Chemistry Easy Partial Pressures.?

Question

2. Calculate the density of air in g/L, assuming air is 20.0% O2 and 80.0% N2,at the temperature and the pressure of the laboratory.

Knowns and some of the work done:
Barometric Pressure. 760.3mmHg
1.00039atm.

Temp: 297.7K

Ptotal=PO2+PN2

1.00039x.2=.200079 atm O2
1.00039x.8=.800316 atm N2

R=.08206

Answer 1

The fastest way to do this is to find a pseudo-molecular weight for air. From the 20/80 assumption, MW = .2*32+.8*28=28.8 g/g-mol
Now find the volume of 1 mode of ideal gas at lab conditions. Then divide the mole wt/volume to get density.

Answer 2

2 NO + Br2 > 2NOBr Kp = P(NOBr)2 / { P(NO) P(Br2)2 } remedy for the Kp making use of the 1st set of documents, and then use that Kp to remedy for the unknown partial tension interior the 2d set.