# Air is approximately 21% #O_2# and 78% #N_2# by mass. What is the root-mean-square speed of each gas at 273 K?

##### 1 Answer

The

#### Explanation:

The relation between molecular kinetic energy and temperature is given by the equation

where

Solving this for

where the final relation is given in terms of the gas constant

Inserting values gives

Using

and using 0.028 kg for nitrogen

Note that the molar mass had to be changed to kg per mole in order to be consistent with the other units in the equation.