An oxidizing acid is a Brønsted acid that is also a strong oxidizing agent . All Brønsted acids can act as moderately strong oxidizing agents, because the acidic proton can be reduced to hydrogen gas. Some acids contain other structures that act as stronger oxidizing agents than hydrogen. Generally, they contain oxygen in the anionic structure. These include nitric acid, perchloric acid, chloric acid, chromic acid, and concentrated sulfuric acid, among others. For example, copper metal cannot be oxidized by and dissolved in a non-oxidizing acid, because it is lower on the reactivity series than acidic hydrogen, but an oxidizing acid such as nitric acid can oxidize the copper, and allow it to react.