Textbook Problem

Ammonia reacts with O₂ to form either NO(g) or NO₂(g) according to these unbalanced equations:

$\begin{array}{l}{\text{NH}}_{\text{3}}\left(g\right)+{\text{O}}_{\text{2}}\left(g\right)\to \text{NO}\left(g\right)+{\text{H}}_{\text{2}}\text{O}\left(g\right)\\ {\text{NH}}_{\text{3}}\left(g\right)+{\text{O}}_{\text{2}}\left(g\right)\to {\text{NO}}_{\text{2}}\left(g\right)+{\text{H}}_{\text{2}}\text{O}\left(g\right)\end{array}$

In a certain experiment 2.00 moles of NH₃(g) and 10.00 moles of O₂(g) are contained in a closed flask. After the reaction is complete, 6.75 moles ofO₂(g) remains. Calculate the number of moles of NO(g) in the product mixture: (Hint: You cannot do this problem by adding the balanced equations because you cannot assume that the two reactions will occur with equal probability.)