Magnesium Chloride(MgCl2) Properties(25 Helpful Facts)

MgCl2is a halogenated complex of magnesium with two Chlorine atoms. Let us discuss some more facts about MgCl2 in this article.

MgCl2 is also known as chloromagnestite. MgCl2 is highly hygroscopic. MgCl2 is electrolytic as it conducts electricity in the molten state. MgCl2 is prepared using the Dow Process which uses Magnesium Hydroxide and Hydrochloric acid to produce MgCl2. MgCl2 is naturally extracted from brine or seawater.

The following article will discuss some more basic facts about MgCl2, like the IUPAC name, molar mass, molar density, melting point, and crystal structure.

MgCl2 IUPAC Name

The IUPAC name of MgCl2 is Magnesium Dichloride.

MgCl2 Chemical Formula

The chemical formula for Magnesium Chloride is MgCl2. The atomic symbol for Magnesium is Mg, and for chloride, it is Cl. The ratio of Magnesium ion and Chloride ion in MgCl2 is 1:2.

MgCl2 CAS Number

7786-30-3 is the CAS number of Magnesium Chloride.

MgCl2 Chemspider ID

22987 is the Chemspider ID of Magnesium Chloride.

MgCl2 Chemical Classification

Magnesium Chloride can be classified as follows-

  • MgCl2 is an ionic compound.
  • MgCl2 is an inorganic magnesium salt.
  • MgCl2 is an inorganic chloride.
  • MgCl2 is a magnesium halide.
  • MgCl2 is a lewis acid.

MgCl2 Molar Mass

The molar mass of MgCl2 is 95.211 g/mol. The compound consists of one magnesium cation with an atomic mass of 24.305u, and the atomic mass for chloride is 35.453 g/mol. The total molar mass is calculated by adding the mass of one magnesium ion and two chlorides on ions i,e; 24.305 + (2*35.453) = 95.211 g/mol.

MgCl2 Color

The color of MgCl2 is white or colorless.

MgCl2 Viscosity

The viscosity of MgCl2 is 7.0 centiPoise. Viscosity is the measure of resistance in a liquid that restricts itself from changing its shape or resistance to flow.

MgCl2 Molar Density

The molar density of MgCl2 is 0.0243 mol/cm3, and the density of MgCl2 is 2.32 g/cm3. To calculate the molar density, the density is divided by the molar mass as 2.32/95.211 = 0.243 mol/cm3.

MgCl2 Melting Point

The melting point of MgCl2 is 714o C or 1,317o F or 987 K. The melting point of MgCl2 is extremely high due to its crystalline structure and strong ionic forces, which bind the atoms very strongly with each other.

MgCl2 Boiling Point

The boiling point of MgCl2 is 1,412o C or 2,574o F, or 1,685 K. High boiling point of MgCl2 is due to the fact that there exists strong ionic bonding in the crystal structure.

MgCl2 State At Room Temperature

MgCl2 exists as a crystalline solid at room temperature as the melting and boiling points of the crystal are above 500o C. The ionic bonds are so strong that it remains in the solid form at room temperature as it requires a lot of energy to break these bonds.

MgCl2 Ionic Bond

The MgCl2 compound consists of two ionic bonds. Both the chloride ions share charges with the central magnesium metal and form two ionic bonds as they are oppositely charged. Magnesium ions donate their two electrons to two chloride ions, and bond formation occurs.

Bonding in MgCl2

MgCl2 Ionic Radius

The ionic radius of the Mg-Cl bond in the MgCl2 structure is 2.53 Ao. Ionic radius is calculated for those compounds in which bond formation occurs based on charged ions. Atoms donate and accept electrons, and thus the formation of ionic bonds takes place.

MgCl2 Electronic Configurations

The electronic configuration describes the system of distribution of electrons in the shells of an atom. Let us have a look at the electronic configuration of MgCl2 in detail.

