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Magnesium Sulfate Formula

Last updated date: 23rd May 2024
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What is the Formula of Magnesium Sulphate?

Magnesium sulphate salt also known as epsom salts. Magnesium sulphate is an inorganic salt that contain magnesium and sulphate.The formula of magnesium sulphate is a MgSO4 that contains magnesium cations Mg+2 (20.19 percent by mass) and sulphate anions SO4-2. It is a white crystalline substance that is water soluble but not ethanol soluble.

Chemical Elements Present in the Formula of Magnesium Sulphate

The chemical formula of magnesium sulphate includes magnesium (Mg), sulphur (S), and oxygen (O) elements in it. These elements are present in an ionic form.

Magnesium Sulphate Formula Structure

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The structure of the formula of magnesium sulphate is shown above, from this you can see that the sulphate ion is bonded with an ionic bond with the magnesium. This ionic bond is a kind of strong electrostatic attractive force that is acting between the magnesium ion and sulphate ion.

What is the Formula for Magnesium Sulphate in Hydrated Form?

Magnesium sulphate is commonly found in the form of a hydrate, the molecular formula of magnesium sulphate in hydrated form is MgSO4.nH2O, with n values ranging from 1 to 11. The heptahydrate MgSO4 H2O, sometimes known as Epsom salt, is a household compound with several traditional uses, including bath salts.

Magnesium sulphate is mostly used in agriculture to alleviate magnesium deficiency in soils (an essential plant nutrient). This application favours monohydrate, which was producing 2.3 million tonnes per year by the mid-1970s. The salt is a considerable component of the water from several springs, and the anhydrous form and many hydrates occur in nature as minerals.

Epsom salt gets its name from a bitter saline spring in Epsom, Surrey, England, where the salt was made from springs that arose where the porous chalk of the North Downs met the nonporous London clay. To generate the hexahydrate, the heptahydrate easily loses one equivalent of water. It is a natural source of magnesium as well as sulphur. Bath salts, exfoliants, muscle relaxants, and pain medications all contain epsom salts. These are not the same as Epsom salts for gardening, as they contain smells and perfumes that are not good for plants.

Magnesium sulphates are ubiquitous minerals found in the earth's crust. The majority of their occurrences are linked to supergene processes. Some of them are also key components of deposits of evaporitic potassium-magnesium (K-Mg) salts. The Dawn Spacecraft discovered bright spots in Occator Crater on the dwarf planet Ceres that are most likely reflected light from magnesium sulphate hexahydrate.

Magnesium Sulphate as a Mineral

MgSO4 hydrates are found in almost all known mineralogical forms. The natural analogue of "Epsom salt" is epsomite. Meridianiite,MgSO4. 11H2O, has been found on the surface of frozen lakes, and it is thought to exist on Mars as well. The next lower hydrate is hexahydrite. Pentahydrite, starkeyite, and, especially, sanderite, the next three lower hydrates—are uncommon. Kieserite is a monohydrate that is found in evaporite deposits in large quantities. Some burning coal dumps have been found to contain anhydrous magnesium sulphate.


Magnesium sulphate is commonly sourced from dry lake bottoms and other natural sources. It can also be made by mixing sulfuric acid with magnesite (magnesium carbonate,MgCO3) or magnesia (oxide, MgO).

Another option is to treat seawater or industrial wastes containing magnesium to precipitate magnesium hydroxide and then react the precipitate with sulfuric acid.

Properties of Magnesium Sulphate

The principal mechanism that causes sound absorption in saltwater at frequencies above 10 kHz is magnesium sulphate relaxation (acoustic energy is converted to thermal energy). Because lower frequencies are absorbed less by the salt, low frequency sound travels further in the ocean. Boric acid and magnesium carbonate help in absorption as well.

Uses of Magnesium Sulphate

Medical - Magnesium sulphate is used both physically and orally (as Epsom salt).

The formulation as bath salts is the most common external usage, notably for soothing painful feet in foot baths. Such baths have also been claimed to help with muscle discomfort, soreness, and injury healing.

These assertions, however, have not been empirically validated. The salt's major effect is cosmetic: it minimises skin wrinkling caused by prolonged immersion in plain water. It is also a common component of the isolation tank solution.

Agriculture- Magnesium sulphate is used in agriculture to raise the magnesium or sulphur content of the soil. It's usually used on potted plants or magnesium-deficient plants including potatoes, tomatoes, carrots, peppers, lemons, and roses. The high solubility of magnesium sulphate, in comparison to other magnesium soil additives (such as dolomitic lime), enables for foliar feeding. Magnesium sulphate solutions are also almost pH neutral when compared to alkaline magnesium compounds such as those found in limestone; thus, using magnesium sulphate as a magnesium source for soil does not appreciably alter soil pH. 

Food Preparation- Magnesium sulphate is a brewing salt used in the production of beer. It can also be used to make tofu as a coagulant.

Construction - Magnesium sulphate is used to make particular cements by reacting magnesium oxide with magnesium sulphate solution, and these cements have a better binding ability and resilience than Portland cement. This cement is primarily used to create lightweight insulating panels. Its use is restricted due to a lack of water resistance.

When there are no service records of the material exposed to actual weathering circumstances, magnesium (or sodium) sulphate is also used to test aggregates for soundness in line with the ASTM C88 standard. The test is carried out by repeatedly immersing the sample in saturated solutions and then drying it in the oven to remove the salt that has accumulated in permeable pore spaces. The internal expansive force, which is produced from the salt's rehydration after re-immersion, mimics the expansion of water when it freezes.

Did You Know?

  • For many years magnesium was thought to be the same element as calcium. 

  • Magnesium fire is very difficult to put out as it can burn in nitrogen, carbon dioxide, and water.

FAQs on Magnesium Sulfate Formula

Question1: What is the Use of Magnesium Sulphate in Aquaria?

Answer: Magnesium sulphate heptahydrate is also used to keep magnesium levels stable in marine aquariums with a lot of stony corals, as it is steadily depleted during the calcification process.Calcium and alkalinity concentrations are difficult to control in a magnesium-deficient marine aquarium because there isn't enough magnesium to stabilise these ions in the saltwater and prevent their spontaneous precipitation into calcium carbonate.

Question2: What are the Characteristics of Magnesium Sulphate Salt?

Answer: Magnesium sulphate (MgSO4) is an inorganic salt with the chemical formula MgSO4. Sulfuric acid magnesium salt or Magnesium sulphate anhydrous are other names for it. Epsom salt is the common name for it. Magnesium sulphate is a crystalline, odourless substance with a white colour.