Calcium Hypochlorite, Calcium Oxychloride, Calcium Dihypochlorite, 7778-54-3

Calcium Hypochlorite (CAS 7778-54-3)

Identification

• CAS No: 7778-54-3

• EINECS: 231-908-7

• Molecular Formula: Ca(ClO)₂

• Molar Mass: 142.98 g/mol

• Synonyms: Bleaching powder, Calcium hypochlorite, Calcium dihypochlorite

• UN No: 1748 (Class 5.1, PG II)

• HS Code: 2828 10 00

Physical and Chemical Properties

• Appearance: White to light green tablets or powder

• Odor: Chlorine-like

• Density: 2.35 g/mL (25 °C)

• Melting Point: ~100 °C

• Solubility: 200 g/L in water (20 °C, with decomposition)

• pH: Alkaline solution when dissolved

• Stability: Strong oxidizer; decomposes with moisture, sunlight, heat, and acids

Applications

• Bleaching of cotton, linen, silk, and pulp

• Disinfection of drinking water and swimming pools

• Purification of acetylene

• Oxidizing agent in chemical industry

• Military use as chemical agent and radioactive disinfectant

Production Methods

• Lime process: Passing chlorine gas into slaked lime.

• Sodium process: Chlorination of calcium oxide mixed with sodium hydroxide.

Hazards and Safety

• Risk Codes:

  • R8: Fire risk with combustible materials

  • R22: Harmful if swallowed

  • R31: Toxic gas released with acids

  • R34: Causes burns

  • R50: Very toxic to aquatic organisms

• Safety Measures:

  • Rinse eyes immediately with water if exposed

  • Wear protective clothing, gloves, and goggles

  • Seek medical help in case of accident

  • Prevent release into the environment

• Toxicity:

  • LD50 oral (rabbit): 850 mg/kg

  • LD50 dermal (rabbit): >2000 mg/kg

Storage and Transport

• Store in a cool (15–25 °C), dry, well-ventilated area

• Keep away from organic matter, acids, oils, and reducing agents

• Must be stored separately from flammable materials

• Packing group: II

Summary

Calcium hypochlorite is a powerful oxidizer and disinfectant. It is widely used in textiles and paper bleaching, as well as in water treatment. Due to its instability and reactivity, it requires careful handling, storage, and transport.