Question

My teacher said that vapour pressure is independent of the surface area and volume of a liquid. But I think it should be dependent, because surface area is directly proportional to the evaporation rate and if I increase surface area of a liquid then more liquid will be evaporated and more vapours will form and hence vapour pressure will be increased. And similar approach for volume of liquid also. Where am I wrong?

Answer 1

Vapor pressure is influenced by temperature, but it is independent of the surface area and volume of the liquid.

Step-by-step explanation:

Vapor pressure is influenced by temperature. As the temperature increases, more molecules are released from the surface of the liquid. This increases movement above the liquid surface, increasing the pressure in the vapor stage.

However, vapor pressure is independent of the surface area and volume of the liquid. When the temperature is held constant, the rate at which molecules escape from the liquid into the vapor phase depends only on the surface area of the liquid phase. Increasing surface area will increase the rate of evaporation, but it will also increase the rate of condensation.

Eventually, a dynamic equilibrium is reached, where the rate of evaporation equals the rate of condensation, and the vapor pressure remains constant.