Look at the given, you were given the Pressure (P), Temperature (T), Volume (V) and mass (m) of an unknown gas.
P = 79.97 kPa
V = 4.167 L
m= 20.83 g
Based on the given, you can definitely use the Ideal Gas Law equation to find the molar mass of the gas, where R is a constant equal to
But first, we need to convert units:
Now we are ready to compute.
Since molar mass is defined as weight of substance over the number of moles substance or
Therefore, the molar mass of the unknown gas is 157.56 g/mol.