The ideal gas law is:
pV = nRT
where p=pressure, V=volume, n=number of moles, R=gas constant, T=temperature, m=molar mass, M=mass
Setting up for M1 and M2 using the fact that n = M/m
pV1 = M1/m x RT1 ==> M1 = PmV1/RT1
pV2 = M2/m x RT2 ==> M2 = PmV2/RT2
Since volume doesn't change, V1 = V2 =V
The question is to find for the mass of air that enters the room, which is M2 – M1
M2 – M1 = (PmV2/RT2) – (PmV1/RT1 )
