Question

In the reaction for nh3 + 5 o2 equals to 4 and + 6 h2o when 1 mole of ammonia and 1 mole of oxygen are made to react

Answer 1

You can see in the balanced reaction that the Ammonia and Oxygen required are in the ratio 4:5

Thus 4 moles of Ammonia requires 5 moles of oxygen.

4 NH3 ≈ 5O2

1 NH3 ≈ 1.25 O2

Now we have oxygen in less quantity as compared to Ammonia, thus Oxygen is the limiting reagent. So we balance to suit Oxygen.

4NH3 ≈ 5O2

0.8 NH3 ≈ 1 O2

Thus the reaction becomes

0.8 NH3 + 1 O2 → 0.8 NO + 1.2 H2O

Thus all of the oxygen is used. 0.2 moles of NH3 are unused and we acquire 0.8 moles of NO and 1.2 moles of H2O.