The most interesting oxide to us at the moment is the one with the highest oxidation number, . When this compound is added to water, it forms nitric acid, one of the standard reagents of the chemical laboratory:



(There are safer ways of making nitric acid for commercial purposes.)

Nitric acid is much stronger than carbonic acid. It is dissociated completely into protons and nitrate ions in water:



whereas carbonic acid is only partially dissociated, and boric acid is hardly dissociated at all.