Increasing pressure typically decreases the rate of evaporation, and as the temperature of water increases, the rate of evaporation generally increases. Let's explore these two aspects:
Effect of Pressure on Rate of Evaporation:Increasing Pressure Decreases Evaporation: In general, higher pressure tends to inhibit the process of evaporation. This is because an increase in pressure over the liquid surface makes it more difficult for molecules at the liquid's surface to escape into the vapor phase. Essentially, higher pressure "pushes" the vapor molecules back into the liquid, making it harder for them to evaporate. Conversely, lower pressure allows for easier evaporation because there is less resistance to the molecules leaving the liquid surface.
Effect of Temperature on Rate of Evaporation:Increasing Temperature Increases Evaporation: Higher temperatures provide more thermal energy to the liquid molecules, increasing their kinetic energy. As a result, a larger fraction of molecules at the liquid surface will have enough energy to overcome the intermolecular forces holding them in the liquid phase. This leads to an increase in the rate of evaporation as temperature rises. Essentially, higher temperature increases the likelihood that molecules will transition from the liquid to the vapor phase.
So, in summary:
Increasing pressure tends to decrease the rate of evaporation.
Increasing temperature tends to increase the rate of evaporation.
These principles are often used in various applications and can be seen in everyday life. For example, cooking at higher temperatures results in faster evaporation of water from a boiling pot, while lower pressure conditions at high altitudes can cause water to boil at a lower temperature and evaporate more easily.
Temperature of liquid does not change during evaporation because the heat taken by the water from the surrounding is used to convert the state of water from liquid to gas by increasing kinetic energy among the molecules and this kinetic energy increases the intermolecular space. The potential evaporation rate increases with temperature, vapor pressure difference between the surface and the atmosphere, and wind velocity.Vapor pressure is a measure of the pressure exerted by a gas above a liquid in a sealed container. Strong intermolecular forces produce a lower rate of evaporation and a lower vapor pressure. Weak intermolecular forces produce a higher rate of evaporation and a higher vapor pressure. The greater the temperature of the liquid and its surroundings, the faster the rate of evaporation. Surface area occupied by the liquid: Since evaporation is a surface phenomenon, the greater the surface area occupied by the liquid, the quicker it undergoes evaporation.Greater air pressure means that the water molecules will exert more energy to evaporate. Less air pressure means small amount of force for water molecules to leave their companion molecules and rise to the clouds. Evaporation decreases as the atmospheric pressure increases, or example when a high pressure system is present. Conversely, evaporation increases as atmospheric pressure decreases, such as with increasing elevation. As the temperature of a liquid increases, the vapor pressure of the liquid increases until it equals the external pressure, or the atmospheric pressure in the case of an open container. As the temperature of a liquid increases, the vapor pressure of the liquid increases until it equals the external pressure, or the atmospheric pressure in the case of an open container. For evaporation at the same temperature but higher pressure, the evaporation heat does not increase, but is effectively integrated with higher work done on gas. Last but not least, enthalpy is state function at constant pressure. The pressure of the steam used for evaporation greatly affects the rate of evaporation; the higher the steam pressure (hence higher the temperature) the more water can be evaporated over a given length of time. Although water can evaporate at low temperatures, the rate of evaporation increases as the temperature increases. This makes sense because at higher temperatures, more molecules are moving faster; therefore, it is more likely for a molecule to have enough energy to break away from the liquid to become a gas. The potential evaporation rate increases with temperature, vapor pressure difference between the surface and the atmosphere, and wind velocity. Actually, rate of evaporation of a liquid decreases as the temperature decreases. As intermolecular force increase rate of evaporation decreases. This happens because intermolecular force makes it less likely for the molecules on the surface to escape from liquid and become vapour gas. Air pressure also affects evaporation. If air pressure is high on the surface of a body of water, then the water will not evaporate easily. The pressure pushing down on the water makes it difficult for water to escape into the atmosphere as vapor.