When 2,500 liters of natural gas (92 mol% CH4 and 8 mol% N2) at 50 C and 1.75 atm are fed to the burner of a boiler, methane reacts with oxygen from the air (which is fed in stoichiometric amounts), according to the following reaction:

CH4+O2CO2+H2O

with a yield of 97%. The gases obtained after the reaction leave the burner at 40 C and 1 atm. Determine: a) The density of the gases at the burner outlet. b) The average molecular weight of the gases at the outlet of the reactor.