A reaction produced 55.7 mL of nitrogen gas, which was collected over water at 23oC. The measured barometric pressure was 742 torr. If the vapor pressure of water at 23oC is 21 torr, what was the mole fraction of N2 in the collected gas?

Answer 1

Ptotal = PH2O + PN2
You know Ptotal and PH2O, solve for PN2.

Then XN2 = PN2/Ptotal