4th Nov '25

Evaporation

Evaporation is a special example of convection as it involves the movement of . It also involves a change of state, from to .

Evaporation is different to as only a few particles at a time turn into a gas. This happens when the vibrating particles collide with each other, and occasionally one of the particles gains enough energy break the bonds holding it in the liquid. This can only happen at the surface otherwise the energetic particles will hit another particle giving up their energy and staying within the liquid.

Evaporation has a effect on the liquid as the most energetic particles leave the liquid as they turn into a gas. This leaves the liquid cooler as there has been a loss in total amount of heat energy within the liquid.

Condensation is the opposite of evaporation. It will have a effect on the object on on which the liquid condenses. If fact the liquid appears as the gas looses energy to the surface and the particles are unable to overcome the forces that will hold them in a liquid.

The factors that affect the rate of evaporation and condensation are:

The greater the surface area the more particle at the boundary able to turn into a gas. Therefore the greater the surface area the evaporation.

The greater the density of the fluid the more mass each particle has and so more energy required to get it evaporate. Therefore the greater the density of the fluid the evaporation.

The greater the air movement the less previously evaporated particles are close to the liquid surface to get in the way of further evaporation. Therefore the greater the air movement the evaporation.

The greater the temperature the more likely it is that the particles will get enough energy to break free of the liquid. Therefore the greater the temperature the evaporation.