According
to the kinetic theory, all submicroscopic particles of all mater are in
constant random motion. This means that gas particles are zipping
and bouncing within their container. As a result, these particles
have kinetic energy. Although all particles are in constant motion,
they do not all have the same kinetic energy. Some particles can
be moving really fast while others can be moving moderately fast. Therefore,
not all particles have the same speed. This same idea applies to
an air filled balloon. All the gas particles are moving randomly
in the balloon at different rates.
According to the kinetic theory, the temperature of a substance is a measure of the average kinetic energy of the particles that make up the substance. For example, as a gas is heated, the average kinetic energy of its particles increases. This increase in the average kinetic energy of the particles of the gas can be measure as an increase in the temperature of a gas. As the gas cools to room temperature, the average kinetic energy and speed of its particles decreases. The figure below shows the direct relationship between temperature and average kinetic energy.
One of the many misconceptions that students have is that if you increase the temperature of a gas, the size of the gas particles increase in size. Although many students such as those discussed in the student's ideas page, it is important to realize that this is not the case. An increase in temperature only causes the gas particles to move faster and expand, not increase in size!
Since temperature is a direct measurement
of the average kinetic energy of gas particles, temperature is one of the
four
variables that are used to describe gases.