Question

How does each of the following affect the rate of evaporation of a liquid in an open dish?
a) Intermolecular forces
b) Temperature
c) Surface area

Answer 1

As we know that the rate of evaporation of a liquid is basically that process which involves the conversion of liquid into its gaseous or vapour state without being heated to its boiling point. Also we know that temperature, surface are and other parameters are directly related to the evaporation rate.

Complete step-by-step answer:
As we are well aware of the key factors that actually affect the rate of evaporation of a liquid in an open system involves the temperature, surface area occupied by the liquid, humidity as well as wind speed. Let us talk about these parameters one by one.

We know that the intermolecular forces tightly hold together the molecules as compared to the gases and thus makes it less likely for the liquid molecules to escape from the surface of the liquid and changes into vapour phase. Thus, we can say that when intermolecular forces are increased, the rate of evaporation decreases.

Next we have temperature which is directly related to the rate of evaporation. So, when we increase the temperature of liquid, the kinetic energy of the surface molecules increases which basically leads to the free movement of molecules thereby increasing the rate of evaporation and hence they are converted to vapours.

Lastly, we have the surface area which is occupied by the liquid, this factor actually increases the rate of evaporation because the molecules on the surface overcome the intermolecular forces of attraction and thus break away from the liquid and become vapours. So in other words we can say that greater the surface area, greater will be the evaporation rate.

Note: Always remember that the liquids do not possess a definite shape thus if surface area and temperature is increased, the evaporation rate increases and if intermolecular forces are increased then it decreases. Hence it is the opposite.