The first step in the industrial preparation of nitric acid by the Ostwald process involves the catalytic oxidation of ammonia by atmospheric oxygen. What is the change in the oxidation state of nitrogen in this specific step?

Step-by-step solution

The first step of the Ostwald process is the catalytic oxidation of ammonia to nitric oxide: 4 NH ₃( g ) + 5 O ₂( g ) [ 500 K, 9 bar ] Pt/Rh catalyst 4 NO ( g ) + 6 H ₂ O ( g ) In ammonia ( NH ₃ ), let the oxidation state of nitrogen be x . x + 3(+1) = 0 x = -3 In nitric oxide ( NO ), let the oxidation state of nitrogen be y . y + (-2) = 0 y = +2 Therefore, the oxidation state of nitrogen changes from -3 to +2 . The option -3 to +4 incorrectly assumes NO ₂ is the primary product of the first step, while -3 to +5 in