Potassium Chloride (KCl)

1. Basic Properties

- Chemical Formula: KCl  

- Appearance: Colorless or white cubic crystals, highly soluble in water, salty taste (similar to table salt).  

- Solubility:  

  - Highly soluble in water (34.2 g/100 mL, 20°C), slightly soluble in ethanol  

  - Aqueous solution is neutral (pH≈7).  

- Melting Point: 770°C, Boiling Point: 1420°C (volatile at high temperatures).  

- Conductivity: Solid form does not conduct electricity; conductive when molten or dissolved in water (due to K? and Cl? ions).  

2. Preparation Methods 

- Natural Extraction:  

  - Separation from potash ores (e.g., sylvinite, a KCl·NaCl mixture).  

  - Purification via dissolution-crystallization (utilizing solubility differences between KCl and NaCl).  

-3. Main Applications

- Agriculture:  

  - Potassium fertilizer (provides essential K? ions for plants, promoting crop growth).  

- Industry:  

  - Production of metallic potassium (electrolysis of molten KCl).  

  - Manufacture of potassium hydroxide (KOH, via electrolysis of KCl solution).  

  - Production of other potassium compounds (e.g., KNO?, K?SO?).  

- Food:  

  - Low-sodium salt substitute (partially replaces NaCl, used for hypertensive patients).  

- Medicine:  

  - Treatment of hypokalemia (injection or oral preparations).  

  - Antidote (e.g., for digitalis poisoning).  

- Laboratory:  

  - Preparation of buffer solutions or standard reagents.  

4. Safety Precautions

- Toxicity:  

  - Generally safe with normal use, but high-dose intake (>2.5 g/kg) can cause hyperkalemia, leading to arrhythmias or even cardiac arrest.  

- Protection:  

  - Avoid inhaling powder (irritates respiratory tract); wear gloves during handling.  

- Storage: Keep sealed and moisture-proof (hygroscopic, may clump).