Solution:
An ideal solution forms when intermolecular interactions between unlike components are nearly identical to those between like molecules (\(\text{A-B} \approx \text{A-A} \approx \text{B-B}\)), resulting in \(\Delta H_\text{mix} = 0\) and \(\Delta V_\text{mix} = 0\).
Bromoethane (\(\text{C}_2\text{H}_5\text{Br}\)) and chloroethane (\(\text{C}_2\text{H}_5\text{Cl}\)) have similar molecular sizes and polarities, forming a nearly ideal solution.
Therefore, (A) corresponds to (II). Step 2: Identifying Positive Deviation from Raoult's Law:
Positive deviation occurs when \(\text{A-B}\) attractive interactions are weaker than \(\text{A-A}\) or \(\text{B-B}\) interactions, increasing the tendency of molecules to escape into the vapor phase.
Pure ethanol molecules are associated via hydrogen bonding. When acetone is added, its molecules sit between ethanol molecules and partially break their hydrogen bonds, increasing total vapor pressure.
Therefore, (B) corresponds to (III). Step 3: Identifying Negative Deviation from Raoult's Law:
Negative deviation occurs when \(\text{A-B}\) interactions are stronger than \(\text{A-A}\) and \(\text{B-B}\) interactions, lowering total vapor pressure.
In a mixture of phenol and aniline, intermolecular hydrogen bonding between the phenolic hydrogen and the lone pair of the aniline nitrogen is stronger than the individual interactions in pure liquids.
Therefore, (C) corresponds to (IV). Step 4: Identifying the Azeotropic Mixture:
An azeotrope is a liquid mixture of fixed composition that boils at a constant temperature without any change in liquid and vapor composition.
A mixture containing \(95\%\) ethanol and \(5\%\) water by volume forms a minimum boiling azeotrope that cannot be separated by fractional distillation.
Therefore, (D) corresponds to (I). Final Answer:
The matching combination is (A)-(II), (B)-(III), (C)-(IV), (D)-(I), which corresponds to option (B).
