In Ostwals's process for the manufacture of nitric acid, the first step involves the oxidation of ammonia gas by oxygen gas to give nitric oxide gas and steam. What is the maximum weight of nitric oxide that can be obtained starting only with 10.00 g. ammonia and 20.00 g of oxygen?
The balanced chemical equation for the given reaction is given as:
4NH3(g)+5O2(g)⟶4NO(g)+6H2O(g)
4×17g 5×32g 4×30g 6×18g
=68g =160g =120g =108g
Thus, 68g of NH3 reacts with 160 g of O2
Therefore, 10g of NH3 reacts with 160×1068g of O2 or 23.53g of O2.
But the available amount of O2 is 20 g.
Therefore, O2 is the limiting reagent (we have considered the amount of O2 to calculate the weight of nitric oxide obtained in the reaction).
Now, 160 g of O2 gives 120g of NO.
Therefore, 20 g of O2 gives 120×20160g of N, 15g of NO.
Hence, a maximum of 15g of nitric oxide can be obtained.