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The Physical Properties of Magnesium Oxide

author image N.C. Hinkson
N.C. Hinkson has been writing since 2008. She has previously published in the "Journal of Applied Toxicology." Hinkson holds a Bachelor of Science in cell and molecular biology from the University of Toronto and a Master of Science in biology from Tennessee State University.
The Physical Properties of Magnesium Oxide
Spoon of antacid above a glass of water Photo Credit: Alena Dvorakova/iStock/Getty Images

Magnesium oxide, also known as magnesia, is a naturally occurring compound found in metamorphic rocks. The chemical formula of magnesium oxide is MgO, meaning it contains a magnesium atom and an oxygen atom, forming an ionic bond. Magnesium oxide has a wide range of uses and can be found in a number of household and industrial items including antacids, laxatives and dietary supplements.

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Magnesium oxide is hygroscopic. Hygroscopic substances absorb water molecules spontaneously when exposed to air. A familiar compound that exhibits this property is sugar. Magnesium oxide's physical state at room temperature is a white, odorless powder.

pH and Solubility

Magnesium oxide has a high pH of 10.3, meaning it is very basic. This makes it a great antacid since it can neutralize stomach acid in an upset stomach. Magnesium oxide is slightly soluble in water at 0.0086 g of powder per 100 mL of water.

Melting Point and Boiling Point

This compound has an extremely high melting point at 5,072 degrees Fahrenheit and a high boiling point at 6,512 degrees Fahrenheit.

Safety Information

Magnesium oxide is noncombustible and is a relatively safe chemical with a National Fire Protection Association rating of 1. Exposure to magnesium oxide can have some potential side effects including eye irritation and nose irritation. If you inhale it, go out to get fresh air. Rinse your eyes if you make contact with magnesium oxide, and wear eye protection and protective clothing if you handle it.

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