This article provides answers to the following questions, among others:

• How can the evaporation of liquids be explained?
• Why does a cooling effect occur during evaporation?
• Why does one freeze faster with wet skin than with dry skin?

Maxwell-Boltzmann distribution of ideal gases

The figure below shows the speed distribution according to Maxwell-Boltzmann for the particles of an ideal gas. Put simply, this distribution shows the number of particles (vertical axis) for a certain velocity (horizontal axis). Figure: Speed distribution of an ideal gas for different temperatures

Temperature has a major influence on this distribution. For higher temperatures, the curves are squeezed in height and stretched in length. This results in a greater distribution with higher speed proportions. This corresponds to the fact that the temperature is a measure of the kinetic energy of the gas particles: the higher the temperature, the greater the kinetic energy and thus the velocity of the particles (see also the article Temperature and particle motion).

With increasing temperatures, the curve maximum shifts to higher speeds!

In principle, all curves are open to the right, i.e. even at such low temperatures, there is a certain probability that particles with extremely high speeds can be found.

Even at very low temperatures, there are gas particles that have very high speeds!

Evaporation

If this fact is now qualitatively transferred from ideal gases to liquids, this means that even below the boiling point particles are always found with sufficiently high velocities. Due to the associated high kinetic energy, these particles can escape the attractive forces of the liquid. Such a process is called evaporation and takes place far below the boiling point.