Well I forgot to mention the percentage amounts to take into consideration. In this case we know there is more oxygen, which is 32.00 g/mol, and nitrogen molar mass plus oxygen molar mass is obviously greater. But I forgot the percentages, so this isn't as intuitive as I first thought.

We aren't adding 1 L, we're assuming densities at STP, which is 22.44 L. So the volume is 22.41, not 1.

But I see my mistake. Forgot the volumes too. I just try to rationalize through things before calculating.