Question

Choose the correct statement with respect to the vapor 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

Hint: Molecules of the liquid can be converted into vapor by increasing the temperature of the liquid. These vapor molecules possess kinetic energy that increases when the temperature increases.

Complete step by step solution:
Liquids are those in which the molecules are not so close to each other, and these on high temperature convert into vapor form in which the molecules move far from each other. So, these molecules exert pressure on the container or wall when the temperature increases. Hence we can say that vapor pressure of the liquid or vapor pressure of the solution is known as the pressure exerted by the vapor when the liquid and vapor are in equilibrium.
But this increase in vapor pressure of the liquid is not linear with the increase in vapor pressure.
This is due to the fact that molecules of the liquid possess kinetic energy and when the temperature increases the kinetic energy of the liquid increases and they start to escape the surface and exert pressure on the container. As the molecules collide with each other, their kinetic energy is not the same, hence the vapor pressure is not linear.

Hence, the correct answer is an option (B) Increases non-linearly with increasing temperature.

Note: There is another factor that decides the vapor pressure of the liquid i.e., nature of the liquid, the liquid that has weak van der Waal forces will have higher vapor pressure than the liquid that has strong van der Waal forces.