Root Mean Square Speed
The square root of the average of the squared molecular speeds in a gas sample.
Formula / equation
c_rms = √(3RT / M)
Unit
m/s
In depth
The root mean square speed is the value that appears directly in kinetic theory expressions for pressure and kinetic energy, and it is slightly larger than both the mean and the most probable speed. It rises with the square root of temperature and falls with the square root of molar mass.
Examples in the real world
Nitrogen molecules average about 517 m/s at 25 °C, while hydrogen reaches roughly 1930 m/s.