The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid

Sulfuric acid

Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 to a dichromate, which may contain a variety of compounds, including solid chromium trioxide

Chromium trioxide

Chromium trioxide is the inorganic compound with the formula CrO3. It is the acidic anhydride of chromic acid, and is sometimes marketed under the same name.This compound is a dark-red/orange brown solid, which dissolves in water concomitant with hydrolysis...

. This kind of chromic acid may be used as a cleaning mixture for glass. Chromic acid may also refer to the molecular species, H₂CrO₄ of which the trioxide is the anhydride

Acidic oxide

An acidic oxide is an oxide that either*reacts with water to form an acid; or*reacts with a base to form a salt.Examples include:...

. Chromic acid features chromium in an oxidation state

Oxidation state

In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...

  of +6 (or VI).