I've been trying to figure out how to go about answering this question and don't even know where to start. Any help would be greatly appreciated

Question

The oxidation of NH3 to NO in the Ostwald process must be very carefully controlled in terms of temperature, pressure, and contact time with the catalyst. This is because the oxidation of NH3 can yield any one of the products N2, N2O, NO and NO2, depending on the conditions. Show that the oxidation of NH3 to N2 is the most exothermic of the four possible reactions.

Answer 1

One way, is to write the balanced reaction for each of the three cases, then compute the Gibbs Free Energy of each.

Answer 2

Thank you!