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Magnesium Oxide and Magnesium Hydroxide

Introduction of Magnesium Oxide and Magnesium Hydroxide

Magnesium Oxide and Magnesium Hydroxide are two inorganic substances that contain magnesium. Magnesium Oxide also known as magnesia, is a clear solid mineral that has a very high melting point.

It is made through heating of magnesium carbonate, or magnesium hydroxide. MgO is used extensively in a variety of industrial applications including refractories and electrical insulators, as well as an ingredient in anti-acids.

Magnesium Hydroxide on the contrary is a white solid that is crystalline with a lower melting point. It is usually created through the mixing of magnesium salts and sodium hydroxide.

It is mostly used in pharmaceuticals for its use as an anti-cause and laxative because of its capacity to help neutralize acid in the stomach. Mg(OH)2 has environmental applications and is a flame retardant in plastics and as an acid-neutralizing agent in wastewater.

Both compounds have distinct characteristics and uses, making them essential in a variety of sectors and in various contexts.

Definition of Magnesium Oxide

Magnesium Oxide chemically referred to as MgO is an inorganic compound made up of one magnesium atom as well as one oxygen atom that are bonded. It is often referred to as magnesia.

It is an odorless, white, and tasteless liquid that has its chemical formula of MgO. This chemical compound is derived from the mineral naturally occurring magnesite which is the source of magnesium within the Earth’s crust.

Magnesium Oxide
Figure 01: Magnesium Oxide

Magnesium Oxide is a marvelous substance with a range of properties. It has a very high melting point, which is around 2800 degC (5,072degF) which makes it not soluble within water.

If heated to high temperatures it releases an intense white light, which makes it suitable for applications such as the manufacture of magnesium-based flares. This makes it a valuable refractive material in a variety of industries, like the manufacture of cement and steel.

It also serves as an electrical insulator and is used in the manufacture of crucibles, electrical heating components, and insulation powders. Magnesium Oxide is a component in a variety of over-the-counter antacid medications.

Because it is alkaline, it has the ability to neutralize stomach acid, thereby providing relief from heartburn and indigestion. Its many properties and uses make it an important ingredient in a range of fields including pharmaceuticals, metallurgy, and pharma.

Definition of Magnesium Hydroxide

Magnesium Hydroxide, referred to chemically as Mg(OH)2 is an inorganic compound that consists of one magnesium atom as well as two hydroxide molecules. It’s a clear crystallized substance that has low solubility in water, commonly called milk of magnesia as a result of its presence in water.

Magnesium Hydroxide
Figure 02: Magnesium Hydroxide

The chemical is produced by an ion precipitation process that takes magnesium from an insoluble salt such as magnesium chloride, or magnesium sulfate. It is combined with ammonium or sodium hydroxide.

The most well-known applications that are made use of Magnesium Hydroxide can be found in the medical field. It is a well-known laxative and antacid. As an antacid, it functions by neutralizing stomach acid, thereby providing relief from heartburn, indigestion, or acid reflux.

It also functions as a laxative and helps in increasing the retention of water in the intestines, and also encouraging stool movements. Magnesium Hydroxide has applications in the field of environmental engineering.

It’s used as an acidity regulator in wastewater treatment in order to reduce acidic effluents stop corrosion, and assist with the elimination of industrial heavy metals. Its use in health and environmental protection demonstrates its value as a versatile and effective compound.

Chemical Composition

Magnesium Oxide

  • Chemical Formula: MgO
  • It is composed of the magnesium (Mg) element that is bonded to a single oxygen (O) Atom.

Magnesium Hydroxide (Mg(OH)2)

  • Chemical Formula: Mg(OH)2
  • It is composed of a single magnesium (Mg) element joined by 2 Hydroxide (OH and OH) ions. Each ion made of hydroxide is composed of an oxygen atom (O) and one hydrogen atom (H).

The chemical compositions are a reflection of the elements that compose each compound, as well as their molecular structure. Magnesium Oxide is composed of only oxygen and magnesium atoms in contrast to Magnesium Hydroxide contains oxygen, magnesium, and hydrogen atoms creating hydroxide Ions.

