Question

A glass is semifilled with liquid water and place in a room at 20 oc. after some time, part of the water evaporates. what happened to the average kinetic energy and the average potential energy of the water particles that escaped to the gas phase?

Answer 1

Water is placed at room temperature at 20 degree C

now after some water evaporate at room temperature

so here we can say speed of water molecules will not change as the temperature is same after evaporation

as we know that total kinetic energy is given by

$KE = \frac{f}{2} nRT$

since temperature is same then energy will not change here

now as water evaporate to vapors then we can say that here all molecules are separated more in vapor phase so force of interaction will be less in this phase

And since potential energy depends on the force so potential energy will decrease in this phase