The electronic configuration of Mg and Cl is [Ne]3s2 and [Ne]3s2 3p5, respectively. Magnesium ion contains 2 valence electrons, and chloride ion contains 7 valence electrons. Each chloride ion contains three lone pairs and one bond pair and while each magnesium ion consists of only two bonding electrons.

MgCl2 Oxidation State

The oxidation state of magnesium ions in MgCl2 is +2, while the oxidation state of two chloride ions is -1. The magnesium ions donate one electron each to two chloride ions and gain a +2 charge. While the chloride ions accept an electron from the magnesium ion and acquire a -1 charge.

MgCl2 Acidity

MgCl2 is weakly acidic as it is formed with the reaction of a weak base, magnesium hydroxide, and strong acid, hydrochloric acid. The two chloride ions pull out the electron density from the magnesium ions, and hence it can accept electrons due to the electropositive nature.

Is MgCl2 Odourless?

MgCl2 is an odorless solid compound.

Is MgCl2 Paramagnetic?

Paramagnetism is a property of such compounds, metals, or ions which contain unpaired electrons in their valence shell. Let us discuss if MgCl2 is paramagnetic or not.

MgCl2 is non-paramagnetic as it does not contain any unpaired electrons. The valence shell of magnesium consists of two paired electrons donated to form ionic bonds with two chloride ions, and the valence shell of magnesium becomes empty.

MgCl2 Hydrates

MgCl2 exists in several hydrated forms. The melting and boiling points of these MgCl2 hydrates are slightly lower than the anhydrous form of MgCl2.

The hydrates of Magnesium chloride are –

  • Magnesium Chloride Monohydrate (MgCl2.H2O)
  • Magnesium Chloride Hexahydrate(MgCl2.6H2O)
  • Magnesium Chloride Octahydrate(MgCl2.8H2O)

MgCl2 Crystal Structure

MgCl2 is present in CdCl2 crystal structure form in nature. The ions are hexagonally coordinated and have octahedral geometry with magnesium ions at the center. The lattice parameters of this structure are a=3.68Ao, b=3.68Ao,c=6.42Ao,α=90o, β=90o, and ɣ=120o. The MgCl2 structure exists in layered 2D form.

MgCl2 Polarity and Conductivity

  • MgCl2 is a polar molecule. The molecular geometry of MgCl2 is bent. The direction of the dipole is from Mg+2 to Cl.
  • MgCl2 conducts electricity in a liquid or molten state only. MgCl2 is highly soluble in water. In the liquid state, the compound dissociates into ions and conducts electricity.

MgCl2 Reaction With Acid

MgCl2 is an acid, and though weak, its reaction with acid is not much pronounced. For example, the reaction of MgCl2 with acetic acid(CH3COOH) gives magnesium acetate(Mg(CH3COO)2) and hydrochloric acid(HCl).

MgCl2 + 2CH3COOH = Mg(CH3COO)2 + 2HCl

MgCl2 Reaction With Base

When MgCl2 reacts with a base like sodium hydroxide(NaOH) to produce a white precipitate of magnesium hydroxide(Mg(OH)2 )and sodium chloride(NaCl) salt.

MgCl2 (aq) + NaOH (aq) = Mg(OH)2 (s) + NaCl (aq)

MgCl2 Reaction With Oxide

MgCl2 reacts with a number of oxides to form magnesium oxide and corresponding salt. For example, when MgCl2 reacts with sodium oxide(Na2O), it produces magnesium oxide and sodium chloride salt.

MgCl2 + Na2O = MgO + NaCl

MgCl2 Reaction With Metal

MgCl2 reacts with those metals which have higher reactivity than magnesium in the metal activity series. MgCl2 does not react with iron, zinc, and copper as magnesium has higher reactivity than these metals.

MgCl2 + Cu = No Reaction


MgCl2 exists in granular form and is a very vital source of magnesium in cellular activities. MgCl2 is used as a catalyst in some reactions and in the prevention of rusting of iron. MgCl2 is used in several diet supplements as magnesium is very helpful for the human body. MgCl2 plays a vital role in plant growth.

Scroll to Top