Magnesium Chloride

An Overall Study of Magnesium Chloride

Since you have started studying chemistry, you are aware of both of these chemical elements called magnesium and chlorine. These two minerals are equally important for various functions in a human body as well as other commercial needs. Magnesium or Mg and chlorine or Cl combine to form magnesium chloride. 

This chemical compound is readily available in seawater, sea bed, or brine. This mineral can also be extracted by the process solution mining and evaporation of seawater. Hydrated MgCl2 is mostly abundant in nature; however, the large-scale production of magnesium metal occurs from the anhydrous form of magnesium chloride.

From the below content, you can learn the structure, property, preparation, and usages of this compound. 

Magnesium Chloride

MgCl2 suggests magnesium chloride chemical formula in chemistry. Some other chemical name of this salt is magnesium dichloride, chloromagnesite, and magnesium (II) chloride. One magnesium – Mg+2 and two ions of chloride Cl- form magnesium chloride.

Chloromagnesite and all its salts belong to ionic halides group with a whitish-grey granule appearance. This compound is utilised in medicine and regarded as a high source of Mg ions, a vital component for various cellular activities. 

Physical Properties

  • Colour – White, light grey, colourless.

  • Structure – Granule, crystalline.

  • Geometrical structure – Octahedral with 6-coordination point.

  • State – Solid at standard temperature.

  • Water-solubility – Extremely high.

  • Solubility – Ethanol, also partially soluble in pyridine and acetone.

  • Odour – Odourless.

Chemical Properties

Magnesium chloride formula

MgCl2 (Anhydrous), MgCl2 * 6H2O (Hexahydrate)

MgCl2 molecular weight (g / mol)

95.211 gram per mole (Anhydrous), 203.31 gram per mole (Hexahydrate)

Density of MgCl2

2.32 gram per cm3 (Anhydrous), 1.569 gram per cm3 (Hexahydrate)

Magnesium chloride melting point

714oC, 987 K, 1317oF

117oC, 390 K, 243oF (Hexahydrate)

Magnesium chloride boiling point

1412oC, 1685 K, 2574oF

Water solubility 

For anhydrous 

52.9 gram per 100 ml water at 0oC

54.3 gram per 100 ml water at 20oC

72.6 gram per 100 ml water at 100oC

For hexahydrate

235 gram per 100 ml water at 20oC

Flashpoint of magnesium chloride


Structure of Magnesium Chloride

Magnesium chloride has a crystalline structure. The positively charged magnesium ion - Mg+2 and negatively charged chlorine ions Cl- create the ionic bond by attracting each other. And, magnesium chloride formation occurs by transferring electrons of the outer orbits.

This ionic bond helps to complete the electron transferring process between atoms. Magnesium chloride solution can conduct electricity due to its electrolytic nature. In its solid state at room temperature, every anion is encircled by cations and vice versa. One magnesium cation holds 2+ charge and one chlorine anion holds 1- charge. However, like a compound, magnesium chloride is neutral. So, magnesium ion forms the ionic bond with two chlorine ions.

Thus, the ratio of magnesium ion : chloride ion is 1 : 2 and the simplest magnesium chloride chemical formula is MgCl2. Look at the following diagram of the magnesium chloride structure to understand their chemical and molecular bonding.

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Preparation of Magnesium Chloride

Due to various usages in different industrial and commercial purposes, this ionic salt is produced in large amounts. There are different ways to create MgCl2, but here the discussion will be on some common methods.

In hexahydrate state, the magnesium ion is octahedral; however, it coordinates with 6 water ligands. The heating process of magnesium chloride hexahydrate is not straightforward. The hydrous form of this salt is heated along with alcohol and gradually distilled off the H2O. This way, anhydrous MgCl2 is extracted from its hydrous state.

Magnesium chloride in its anhydrous form is generated by heating hexamine-complex chloride salt as well. The most preferred method of anhydrous magnesium chloride preparation is the chemical reaction between magnesium and mercury (II) chloride.

Mg + HgCl2 🡪 MgCl2 + Hg

Another most common method of producing MgCl2 is by Dow process. In this process, magnesium hydroxide reacts with hydrochloric acid and form magnesium chloride and water. Following is the chemical formula of this reaction-

Mg(OH)2 (s) + 2 HCl (aq) 🡪 MgCl2 (aq) + 2 H2O (l)

Magnesium carbonate can substitute magnesium hydroxide in a similar reaction. However, as a by-product, carbon dioxide will also be produced along with water. Here is the chemical formula-

MgCO3 (s) + 2 HCl (aq) 🡪 MgCl2 (aq) + CO2 (g) + 2 H2O (l)

Another alternative way to produce MgCl2 is by the chemical reaction between aluminium chloride and magnesium with aluminium as a by-product.

3 Mg (s) + 2 AlCl3 (aq) 🡪 3 MgCl2 (aq) + 2 Al (s)

Other Important Reactions

For your all upcoming examinations, you need to learn some essential reactions of magnesium chloride. If you can check previous question papers of your board exam, NEET, JEE, etc., you will come across some MgCl2 reactions repetitively.

