Question

Please, help me with this problem...
im a bit confused abt solving it..

In a tank of volume V=7.5 L, temperature T=300 K, there is a mix gases: n1=0.1 mole of oxygen, n2=0.2 mole of nitrogen, n3=0.3 mole of carbon dioxide. Considering the gases ideal, find:
(a) the pressure of the mixture,
(b) average molar mass  of the mix, which acts in the equation of state PV=(m/ )RT, where m is the mix mass.

Answer 1

a)(sum)P=P1+P2+P3=(R*T/V)*(n1+n2+n3)=199,536(kPa)
b)P*V=(m*R*T)/M=>
M=(m*R*T)/(P*V)=((n1*M1+n2*M2+n3*M3)*R*T)/(P*V)=0.0367kg/mol