Properties of Magnesium Sulfate

Magnesium sulfate is a compound with many properties and uses. It is a type of salt as well as a mineral which is widely found in the geological environment. It is obtained from the ore, epsomite, a white solid substance found on the surface of the earth. Besides, it is also found in oceans and springs. This amazing chemical compound formed by magnesium and sulfate is represented by the molecular formula MgSO₄.

Commercially, it is produced by dissolving magnesium carbonate in hot, dilute sulfuric acid. The product, thus obtained, is magnesium sulfate heptahydrate. The prefix "hepta" refers to the seven molecules of water which are loosely bound to each of the magnesium sulfate molecules. Magnesium sulfate heptahydrate (MgSO₄.7H2O) is commonly known as epsom salt.

Physical Properties of Magnesium Sulfate

• Physical State: Magnesium sulfate is a colorless, odorless substance with fine needle-like structures.
• Taste: It is slightly bitter in taste.
• Solubility: It is highly soluble in inorganic solvents like water. At room temperature, around 700 grams of magnesium gets dissolved in one liter of water. It is partially soluble in organic solvents, like glycerin and alcohol.
• Hygroscopy: Magnesium sulfate in its anhydrous form, is hygroscopic. It has a tendency to attract moisture from the air easily. Due to this property, it is often used as a drying agent in organic synthesis.
• Sound Absorption: Magnesium sulfate has the ability to convert acoustic energy into heat energy. In sea water, magnesium is mainly responsible for the absorption of sound. It mainly affects sound of higher frequencies.

Chemical Properties of Magnesium Sulfate

• Hydrates: Magnesium is found in various types of hydrates, other than heptahydrate. It also forms hexahydrate (6), pentahydrate (5), starkeyite (4) and sanderite (2). But the occurrence of these is rare. Kieserite is the monhydrate form, which is obtained in evaporitic deposits of seawater.
• pH Scale: Magnesium sulfate solution is neither acidic nor basic. On a pH scale, its value is around 6.0.
• On heating: When heated at 250ºC, heptahydrate loses water to form anhydrous salt. On further heating, the salt is partially broken down to magnesium oxide.
• Reaction with Water: When dissolved in water, magnesium sulfate splits into ions of magnesium and sulfate.

Medicinal Properties of Magnesium Sulfate

Magnesium sulfate has some therapeutic properties too. Due to its cathartic properties, it can be used when needed as a laxative to evacuate the bowel. Applying magnesium paste on boils help in the drainage and healing of boils. In flotation therapy, magnesium sulfate is used as a bath salt. Here, the high concentration of salt raises the specific gravity of bath water, which makes the body buoyant and helps it to relax.

Magnesium sulfate has huge demand in various industries because of its versatility. Some of the key uses of magnesium sulfate are, as protein coagulant for food products, leather tanning agent in leather industry, fireproof agent, dyeing agent, salt agent, and plastic stabilizers.