Physical Properties

Magnesium Oxide (MgO):

  • appearance: A white, smellless, and tasteless solid usually in the form of crystals or powders.
  • Melting point: The melting temperature is high of around 2,800degC (5,072degF) which makes it suitable for applications with high temperatures.
  • Boiling Point: There is no particular boiling point because it is able to transform directly from a solid and transform into the form of a vapor at extremely high temperatures.
  • Density: It varies based on shape, but usually about 3.58 grams of a cubic centimeter (g/cm3) for the crystal form.
  • Solubility: It is virtually insoluble in water. which indicates the low solubility of aqueous solutions.
  • Odor and taste: Tasteless and odorless.
  • hardness: Magnesium Oxide is rather hard, having a Mohs hardness of around 5.5 up to 6.

Magnesium Hydroxide (Mg(OH)2):

  • Display: A white, crystalline substance or a suspension within water, sometimes called “milk of magnesia.”
  • The melting temperature: The melting temperature is lower when compared with MgO, in the range of 350 to 450 degC (662-842degF).
  • Boiling Point: Similar to MgO, it doesn’t have a distinctive boiling point.
  • Density: Magnesium Hydroxide has generally a smaller density when compared to MgO.
  • Solubility: It has a low solubility when in water, and could form a suspended state when mixed with water.
  • Odor and taste: It is odorless and has a slightly bitter taste when it is consumed in a drug.

Methods of Production

Magnesium Oxide (MgO):

  • The Calcination Process of Magnesite The principal method is heating magnesium (magnesium carbonate) to temperatures that are high about 700-1000degC to make magnesium oxide, as well as release carbon dioxide.
  • Hydrometallurgical Processes This method involves the dissolution of magnesium-containing mineral compounds in sulfuric acid or hydrochloric acid, and then the precipitation of magnesium hydroxide, and then the calcination process until it produces magnesium oxide.
  • Electrochemical reduction: With this technique, the electrolysis process is employed to reduce magnesium sulfate or magnesium chloride to create magnesium metal that can then be further made into magnesium oxide by calcining it.

Magnesium Hydroxide (Mg(OH)2):

  • Precipitation of Magnesium Salts: Magnesium hydroxide can be made by mixing a magnesium salt that is soluble (e.g. magnesium sulfate or magnesium chloride) together with an alkali, such as sodium hydroxide, or ammonium hydroxide. The resultant crystal is known as magnesium hydroxide.
  • Recovery of Brine and Seawater: Magnesium hydroxide is a byproduct of the process of desalinating seawater or by recovering the mineral magnesium in brines.

Difference Between Magnesium Oxide and Magnesium Hydroxide

Here is a comparison chart summarizing the key differences between Magnesium Oxide (MgO) and Magnesium Hydroxide (Mg(OH)2) in terms of various aspects:

Aspect Magnesium Oxide (MgO) Magnesium Hydroxide (Mg(OH)2)
Chemical Formula MgO Mg(OH)2
Appearance White solid White crystalline solid
Melting Point High, around 2,800°C (5,072°F) Lower, around 350-450°C (662-842°F)
Solubility in Water Insoluble Low solubility in water
Production Methods Calcination of magnesite, hydrometallurgical processes, electrochemical reduction Precipitation from soluble magnesium salts, recovery from brine or seawater
Primary Industrial Applications Refractories, electrical insulators, steel production, cement manufacturing, antacids Antacids, laxatives, flame retardants, pH regulation in wastewater treatment
Reactivity with Acids Reacts with acids to form magnesium salts and water Reacts with acids to form magnesium salts and water
Use in Pharmaceuticals Not commonly used in pharmaceuticals Used as an antacid and laxative to treat digestive issues
Environmental Applications Less common in environmental applications Used as a flame retardant in plastics, and in wastewater treatment to neutralize acidic effluents
Health and Safety Considerations Minimal health hazards, and appropriate dust control in industrial settings Minimal health hazards, appropriate dust control in industrial settings, proper dosages when used as a medication

What are the use cases for Magnesium Oxide and Magnesium Hydroxide?

The most common uses of Magnesium Oxide (MgO) and Magnesium Hydroxide (Mg(OH)2) are their application in numerous commercial and industrial applications.

Magnesium Oxide is frequently employed in industries such as metallurgical as an electrical insulator as well as in the manufacture of refractory and cement materials. It is also utilized as an anti-acid in pharmaceuticals.

Magnesium Hydroxide can be found in pharmaceuticals as an anti-acid and laxative used to treat digestive problems. It can be used in ecological applications as a flammable retardant in plastics as well as in the treatment of wastewater for neutralizing acid effluents.

Knowing these usage scenarios is vital to making educated decisions on when and how to utilize these substances effectively.

