Chromic acid, with the chemical formula H2CrO4, is an inorganic compound that contains chromium in its +6 oxidation state. It is a strong oxidizing agent and a corrosive, reddish-brown, or dark red solution in water. Chromic acid is a powerful reagent used in various industrial and laboratory applications.

Preparation of Chromic Acid: Chromic acid can be prepared by dissolving chromium trioxide (CrO3) in water:

CrO3 + H2O → H2CrO4

However, due to the hazards associated with handling chromium trioxide, chromic acid is often generated in situ by mixing sodium dichromate (Na2Cr2O7) or potassium dichromate (K2Cr2O7) with an acid, usually sulfuric acid (H2SO4):

Na2Cr2O7 + 2 H2SO4 → H2CrO4 + Na2SO4 + H2O

Properties and Uses of Chromic Acid:

• Appearance: Chromic acid is a deep red solution, sometimes referred to as a “chromic acid solution.”
• Oxidizing Agent: It is a powerful oxidizing agent and can react with various substances, often converting organic compounds into carboxylic acids or aldehydes.
• Cleaning and Etching: Chromic acid solutions are used for cleaning glassware, metal surfaces, and other laboratory equipment. They are also employed for etching or cleaning materials in industrial applications.
• Chromium Plating: Chromic acid is utilized in the electroplating industry for chromium plating, creating a protective and decorative chromium layer on various metals.
• Wood Treatment: Chromic acid has been historically used for wood preservation and as a wood sealer. However, its use has declined due to environmental concerns.

Safety Considerations: Chromic acid and chromium trioxide are highly toxic and corrosive substances. They can cause severe skin burns, respiratory irritation, and other health hazards. Proper safety precautions, including the use of appropriate personal protective equipment (PPE) and handling in a well-ventilated area or under a fume hood, should be followed when working with chromic acid or its related compounds.

Due to its hazardous nature, the use of chromic acid has become more restricted in recent years, and safer alternatives are often preferred for various applications.

As with all hazardous chemicals, it is essential to consult the Material Safety Data Sheet (MSDS) and follow strict safety protocols when working with chromic acid.