Which substances are primarily used in the production of nitric acid during the Ostwald process?

The Ostwald process is a critical industrial method for producing nitric acid, where the primary substances involved are ammonia and oxygen. In this process, ammonia gas is oxidized in the presence of oxygen to produce nitric oxide, which is then further oxidized and absorbed in water to form nitric acid.

The reaction begins with the combustion of ammonia in the presence of air (oxygen). This step is vital because the oxidation of ammonia forms nitric oxide, which is an intermediate in the formation of nitric acid. The overall reaction can be simplified as:

[ 4 NH_3 + 5 O_2 → 4 NO + 6 H_2O ]

Subsequently, the nitric oxide can react with additional oxygen:

[ 2 NO + O_2 → 2 NO_2 ]

Finally, nitrogen dioxide can dissolve in water to form nitric acid:

[ 3 NO_2 + H_2O → 2 HNO_3 + HNO ]

Thus, the correct answer reflects the essential reactants used in the Ostwald process to effectively produce nitric acid.