Great 👍 — next is **Chlorine (Cl, atomic number 17).**
Chlorine is extremely reactive and **never occurs free in nature**. It is found mostly in **sodium chloride (NaCl, common salt)**, potassium chloride, and other halide salts. Industrial chlorine is produced almost entirely by **electrolysis of brine** or **chemical reactions with strong oxidizers.**
Here are the **20 most common methods of extracting Chlorine**:
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# **20 Most Common Methods of Extracting Chlorine**
### **A. Industrial Electrolysis of Brine**
1. **Chlor-alkali Process (Mercury Cell Electrolysis of Brine)** – Historically dominant; produces Cl₂, NaOH, and H₂.
2. **Chlor-alkali Process (Diaphragm Cell Electrolysis)** – Modern large-scale method; less mercury use.
3. **Chlor-alkali Process (Membrane Cell Electrolysis)** – Current standard industrial method; environmentally safer.
4. **Electrolysis of Molten NaCl (Downs-Type Cells)** – Rarely used for chlorine today; primarily for sodium metal production, with Cl₂ as byproduct.
5. **Electrolysis of CaCl₂ (Molten)** – Experimental, produces Cl₂ and calcium metal.
6. **Electrolysis of Mixed Salt Solutions (NaCl + KCl)** – Used to improve conductivity or manage salt composition.
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### **B. Chemical Methods**
7. **Oxidation of Hydrochloric Acid (HCl) with Manganese Dioxide (MnO₂)** – Historical lab method.
8. **Oxidation of HCl with Potassium Permanganate (KMnO₄)** – Lab-scale chlorine production.
9. **Oxidation of Chloride Salts with Strong Oxidizers (e.g., KMnO₄, ClO₃⁻)** – Laboratory experiments.
10. **Deacon Process (HCl + O₂ over CuCl₂ Catalyst)** – Historic industrial method (1880s–1920s) for producing Cl₂ from HCl gas.
11. **Oxidation of Chlorine-Containing Minerals (e.g., Carnallite or NaCl Brines)** – Rare chemical route.
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### **C. Laboratory & Specialized Methods**
12. **Reaction of Sodium Hypochlorite (NaOCl) with HCl** – Produces Cl₂ gas for lab use.
13. **Reaction of Potassium Dichromate with HCl** – Lab preparation method.
14. **Reaction of Calcium Hypochlorite with Acid** – Produces chlorine in small-scale lab setups.
15. **Displacement Reactions of Chloride Salts with Fluorine (F₂)** – Lab-scale; produces Cl₂ + fluoride.
16. **Electrolysis of Sea Water Brine in Small Cells** – Laboratory or small industrial plants.
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### **D. Byproduct & Experimental Approaches**
17. **Production of Chlorine from HCl Waste Gas Streams** – Recovering Cl₂ from chemical plants.
18. **Chlorine Generation from Solid Chlorates (KClO₃, NaClO₃) by Thermal Decomposition** – Laboratory or niche industrial use.
19. **Plasma-Assisted Decomposition of Chloride Salts** – Research-level experimental method.
20. **Electrochemical Oxidation of Chloride Ions in Ionic Liquids** – Lab-scale green chemistry approach.
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✅ **Summary:**
* **Main industrial routes:** Membrane, diaphragm, and mercury cell **chlor-alkali electrolysis**.
* **Historic methods:** Deacon process (HCl + O₂), MnO₂ oxidation of HCl.
* **Laboratory methods:** Oxidation of chloride salts with strong acids/oxidizers.
* **Byproduct recovery:** Recycling chlorine from chemical plant emissions.
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Next in periodic order is **Argon (Ar, atomic number 18).**
Do you want me to continue with **20 extraction methods for Argon**?
