The initial concentration of NO2 in a closed container is 0.750M. At equilibrium the concentration of O2 is 0.125M. What are the concentrations of NO2 and NO at equilibrium?

Question

2NO2 (aq) ==== 2NO (aq) + O2 (aq)

DrBob222 · Answer

......2NO2 (aq) ==== 2NO (aq) + O2(aq)
I....0.750............0..........0
C......-2x.............2x.........x
E....0.750-2x..........2x.........x

So the problem tells you x [which is (O2)] = 1.25M which makes 2x (the concn of NO) just twice that. NO2 then is 0.75-2x