O in CO is -2 C in CO is +2 O in CO₂ is -2 C in CO₂ is +4
O₂ is 0 N₂ is 0 N in NO₂ is +4 O in NO₂ is -2
Reaction #1: exothermic Reaction #2: exothermic
What more can be said about the oxidation number of the element in the reaction?
Oxygen typically has an oxidation number of -2.
The compound is neutral, so the sum of oxidation numbers must be 0. Therefore, carbon (C) in CO must have an oxidation number of +2.
In CO₂, the total oxidation number for oxygen is 2(-2) = -4. To balance this, the oxidation number of carbon must be +4.
In a diatomic molecule like O₂, the oxidation number for oxygen is 0.
N2 (Nitrogen Gas):
Similarly, in diatomic nitrogen (N₂), the oxidation number for nitrogen is 0.
Reaction 1 (2NO₂(g) + 4CO(g) → N₂(g) + 4CO₂(g) + 1198.4 kJ):
This reaction is exothermic because it releases energy (1198.4 kJ).
Reaction 2 (2CO(g) + O₂(g) → 2CO2(g) + 566.0 kJ):
This reaction is also exothermic, as it releases energy (566.0 kJ).