Main Difference – Evaporation vs. Condensation
Evaporation and condensation both refer to a phase change between vapor and liquid phases. The main difference between evaporation and condensation is that evaporation involves a phase change from liquid phase to vapor phase at temperatures below the boiling temperature of the liquid, whereas condensation involves a phase change from vapor to liquid phase.
What is Evaporation
Evaporation is a process whereby molecules in a liquid become a vapor at temperatures below the liquid’s boiling point. This happens because molecules in a liquid have a large range of kinetic energies, and some of the molecules will have enough kinetic energy to overcome attractive forces which keep them bound in the liquid form.
If the liquid is in a closed space, then some of the escaped molecules can come back to contact with the liquid surface and rejoin the molecules in the liquid. Eventually, an equilibrium gets established where the rate of evaporation becomes equal to the rate at which molecules are rejoining the liquid. At this stage, the air is said to have achieved the maximum saturation level.
What is Condensation
During condensation, materials in the vapor phase undergo a phase change to become liquid. This happens when air reaches the maximum saturation level for a gas. The maximum saturation level of water molecules in the air can be reduced by decreasing he temperature or by increasing the pressure. As we discussed earlier, some of the “escaped” vapor molecules near the surface of a liquid can condense and become liquid again. Condensation can be also seen around bottles carrying cold drinks, because due to the lower temperature around the bottle, the amount of water vapor that can be in the air before reaching saturation is smaller. On rainy days, the air may become saturated with water vapor and cause water to condense on the insides of windows, as well.
Condensation happens when the temperature of the air is lowered. This reduces the amount of water vapor that can exist in air, so the water molecules join together to form liquid droplets.
When water is boiled in a home, the outside air temperature is not high enough to maintain the steam in gas phase. So the water molecules come together to form microscopic droplets. This is also a process of condensation. The water cycle is driven by the evaporation of water from bodies of water, which gets carried up by the wind, and eventually condenses in the clouds and rains down.
Condensing water droplets above a cup of hot coffee (or tea) disperse light and so can be detected when light shines on them.
Difference Between Evaporation and Condensation
Phase Change
Evaporation involves a phase change from liquid to vapor.
Condensation is the reverse of evaporation, where the phase changes from vapor to liquid.
Terminology
Evaporation only refers to phase change from liquid to vaopor below the boiling point. If this phase change occurs at the boiling point, the process is referred to as boiling.
Condensation refers to phase change from vapor to liquid regardless of the temperaure.
Image Courtesy
(Untitled) by User:Acdx (Own work) [CC BY-SA 3.0], via Wikimedia Commons
“Water condenses into visible droplets after evaporating from a cup of hot tea” by Jarombouts (Own work) [CC BY-SA 3.0], via Wikimedia Commons
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