Copper I Chloride: Preparation, Properties and Uses

Copper is a chemical element with the symbol Cu with atomic number 29 in its periodic table. It is soft and has very high thermal and electrical conductivity. It is pinkish-orange in color. Chlorine (Cl) is a greenish-yellow gas with atomic number 17 in the periodic table. It has a pungent odor-like smell. This gas is harmful to nature, it is 2-5 times denser than air. It is the 2nd lightest halogen among all the elements. It has two isotopes, that are stable.


Chemical FormulaCuCl
Molecular WeightApproximately 98.996 g/mol
Physical StateSolid
AppearanceWhite to pale yellow powder or crystalline solid
Melting Point430°C (806°F)
Boiling Point1490°C (2714°F)
Density~4.14 g/cm3 (at 20°C)
SolubilitySoluble in water, insoluble in organic solvents
pHAcidic (in solution)
Crystal StructureZincblende
Magnetic PropertiesDiamagnetic
Thermal Conductivity~90 W/m·K (at 25°C)
Electrical ConductivityInsulator (in solid state), conducts electricity when dissolved in water or molten
Hazard SummaryIrritant to eyes, skin, and respiratory tract; may cause irritation or burns; harmful if ingested or inhaled.

Preparation of Copper I Chloride

Materials Needed:

  1. Copper(II) chloride (CuCl2)
  2. Reducing agent (such as sulfur dioxide gas, hydrogen gas, or ascorbic acid)
  3. Concentrated hydrochloric acid (HCl)
  4. Distilled water
  5. Glassware (such as beakers, flasks, and stirring rods)
  6. Heating apparatus


  • Dissolve copper(II) chloride (CuCl2) in distilled water to form a solution. This can be done in a beaker or flask.CuCl2(aq) + H2O(l) → Cu^2+(aq) + 2Cl^-(aq)
  • Add a reducing agent to the copper(II) chloride solution. The reducing agent will reduce copper(II) ions (Cu^2+) to copper(I) ions (Cu^+), forming copper(I) chloride. Depending on the reducing agent used, the reaction may proceed differently:
    • With Sulfur Dioxide (SO2): SO2(g) + 2H2O(l) → H2SO3(aq) H2SO3(aq) + 2CuCl2(aq) → 2HCl(aq) + 2CuCl(s) + SO2(g)
    • With Hydrogen Gas (H2): CuCl2(aq) + H2(g) → 2HCl(aq) + 2CuCl(s)
    • With Ascorbic Acid (Vitamin C): C6H8O6(aq) + CuCl2(aq) → 2HCl(aq) + 2CuCl(s) + C6H6O6(aq)
    Ensure proper safety precautions are taken, especially with gases.
  • Stir the solution to ensure thorough mixing and reaction.
  • Allow the reaction to proceed until copper(I) chloride precipitates out of the solution.
  • Filter the precipitated copper(I) chloride using a filter paper and a funnel to separate it from the solution.
  • Wash the precipitate with distilled water to remove any impurities.
  • Dry the copper(I) chloride by either allowing it to air dry or using gentle heating.
  • Once dried, store the copper(I) chloride in a dry and labeled container for future use.

Uses of Copper I Chloride

  • Catalysis: Copper(I) chloride is used as a catalyst in various organic reactions, such as the Ullmann reaction, which involves the synthesis of biaryl compounds. It also finds applications in the synthesis of pharmaceuticals, agrochemicals, and fine chemicals.
  • Polymerization: It serves as a catalyst or co-catalyst in the polymerization of ethylene and other olefins to produce polyethylene and other polyolefins. This usage is particularly prevalent in industrial polymerization processes.
  • Pigments: Copper(I) chloride can be used as a pigment in ceramics, glass, and paints. Its color can vary depending on the size of the particles and the method of preparation, ranging from white to various shades of green.
  • Wood Preservative: It is utilized in wood preservatives to protect timber from decay caused by fungi and other organisms. Copper(I) chloride-based wood preservatives are effective and have been used for outdoor applications.
  • Photography: In traditional black and white photography, copper(I) chloride is used in sensitizing solutions to enhance the sensitivity of photographic emulsions to red light. It helps in the formation of latent image centers during the exposure process. However, with the decline of traditional photography, this use has become less common.