[heromoto96]

correct equation N2+2O2-----=2NO2
here is excess N2 in the rx so there is only 6 moles reacting
and 2 moles excess1
15=the total reacting moles =17-2(the excess
Now the sum of moles of the equation 5x=15 x=3
The eq now is 3N2+6O2------=6NO2