Sodium chloride (data page)
Sodium chloride, also known as salt (though "salt" is a broader chemical term), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is a crystalline solid at room temperature and pressure. Sodium chloride is essential for life in most organisms, including humans, and plays a crucial role in various biological processes such as nerve function and fluid balance.
Physical Properties:
- Appearance: Colorless or white crystalline solid. Can appear colored due to impurities.
- Odor: Odorless.
- Melting point: 801 °C (1474 °F; 1074 K).
- Boiling point: 1,413 °C (2,575 °F; 1,686 K).
- Density: 2.165 g/cm3.
- Solubility: Highly soluble in water. Solubility decreases with increasing temperature in saturated solutions.
- Crystal Structure: Cubic (face-centered cubic, FCC).
- Molar mass: 58.44 g/mol.
Chemical Properties:
- Sodium chloride is a stable compound under normal conditions.
- It is an electrolyte, meaning its solutions conduct electricity due to the presence of free ions.
- Reacts with strong acids to liberate hydrogen chloride gas (HCl).
- Undergoes electrolysis, breaking down into sodium and chlorine.
Occurrence and Production:
- Sodium chloride is abundant in nature, found in seawater, underground salt deposits (halite), and salt lakes.
- It is produced through several methods, including:
- Evaporation of seawater: A common method, particularly in warmer climates.
- Mining of halite: Underground salt deposits are mined and the salt is purified.
- Solution mining: Water is injected into underground salt deposits to dissolve the salt, and the resulting brine is pumped to the surface and evaporated.
Uses:
- Culinary: A primary seasoning and preservative in food.
- Industrial: Used in the production of chlorine, sodium hydroxide, and other chemicals.
- Medical: Used in intravenous solutions for hydration and electrolyte balance.
- De-icing: Used to lower the freezing point of water and prevent ice formation on roads and sidewalks.
- Water Conditioning: Used in water softeners.
- Agriculture: Can be used as a supplement for livestock.
Safety:
- Sodium chloride is generally considered safe for human consumption in moderate amounts.
- Excessive intake can lead to health problems such as high blood pressure.
- Prolonged exposure to high concentrations of salt dust can irritate the respiratory system.