Find the total translational kinetic energy of 1.5 l of oxygen gas held at a temperature of 0°c and a pressure of 0.8 atm.

The ideal gas law states that:

where
p is the gas pressure
V is its volume
n is the number of moles
R is the gas constant
T is the absolute temperature

However, this equation can be also rewritten as
(1)
where
N is the number of molecules in the gas, and K is the average kinetic energy of the molecules. Therefore, NK represents the total kinetic translational energy of the gas.

For the gas in our problem,


So, the total translational kinetic energy of the gas is (using eq.(1) )