Question

Choose the correct statement with respect to the vapour pressure of a liquid among the following :

• A. Increases linearly with increasing temperature
• B. Increases non-linearly with increasing temperature
• C. Decreases linearly with increasing temperature
• D. Decreases non-linearly with increasing temperature

Answer 1

The Correct Option is B

The vapour pressure of a liquid is a crucial concept in understanding how a liquid behaves under different temperature conditions. Let's analyze the changes in vapour pressure with respect to temperature to answer the question.

Concept Explanation:

Vapour pressure is the pressure exerted by a vapour in equilibrium with its liquid phase at a given temperature. As you increase the temperature of a liquid, its molecules gain kinetic energy, which overcomes intermolecular forces, allowing more molecules to escape into the vapour phase. This results in an increase in vapour pressure.

According to the Clausius-Clapeyron Equation, the relation between vapour pressure and temperature is given by:

\(\frac{d\ln P}{dT} = \frac{\Delta H_{vap}}{RT^2}\)

Where:

• \(P\) is the vapour pressure
• \(T\) is the temperature in Kelvin
• \(\Delta H_{vap}\) is the enthalpy of vaporization
• \(R\) is the universal gas constant

This shows that the natural logarithm of the vapour pressure increases with temperature, but not linearly as it involves the temperature squared.

Conclusion:

From the above explanation, we understand that the vapour pressure of a liquid increases non-linearly with increasing temperature. This is because the changes in pressure are exponential rather than linear due to the temperature dependency in the Clausius-Clapeyron equation.

Correct Answer: Increases non-linearly with increasing temperature.