Redox reactions may involve proton transfers and other bond-breaking and bond-making processes, as well as electron transfers, and also therefore the equations involved are much more complicated to attend to than those describing acid-base reactions. In stimulate to be able to recognize redox reactions, we need a an approach for maintaining a mindful account of every the electrons. This is excellent by assigning oxidation number to each atom before and after the reaction.

You are watching: What is the oxidation number of nitrogen in nitric acid, hno3?

For example, in NO3– the nitrogen is assigned an oxidation number of +5 and also each oxygen an oxidation variety of –2. This arbitrary assignment synchronizes to the nitrogen’s having actually lost that is original 5 valence electron to the electronegative oxygens. In NO2, ~ above the other hand, the nitrogen has an oxidation variety of + 4 and also may be assumed of as having one valence electron because that itself, the is, one much more electron than it had in NO3–.

This arbitrary assigned gain of one electron synchronizes to reduction of the nitrogen atom ~ above going native NO3– come NO2. Together a basic rule, reduction coincides to a lowering of the oxidation variety of some atom. Oxidation synchronizes to boosting the oxidation number of some atom. Using the oxidation number rule to the adhering to equation, us have

api/deki/files/71193/7e3520554330bd1c1248fba1651c6194.png?revision=1&size=bestfit&width=500&height=35" />The just atoms which adjust are Mn, indigenous +7 come +2, a reduction, and also S, native +4 come +6, an oxidation. The reaction is a oxidization process. SO2 has been oxidized by MnO4–, and so MnO4–is the oxidizing agent. MnO4– has been diminished by SO2, and also so SO2 is the reduce agent.

See more: Ep-1 What Should You Do If You Suddenly Find Yourself In Cold Water?

b) The oxidation numbers


show the no redox has occurred. This is one acid-base reaction since a proton, yet no electrons, has been transferred.