Perchloric acid - HClO4

What is Perchloric acid?

HClO4 is is a chlorine oxoacid with chemical name Perchloric acid. It is also called Hyperchloric acid (HClO4) or hydroxidotrioxidochlorine. Between 50% -72% acid is a clear odorless colorless aqueous solution. It is corrosive to tissue and metals. When closed containers are exposed to heat for a long duration can rupture violently.

Properties of Perchloric acid – HClO4


Perchloric acid

Molecular weight of HClO4

100.46 g/mol

Density of Perchloric acid

1.768 g/cm3

Melting point of Perchloric acid

−17 °C

Boiling point of Perchloric acid

203 °C

Perchloric acid structure – HClO4

Perchloric acid structure

HClO4 Uses (Perchloric acid)

  • Perchloric acid is used as an oxidizer in the separation of sodium and potassium.
  • Used in making explosives.
  • Used for plating of metals.
  • Used as a reagent to determine the 1H-Benzotriazole
  • Used as a catalyst.
  • Used in rocket fuel.
  • Used for electropolishing or etching of molybdenum.

Production of Perchloric acid

At an industrial level it can be produced in two methods. In the traditional method makes full use of the high aqueous solubility of sodium perchlorate (NaClO4). Treating this solution with hydrochloric acid (HCl) produces perchloric acid by precipitating solid sodium chloride. The reaction is as follows:

NaClO4 + HCl → NaCl + HClO4

The other method is more direct and keeps away from salts and requires anodic oxidation chlorine solution at a platinum electrode.

It can also be prepared in laboratories by treating barium perchlorate (Ba(ClO4)2) with sulfuric acid (H2SO4) which precipitates barium sulfate (BaSO4) and leaves perchloric acid. Alternately it can be prepared by mixing nitric acid (HNO3) with ammonium perchlorate (NH4ClO4) and add hydrochloric acid while its boiling.

Health hazards

Inhaling vapours of this compound causes burning sensation in the throat and nose, irritation in lung along with coughing. Prolonged exposure causes vomiting. Ingesting this compound can cause blistering and burns in stomach. When heated it liberates corrosive, irritating, and toxic gases.

Learn more about the Structure, physical and chemical properties of HClO4 from the experts at BYJU’S.

Leave a Comment

Your email address will not be published. Required fields are marked *