What is the equilibrium vapor pressure of a liquid? How does it change with temperature?

Short Answer

Expert verified
The equilibrium vapor pressure of a liquid is the pressure exerted by the vapor in equilibrium with its liquid phase at a certain temperature. As the temperature increases, the equilibrium vapor pressure increases exponentially as per the Clausius-Clapeyron equation.

Step by step solution

01

Understanding Equilibrium Vapor Pressure

Equilibrium vapor pressure is the pressure at which the gas, or vapor, of a substance is in equilibrium with the liquid or solid form of the substance at a certain temperature. In simple terms, it's the pressure created by the vapor particles when the rate of evaporation equals the rate of condensation in a closed system at a given temperature.
02

Relationship between Vapor Pressure and Temperature

The overall behavior of the vapour pressure in function of temperature can be described by the Clausius-Clapeyron equation, which states that the vapor pressure of a liquid at a specific temperature is proportional to the exponential of the ratio of the heat of vaporization and the product of the ideal gas constant and temperature. Mathematically, it can be represented using the formula: \( P = P_0 \times e^{(-ΔH_{vap}/(R \times T))} \). Here, \( P \) is the equilibrium vapor pressure, \( P_0 \) is a reference pressure, \( ΔH_{vap} \) is the molar heat of vaporization, \( R \) is the ideal gas constant, and \( T \) is the absolute temperature.
03

Deriving the Relation

As the temperature increases, the exponential term in the Clausius-Clapeyron equation becomes larger (since temperature \( T \) is in the denominator), making the overall equilibrium vapor pressure \( P \) to increase. Thus, the equilibrium vapor pressure of a liquid increases exponentially with increasing temperature, demonstrating that more molecules can escape from the liquid to the vapor phase when the temperature is raised.

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