The following diagram shows a close-up view of part of the vapor-pressure curves for a solvent (red curve) and a solution of the solvent with a second liquid (green curve). Is the second liquid more volatile or less volatile than the solvent?

Key Concepts

Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature. It reflects the tendency of particles to escape from the liquid phase into the vapor phase. A higher vapor pressure indicates a greater volatility, meaning the substance evaporates more readily.

Volatility

Volatility refers to how easily a substance vaporizes. A volatile liquid has a high vapor pressure at a given temperature, indicating that it can transition to the gas phase quickly. In the context of the question, comparing the vapor pressures of the solvent and the solution helps determine which component is more volatile.

Raoult's Law

Raoult's Law states that the vapor pressure of a solvent in a solution is directly proportional to the mole fraction of the solvent present. When a non-volatile solute is added to a solvent, the vapor pressure of the solvent decreases, indicating that the solution has a lower vapor pressure than the pure solvent, which can help infer the volatility of the second liquid.