The ionization energy of a hydrogen atom is `epsi_(ion)=13.6eV`. Yet the ionization of hydrogen atoms is observed at temperatures for which the average kinetic energy is much less. How can this fact be explained?

Explanation

Usually the computations are carried out using the relation . This, however, yields too large a value for the temperature:

In fact, ionization takes place at lower temperatures. The reason is the Maxwellian molecular speed distribution, according to which in equilibrium conditions there is always a noticeable percentage of molecules with speeds exceeding the average. For example, from Table 25.1 it may be seen that `(9)/(368)~~2,5%` of the molecules have a speed more than three times the average. This means that nine times greater than the average kinetic energy of the molecules.