Evaporation

Definition - What does Evaporation mean?

Evaporation is an endothermic process that changes a liquid into a gaseous state before reaching the boiling point of the liquid. The rate of evaporation is linked with many factors such as the surface area, temperature of the liquid and the temperature of the surrounding air. A system’s evaporation rate slows down once the vapor pressure achieves equilibrium.

Controlling the evaporation rate is very important in industries where the products are thermo-sensitive.

Corrosionpedia explains Evaporation

Unlike boiling, evaporation does not occur at a fixed temperature. Factors that can affect the evaporation rate include:

  • Temperature
  • Humidity
  • Surface area
  • Air movement (e.g., wind)

Temperature and surface area are directly proportional to the evaporation rate. Higher temperatures give the liquid molecules more kinetic energy, which helps to overcome intermolecular forces. As evaporation only occurs at the surface of a liquid, more surface area increases the evaporation rate. Additionally, evaporation requires heat and dry air. Thus, humidity decreases its rate.

Apart from the factors explained above, the evaporation rate also depends on the heat supplied and the strength of intermolecular forces in a liquid. Therefore, liquids containing hydrogen bonds have lower evaporation rates than those with Van der Waal's intermolecular forces.

Evaporators are used to produce pharmaceutical products, coffee extracts, fruit juices, and for treating oil and water.

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