Evaporation

What is Evaporation ?

Evaporation is the process by which water is converted from its liquid form to its vapor form and thus transferred from land and water masses to the atmosphere. Evaporation will be understood as the physical process of concentrating solutions by removing part of the water from them by vaporization

 

This is factors influencing the rate of evaporation

1. Concentration of the substance evaporating in the air. When the air already has a high concentration of the substance evaporating, then the given substance will evaporate more slowly.
2. Concentration of other substances in the air. When the air is already saturated with other substances, it can have a lower capacity for the substance evaporating.
3. Concentration of other substances in the liquid (impurities). When the liquid contains other substances, it will have a lower capacity for evaporation.
4. Flow rate of air. This is in part related to the concentration points above. If fresh air is moving over the substance all the time, then the concentration of the substance in the air is less likely to go up with time, thus encouraging faster evaporation. This is the result of then boundary layers at the evaporation surface decreasing with flow velocity, decreasing the diffusion distance in the stagnant layer.
5. Inter-molecular forces. The stronger the forces keeping the molecules together in the liquid state, the more energy one must get to escape. This is characterized by the entalphy of vaporation
6. Pressure. Evaporation happens faster if there is less exertion on the surface keeping the molecules from launching themselves.
7. Surface area. A substance that has a larger surface area will evaporate faster, as there are more surface molecules that are able to escape. Temperature of the substance If the substance is hotter, then its molecules have a higher average kinetic energy, and evaporation will be faster.
8. Density. The higher the density the slower a liquid evaporates. 

Examples of evaporation :
Evaporation water from the oceans accounts for 80% of the water delivered as precipitation, with the balance occurring on land, inland waters and plant surfaces. The enthalpy of vaporization, also known as the heat of vaporization or heat of evaporation, is the energy required to transform a given quantity of a substance into a gas at a given pressure (often atmospheric pressure).  the process by which water is converted from its liquid form to its vapor form and thus transferred from land and water masses to the atmosphere.