Difference Between Magnesium Oxide and Magnesium Citrate

Main Difference – Magnesium Oxide vs Magnesium Citrate

Magnesium is an alkaline earth metal that is in the group 2 of the periodic table of elements. It can form many basic compounds. Magnesium often forms ionic compounds by forming the magnesium divalent cation. Magnesium oxide is one such ionic compound. It is a white solid. Magnesium Citrate is a complex compound that is the magnesium salt of the citric acid. It is used as a magnesium supplement. The main difference between magnesium oxide and magnesium citrate is that magnesium oxide in an ionic compound whereas magnesium citrate is a salt of magnesium.

Key Areas Covered

1. What is Magnesium Oxide
     – Definition, Chemical Properties
2. What is Magnesium Citrate
    – Definition, Chemical Properties and Uses
3. What is the Difference Between Magnesium Oxide and Magnesium Citrate
    – Comparison of Key Differences

Key Terms: Citric Acid, Hygroscopic, Ionic, Magnesium, Citrate, Magnesium Oxide, Salt

What is Magnesium Oxide

Magnesium Oxide is an inorganic compound that has the chemical formula MgO. The molar mass of this compound is 40.304 g/mol. It is a white powder that is hygroscopic. This means it can absorb water from the air when exposed to the atmosphere.

Magnesium oxide is odorless and has a boiling point of 3600^oC. The melting point of this compound is about 2800^oC. A saturated solution of magnesium oxide has a pH value of 10.3. Therefore, it is a basic compound.

Figure 1: Physical Appearance of Magnesium Oxide

Magnesium oxide is an ionic compound composed of magnesium ions and oxide ions in a lattice. There are ionic bonds in between cations and anions. When this compound is added to water, it forms magnesium hydroxide. But when magnesium hydroxide is heated, it gives magnesium oxide again. Magnesium oxide can be produced by calcination of magnesium carbonate or magnesium hydroxide.

What is Magnesium Citrate

Magnesium citrate is a magnesium salt of citric acid, having the chemical formula C₆H₆MgO₇. The molar mass of this compound 214.41 g/mol. The IUPAC name of magnesium citrate is Magnesium 2-hydroxypropane-1,2,3-tricarboxylate. Magnesium citrate is available as a white powder.

Magnesium citrate contains one magnesium cation per citrate anion. But sometimes, other magnesium salts such as trimagnesium citrate also are called magnesium citrate; hence it is a common name. However, magnesium citrate (containing one magnesium cation) is more water soluble than other magnesium citrate salts and is less alkaline.

Figure 2: Chemical Structure of Magnesium Citrate

There are many different applications of magnesium citrate in different areas. For example, magnesium citrate is a food additive that is used to regulate the acidity of food items. In medicine, it is used as saline laxative (a substance used to loosen stools, and avoid constipation). Apart from that, it is used as a dietary supplement because it contains about 11.23% magnesium by weight. It is available in pill form when used as a dietary supplement.

Difference Between Magnesium Oxide and Magnesium Citrate

Definition

Magnesium Oxide: Magnesium Oxide is an inorganic compound that has the chemical formula MgO.

Magnesium Citrate: Magnesium citrate is a magnesium salt of citric acid having the chemical formula C₆H₆MgO₇.

Molar Mass

Magnesium Oxide: The molar mass of Magnesium Oxide is 40.304 g/mol.

Magnesium Citrate: The molar mass of Magnesium citrate is 214.41 g/mol.

Hygroscopy

Magnesium Oxide: Magnesium Oxide is highly hygroscopic.

Magnesium Citrate: Magnesium citrate is less hygroscopic.

Alkalinity

Magnesium Oxide: Magnesium Oxide is highly alkaline.

Magnesium Citrate: Magnesium citrate is less alkaline.

Nature

Magnesium Oxide: Magnesium Oxide is an ionic compound.

Magnesium Citrate: Magnesium citrate is a magnesium salt of citric acid.

Conclusion

Magnesium oxide and magnesium citrate are inorganic compounds that are used as magnesium supplements. But they are different from each other due the chemical structure and physical properties. The main difference between magnesium oxide and magnesium citrate is that magnesium oxide in an ionic compound whereas magnesium citrate is a salt of magnesium.

Reference:

1. “MAGNESIUM CITRATE.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.
2. “Magnesium oxide.” Wikipedia, Wikimedia Foundation, 6 Jan. 2018, Available here.
3. “MAGNESIUM CITRATE.” MAGNESIUM CITRATE | 144-23-0, Available here.

Image Courtesy:

1. “Magnesium oxide” By Walkerma assumed -Own work assumed (based on copyright claims) (Public Domain) via Commons Wikimedia
2. “Magnesium citrate” By Edgar181 – Own work (Public Domain) via Commons Wikimedia