Chromic Acid - H<sub>2</sub>CrO<sub>4</sub>

What is Chromic acid?

Chromic Acid is a naturally occurring oxide of titanium with a formula H2CrO4. It is also called Tetraoxochromic acid or Chromic(VI) acid. It is usually a mixture made by adding concentrated sulfuric acid (H2SO4) to a dichromate which consists of a variety of compounds and solid chromium trioxide.

Molecular chromic acid – H2CrO4 is similar to sulfuric acid (H2SO4) as both are strong acids, however, only the first proton is lost easily.

Dichromic acid – H2Cr2O7 is the fully protonated form of the dichromate (Cr2O7) ion. Also, it is seen as the product of adding chromium trioxide (CrO3) to molecular chromic acid.

Properties of Chromic acid – H2CrO4

Chromic acid

H2CrO4

Molecular Weight of Chromic acid

118.008 g/mol

Density of Chromic acid

1.201 g/cm3

Melting Point of Chromic acid

197 °C

Boiling Point of Chromic acid

250 °C

Structure of Chromic acid (H2CrO4)


Structure of Chromic acid

Uses of Chromic acid (H2CrO4)

  • Chromic acid acts as an intermediate in chromium plating,
  • It is used in ceramic glazes, coloured glass.
  • Chromosulfuric acid or Sulfochromic mixture is a strong oxidizing agent which is used to clean laboratory glassware.
  • It has the ability to brighten raw brass and therefore it is used in the instrument repair industry.
  • In the year 1940, it was used in hair dye.

Health hazards

Hexavalent chromium compounds such as chromium trioxide, chromates, chromic acids, and chlorochromate are toxic and carcinogenic. Therefore chromic acid oxidation is used only in the aerospace industry and not on any other industrial scale.

Chromic acids are strong oxidisers and can react violently if mixed with some easily oxidisable organic substances which can cause explosions or fires. In case of any burns caused by this acid, it is treated with a dilute solution of sodium thiosulfate.

Learn more about the physical and chemical properties of Chromic acid (H2CrO4) from the experts at BYJU’S.

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