Magnesium chloride (MgCl₂) is a versatile and important inorganic compound used in various industries and applications. Here’s a comprehensive introduction to magnesium chloride:

Chemical Properties and Forms

Chemical Formula: MgCl₂

Molecular Weight: 95.211 g/mol

Appearance: It can appear as white, crystalline solids or a colorless, aqueous solution.

Forms:

  Anhydrous Magnesium Chloride: The dry, salt-like form.

  Hexahydrate (MgCl₂·6H₂O): The most common form, which contains six water molecules bound to each magnesium chloride molecule, usually appearing as white, crystalline flakes.

Production

Magnesium chloride is produced through several methods:

Seawater Extraction: Magnesium chloride is often extracted from seawater or brine, which contains significant amounts of magnesium salts.

Mineral Sources: It can also be derived from natural minerals like carnallite (KMgCl₃·6H₂O) or from the processing of other magnesium-containing minerals.

Chemical Processes: Other methods include the reaction of hydrochloric acid with magnesium oxide or hydroxide.

Key Properties

Solubility: Magnesium chloride is highly soluble in water, forming a clear, colorless solution. Its solubility increases with temperature.

Hygroscopicity: The anhydrous form is hygroscopic and absorbs moisture from the air, turning into a solution if exposed to high humidity.

Major Uses

1. De-icing and Anti-icing: Used on roads and highways during winter to melt ice and improve traction. It is preferred in some regions due to its lower environmental impact compared to other de-icing agents.

2. Water Treatment: Employed as a coagulant in water and wastewater treatment to help remove impurities.

3. Industrial Applications:

   Magnesium Production: Serves as a feedstock in the production of magnesium metal through electrolysis.

   Building Materials: Used in the manufacture of magnesium-based cement and concrete, which have fire-resistant properties.

4. Agriculture: As a soil conditioner and magnesium supplement for plants.

5. Medical Uses: Magnesium chloride is used in various pharmaceutical applications and as a dietary supplement to address magnesium deficiencies.

6. Chemical Processes: It is a starting material for producing other magnesium compounds.

Safety and Handling

Safety: Magnesium chloride is generally safe to handle, but it can cause irritation if it comes into contact with the skin or eyes. It is important to follow safety guidelines and use personal protective equipment when handling the compound in industrial settings.

Storage: Should be stored in a cool, dry place to prevent moisture absorption and degradation of the material.

Environmental Impact

Magnesium chloride is considered to have a lower environmental impact compared to some other de-icing salts. It is less corrosive to infrastructure and vehicles, and it does not have the same level of ecological damage as chloride salts like sodium chloride.

Magnesium chloride’s versatility and utility across various sectors make it a significant compound in both industrial and everyday applications.