  • Silicon Tetrachloride and Magnesium

In this reaction, magnesium chloride and silicon are produced.

SiCl4 (l) + 2 Mg (s) 🡪 Si (s) + 2 MgCl2 (s)

  • Titanium Tetrachloride and Magnesium

At the end of this chemical reaction, titanium and magnesium chloride are generated.

TiCl4 (g) + 2 Mg (l) 🡪 Ti (s) + 2 MgCl2 (l) 

  • Magnesium and Hydrochloric Acid 

It is one of the most common reactions of MgCl2, where the by-product is hydrogen.

Mg (s) + 2 HCl (aq) 🡪 MgCl2 (aq) + H2 (g)

  • Magnesium Bicarbonate and Hydrochloric Acid

3 Mg(HCO3)2 (l) + HCl (l) 🡪 MgCl2 (aq) + H2O (l) + CO2 (g)

  • s - Solid

  • g – Gas

  • l – Liquid

  • aq – Aqueous solution


  1. What type of Bond is Found in Magnesium Chloride Atoms?

  1. Polar covalent

  2. Covalent

  3. Ionic bond

  4. None of the above

  1. How many water molecules can be coordinated by one magnesium chloride hexahydrate?

  1. 8

  2. 6

  3. 4

  4. 2

  1. Where is MgCl2 (natural) found the most?

  1. North America

  2. South America

  3. Brazil

  4. Canada

  1. What percentage of elemental magnesium mass is found in anhydrous MgCl2?

  1. 30.2%

  2. 28.4%

  3. 26.2%

  4. 25.5%

  1. What will come in the blank?

MgCO3 (s) + 2 HCl (aq) 🡪 MgCl2 (aq) + ___ + 2 H2O (l)

  1. CO3

  2. CO

  3. CO2

  4. C2


  1. c. Due to the ionic bond of magnesium ion and chlorine ion, magnesium chloride forms.

  2. b. One hexahydrate magnesium chloride coordinates with six water molecules.

  3. a. In North America, MgCl2 is naturally abundant in the largest amount.

  4. d. 25.5% of the elemental mass of magnesium is found in anhydrous magnesium chloride.

  5. c. CO2.

Uses of Magnesium Chloride

MgCl2 is found in various medicines to prevent or treat magnesium deficiency in human bodies. Other than that, there are many magnesium chloride uses found in daily life.

  • A Precursor to Magnesium Metal

Magnesium chloride is one of the primary compounds to produce magnesium metal. This reaction is accomplished by electrolysis.

MgCl2 🡪 Mg + Cl2

This method of magnesium production occurs on a large scale industrially.

  • Erosion and Dust Control

This ionic salt is one of the most important components used to control dust, wind erosion, and soil stabilisation. However, there are both positive and negative impacts of applying magnesium chloride to bare soil and roads.

  • Ice Control

The use of MgCl2 is also found in de-icing parking lots, sidewalks, and highways in low-temperature areas. Places that are typically struck by extreme snowstorms use magnesium chloride to treat the icy conditions of various transport ways. As a prevention to ice control, anti-icing process is practised. Nonetheless, there are some other processes like pre-wetting and pre-treating to clear the show and ice bonds off the roadways.

  • Catalyst Support

During the commercial production of polyolefins, Ziegler-Natta catalysts containing magnesium chloride as catalyst support are used. MgCl2 helps to develop high quality stereospecific catalysts for commercial purposes.

  • Cuisine

This salt is mostly found in Japanese and Chinese cuisine. Tofu, a preparation from soya milk, contains a high amount of magnesium chloride. This preparation is one of the major dishes in these cuisines.

  • Nutrition

MgCl2 is also present in various nutraceutical products like diet supplements, food additives, etc. Furthermore, this chemical compound is also available in different pharmaceutical preparations, such as medication. It treats blood pressure, diabetics, heart diseases, eclampsia, acid indigestion and other illness. 

  • Horticulture

Similar to the human body, plants also need magnesium for their cellular activities. Magnesium chloride flakes are effectively used as an alternative of Epsom salt or magnesium sulfate in horticulture or gardening. However, the recommended amount of MgCl2 is always lower than magnesium sulfate. This is because of the presence of chlorine in MgCl2, and an excess amount of chlorine can be toxic for plants.

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FAQ (Frequently Asked Questions)

1. What is the way to consume magnesium chloride flakes?

Ans. It is advised to consume magnesium chloride as per the recommendation of doctors. However, it should be known that oral consumption of MgCl2 can create laxative effects.

2. What can be the side effects of MgCl2?

Ans. MgCl2 can cause various side effects like flushing, respiratory depression, sweating, considerable reduction of blood pressure, hypothermia, stupor, etc.

3. What are the primary benefits of consuming magnesium chloride as per doctor’s recommendation?

Ans. It is used as a mineral supplement to treat magnesium deficiency in the body. This can also help to prevent excessive secretion of stomach acid.

4. What is the neurotic benefit of MgCl2?

Ans. MgCl2 is considered as a natural relaxer of muscles. Hence, the use of magnesium chloride helps to deal with anxiety. It acts as a relaxant of the nervous system to make an individual calm.