Which of the following combinations of liquids would be...

Which of the following combinations of liquids would be expected to have a vapor pressure higher than the vapor pressure that would be predicted by Raoult's law?
(A) Ethanol and hexane
(B) Acetone and water
(C) Isopropanol and methanol
(D) Nitric acid and water

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Key Concepts

Raoult's Law

Raoult's Law describes the vapor pressure of an ideal solution, stating that the partial vapor pressure of each component in the solution is equal to the vapor pressure of the pure component multiplied by its mole fraction. This principle assumes that intermolecular interactions in the solution are similar to those in the pure substances, leading to a linear relationship between composition and vapor pressure.

Deviation from Raoult's Law

Real solutions often exhibit deviations from Raoult's Law when the intermolecular forces between unlike molecules differ from those between like molecules. When the interactions between dissimilar molecules are weaker than those in the pure components, the mixture displays a positive deviation, resulting in a higher vapor pressure than predicted. Conversely, stronger interactions lead to negative deviations with a lower vapor pressure.

Intermolecular Forces

Intermolecular forces, such as hydrogen bonding, dipole-dipole interactions, and dispersion forces, determine how molecules interact in both pure substances and mixtures. The balance of these forces is crucial in predicting solution behavior; differences in force strength between similar and dissimilar molecules lead to either ideal or nonideal behavior in liquid mixtures, directly affecting properties such as vapor pressure.

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