Uses in Agriculture

Magnesium Oxide (MgO) in Agriculture:

  • pH Adjustment of Soil: Magnesium Oxide can be used to treat soil in order to improve the pH of soils with acidic conditions. It aids in neutralizing the acidity of soil and improves the soil’s capacity to promote the growth of healthy plants. It also helps increase the supply of vital nutrients in the soil.
  • Magnesium as well as Nutrient Supplement The MgO supplement is an important mineral source, which is a vital nutrient to promote the growth of plants. It is added to fertilizers or nutritional blends to guarantee adequate levels of magnesium in the soil. This is vital for photosynthesis as well as the overall health of plants.

Magnesium Hydroxide (Mg(OH)2) in Agriculture:

  • Sol pH adjustment Similar to MgO Magnesium Hydroxide is utilized to improve the pH of soils with acidic conditions by reducing acidity in soils and improving the availability of nutrients. It can be utilized in lieu of lime to adjust pH.
  • Odor Control in the poultry or livestock industry, Mg(OH)2 is used to manage odors and decrease the amount of ammonia released. It aids in maintaining good air quality and creates an environment that is more conducive to animals.
  • Lubricant for Seed Coatings: Magnesium Hydroxide can be utilized as a seed coating to enhance the flowability and lessen the clumping of seeds. This assists in uniform plantation and improves the rate of germination.

Environmental Impact

Magnesium Oxide

  • Production Emissions: The process of producing magnesium oxide by the calcination process of the magnesium carbonate and hydroxide is a high-temperature process. These processes could produce CO2 (CO2) as well as other greenhouse gases that contribute to carbon footprints. This is especially true when fossil fuels are utilized to produce the required heat.
  • Resource Intensity: The extraction and processing of magnesium carbonate as well as other materials that are required to start magnesium oxide production could be resource-intensive, and can affect the use of land and energy consumption.
  • Waste Disposal: The waste produced during the manufacturing process comprising unreacted materials as well as used refractory materials, could need proper disposal and management.

Magnesium Hydroxide

  • Emissions Reduction: In certain applications, magnesium hydroxide may have better environmental benefits. For example, when it is employed as a flame retardant, it may aid in lessening the environmental impacts of fires, as well as limit the amount of air pollution.
  • energy efficiency: Producing magnesium hydroxide by precipitation reactions is usually lower in energy consumption compared to calcination processes employed for manufacturing magnesium oxide.
  • Wastewater Treatment: Magnesium hydroxide can be used in wastewater treatment processes to regulate the pH of water and eliminate impurities. This process can aid in lessening the environmental effects of industrial discharges of wastewater.
  • Recyclability: There are instances where magnesium hydroxide may be recycled, which makes it a sustainable option when reusing the substance is possible.

Health and Safety Considerations

Magnesium Oxide (MgO):

  • Health Risks Magnesium Oxide is generally considered to be safe for the majority of applications. Exposure to airborne fine particles during the manufacturing process could possibly cause irritation to the eyes, skin, and respiratory system.
  • Safety Tips: When handling MgO in industrial settings, it’s crucial to follow the appropriate safety precautions. This includes wearing Personal Protective Equipment (PPE) like goggles, gloves, and respiratory protection in order to limit exposure to inhalation and contact. Proper ventilation and dust-control precautions should be taken to minimize the danger of breathing in dust particles that are in the air.

Magnesium Hydroxide (Mg(OH)2):

  • Health Risks: Magnesium Hydroxide is safe for the majority of uses particularly for environmental and pharmaceutical uses. In pharmaceuticals, it’s considered safe if taken according to the directions.
  • Safety precautions: When handling Mg(OH)2 in industrial processes, the same precautions for the control of dust and respiratory protection are to be followed. If it is used as a medicine to treat a condition, it must be administered according to the recommended amounts and dosage guidelines, in order to avoid excessive use or any potential adverse unwanted side adverse effects.


Magnesium Oxide (MgO) and Magnesium Hydroxide (Mg(OH)2) Are two different inorganic compounds that have various properties and applications. MgO is a very hot white solid that has minimal solubility in water.

It’s commonly used in industry for its refractory properties, as well as its electrical insulating properties. On the other hand, Mg(OH)2 is a lower melting white solid that is used often in pharmaceuticals as an antiacid and laxative as well as in environmental engineering to aid water treatment due to the pH regulating qualities it has.

Both substances interact with acid to produce magnesium salts as well as water. Mg(OH)2 is typically associated with environmental and medicinal applications.

Knowing the differences between these two compounds is crucial to making educated choices regarding their diverse healthcare and industrial applications.

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