91Ó°ÊÓ

The average translational kinetic energy of the molecules in random motion, in an ideal gas, is directly proportional to the absolute temperature of the gas.

The average translational kinetic energy is \(\overline {KE} = \frac{3}{2}kT\).

Here, k is the Boltzmann constant.

A vacuum is a space that does not contain any particle. The temperature of an object or space can be found by determining the average kinetic energy of the molecules present in it. Since no molecules are present in the perfect vacuum, there is no kinetic energy in it. Thus, the temperature of the perfect vacuum cannot be determined.

However, it is quite difficult to create the perfect vacuum. Generally, a few molecules are left in the ordinary vacuum, using which its temperature can be determined.