Question

On which factors does the vapour pressure of a liquid depend?

Answer 1

The vapour pressure of a liquid depends upon the following two factors.

1. Nature of liquid: Liquids with high intermolecular forces have lower vapour pressures at a given temperature than those with weaker intermolecular forces. A faster rate of evaporation results from more molecules being able to escape when intermolecular interactions are weak. As a result, there is a high vapour pressure. For example, because alcohol has weaker intermolecular interactions than water, its vapour pressure is always higher at a given temperature.
2. Temperature: A liquid’s vapour pressure increases as its temperature increases. This is due to the fact that when the temperature rises, the energy of the liquid molecules increases, allowing a greater percentage of molecules to escape into the vapour phase. As a result, the rate of evaporation rises, raising the liquid’s vapour pressure in the process.