Magnesium chloride

Copper(II) Chloride (CuCl₂)

1. Basic Properties

- Chemical Formula: Anhydrous CuCl₂ (yellow-brown powder) or dihydrate CuCl₂·2H₂O (blue-green crystals).  

- Solubility:  

  - Highly soluble in water (70 g/100 mL, 20°C), aqueous solution is acidic (pH≈3~4).  

  - Soluble in ethanol and acetone.  

- Hygroscopicity: Anhydrous CuCl₂ is deliquescent and must be stored sealed.  

- Melting Point: Approximately 630°C (decomposes).  

2. Main Uses 

- Catalyst:  

  - Organic synthesis (e.g., Sandmeyer reaction for aryl chlorides).  

  - Desulfurizing agent in the petroleum industry.  

- Electroplating: Component of copper plating electrolytes.  

- Pigment: Blue or green coloring agent for ceramics/glass.  

- Laboratory:  

  - Source of copper ions (Cu²⁺) for electrochemical experiments.  

  - Detection of reducing sugars (one component of Fehling's reagent).  

- Others:  

  - Wood preservative, insecticide (use with caution).  

3. Safety and Toxicity 

- Health Hazards:  

  - Inhalation or ingestion irritates the respiratory and digestive tracts; long-term exposure may damage the liver and kidneys.  

  - Skin contact may cause dermatitis.  

- Environmental Risks: Highly toxic to aquatic life (waste liquids must be strictly treated).  

- Protective Measures: Wear gloves and goggles during handling; avoid dust dispersion.  

4. Chemical Properties and Reactions 

- Hydrolysis Reaction: Aqueous solution is acidic (Cu²⁺ hydrolysis):  

- Reaction with Alkalis: Forms blue copper hydroxide precipitate:  

- Reduction Reaction:  

  - With metallic iron (displacement reaction):  

  - With potassium iodide (redox reaction):  

5. Precautions

- Storage: Anhydrous CuCl₂ must be kept moisture-proof; hydrates should avoid high temperatures to prevent dehydration.  

- Waste Disposal: Precipitate Cu²⁺ as Cu(OH)₂ by adding alkali before safe disposal.