The main factors affecting evaporation are as follows:
- Surface area
- Temperature
- Humidity
- Moving air
- Density of liquid
Factors Affecting Evaporation
(i) Surface area
If the surface area of the
evaporating solution is increased, then the amount of liquid that is exposed to
air is larger. More molecules can escape with a wider surface area. For
example, if we spread out clothes to dry it speeds up the process of
evaporation. The larger the exposed surface area, the more molecules can escape
from the liquid. Thus larger the surface area faster is the evaporation.
(ii) Temperature
The water molecules move
rapidly when the water is heated. This makes the molecules escape faster.
Higher temperatures lead to an increase in evaporation as more molecules get
kinetic energy to convert into vapour. For example, boiling water evaporates
faster than normal water.
(iii) Humidity
Humidity means the amount
of vapour present in the air. The air around can only hold a certain amount of
vapour at a certain time and a certain temperature. If the temperature
increases and the airspeed and humidity stay constant, then the rate of
evaporation will increase since warmer air can hold more water vapour than
colder air. Thus, the rate of evaporation decreases with increasing humidity
and increases with vice versa.
(iv) Moving air
Particles of vapour move
away when the speed of air increases. This leads to a decrease in the amount of
water vapour in the atmosphere. For example, we use hand dryers to dry our
hands. Here the air is expelled from the hand dryer which dries our hands.
(v) Boiling point of liquid
Liquids with a lower
boiling point evaporate faster. Mercury hardly evaporates at room temperature
as it has a boiling point of 357 °C.
(vi) Density of liquid
As the density increases,
the rate of evaporation decreases. Liquids with a higher density have a lower
rate of evaporation. For example, honey has a lower rate of evaporation as
compared to water, which has a lower rate of evaporation as compared to
alcohol. This is because honey is denser than water, and water is denser than
alcohol.
Make sure you also check our other amazing Article on : Mechanisms of Heat Transfer