An oxidizing acid is a Brønsted acid that is a strong

oxidizing agent An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...

. Most Brønsted acids can act as oxidizing agents, because the acidic proton can be reduced to

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

gas. Some acids contain other structures that act as stronger oxidizing agents than hydrogen ions. Generally, they contain oxygen in their anionic structure. These include

nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...

perchloric acid Perchloric acid is a mineral acid with the formula H Cl O4. Usually found as an aqueous solution, this colorless compound is a stronger acid than sulfuric acid, nitric acid and hydrochloric acid. It is a powerful oxidizer when hot, but aqueous s ...

chloric acid Chloric acid, H Cl O3, is an oxoacid of chlorine, and the formal precursor of chlorate salts. It is a strong acid ( p''K''a ≈ −2.7 (''***note: pKa not in agreement with properties in chem box at right'')) and oxidizing agent. Properties Chlo ...

chromic acid The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixtu ...

, and concentrated sulfuric acid, among others.

General properties

Oxidizing acids, being strong oxidizing agents, can often oxidize certain less reactive metals, in which the active oxidizing agent is not H⁺ ions. For example,

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

is a rather unreactive metal, and has no reaction with concentrated

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

. However, even dilute nitric acid can oxidize copper to Cu²⁺ ions, with the nitrate ions acting as the effective oxidant: : 3 Cu + 8 HNO₃ → 3 Cu²⁺ + 2 NO + 4 H₂O + 6 Sometimes the concentration of the acid is a factor for it to be strongly oxidizing. Again, copper has no reaction with dilute sulfuric acid, but in concentrated sulfuric acid, the highly acidic environment and high concentration of

sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...

ions allow the sulfate ions to act as an oxidizing agent: : Cu + 2 H₂SO₄ → SO₂ + 2 H₂O + + Cu²⁺

General properties

See also