Magnesium hydroxide (Mg(OH)2) is a white, odourless solid with many applications. It's commonly used in medicine as an antacid to neutralise stomach acid and relieve indigestion. In addition, it serves as a critical component in laxatives and oral care products. Industrial applications include its use as a flame retardant in plastics and textiles and wastewater treatment to adjust pH levels and remove heavy metals. This compound is favoured for its low toxicity and environmental compatibility, making it a versatile solution in various fields, from healthcare to manufacturing and environmental protection.

The chemical formula of magnesium hydroxide is Mg(OH)2. Structurally, one magnesium (Mg) ion bonded to two hydroxide (OH-) ions through ionic bonds. In its solid state, magnesium hydroxide forms a crystal lattice structure where hydroxide ions surround magnesium ions. This arrangement produces a white, crystalline solid with a layered or hexagonal crystal structure, depending on the formation conditions.

Appearance: Magnesium hydroxide typically appears as a white, odourless powder or fine crystalline solid.

Density: Its density varies depending on the form and generally ranges from 2.36 to 2.40 g/cm³.

Melting Point: Magnesium hydroxide has a relatively high melting point of approximately 350°C (662°F).

Solubility: It is sparingly soluble in water, with a solubility of about 0.0009 g/100 mL at 25°C. However, its solubility increases with temperature.

pH: When magnesium hydroxide is dispersed in water, it forms a suspension with a slightly basic pH, typically around 10-11 due to the hydrolysis of hydroxide ions.

Hygroscopicity: Magnesium hydroxide is not hygroscopic, meaning it does not readily absorb atmospheric moisture.

Insolubility in Organic Solvents: It is insoluble in organic solvents such as ethanol, acetone, and ether.

These properties make magnesium hydroxide suitable for various applications, including pharmaceuticals, antacids, flame retardants, and industrial processes.

Neutralisation Reaction: Magnesium hydroxide reacts with acids to form magnesium salts and water through a neutralisation reaction. For example: 

Mg(OH)2 + 2HCl → MgCl2 + 2H2O

Amphoteric Nature: Magnesium hydroxide exhibits amphoteric behaviour, meaning it can act as both an acid and a base. It can react with both acids and bases to form salts and water.

Thermal Decomposition: When heated, magnesium hydroxide undergoes thermal decomposition to produce magnesium oxide and water. The reaction can be represented as: Mg(OH)2 → MgO + H2O

Buffering Capacity: In aqueous solutions, magnesium hydroxide can act as a buffer, helping to maintain a relatively constant pH by neutralising excess acid or base.

Precipitation Reaction: Magnesium hydroxide can precipitate from solutions containing magnesium ions and hydroxide ions, often due to pH adjustment or chemical reactions.

Adsorption Properties: Magnesium hydroxide has adsorption capabilities, which make it useful in various applications such as wastewater treatment, where it can adsorb heavy metal ions and organic pollutants.

Understanding these chemical properties is crucial for utilising magnesium hydroxide in various industrial, environmental, and pharmaceutical applications.

Magnesium hydroxide, seemingly simple in its chemical structure, boasts a remarkably diverse range of applications across various industries. From soothing tummy troubles to safeguarding homes from fire, this versatile compound proves its worth in unexpected, yet impactful ways. Apart from has many other uses in different industries.

Medical:

Antacid: Magnesium hydroxide serves as a potent antacid, swiftly alleviating discomfort associated with heartburn, indigestion, and upset stomach. By neutralising excess stomach acid, it provides rapid relief from these symptoms.

Laxative: In higher doses, magnesium hydroxide transforms into an effective laxative, addressing occasional constipation. Its mechanism involves drawing water into the intestines, softening stool and facilitating bowel movements.

Food Additive: Magnesium hydroxide finds widespread use as a food additive. It plays a crucial role in regulating acidity and adjusting pH levels in diverse food products, ranging from processed cheese and tofu to cocoa powder. Additionally, it functions as an anticaking agent and texture enhancer.

Magnesium Supplement: Certain formulations of magnesium hydroxide serve as a reliable source of supplemental magnesium, a vital mineral for maintaining overall health.

Flame Retardant: Magnesium hydroxide enjoys significant application as a flame retardant in various materials like plastics, textiles, and building materials. Its effectiveness stems from its ability to absorb heat and release water vapour, cooling the material and impeding fire spread.

Neutralizing Agent: This versatile compound has numerous industrial processes for neutralising acidic wastes and effluents.

Cosmetics: Magnesium hydroxide plays a role in several cosmetic products due to its properties as a pH adjuster, absorbent, and buffering agent.