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Magnesium bromide

Magnesium bromide

Last updated: March 19, 2023

Magnesium bromide is an inorganic compound with formula MgBr₂.

Table of contents

Names

List of substance names

Nomenclature

Name

Typical name: Magnesium bromide

Compositional nomenclature: Magnesium bromide; Magnesium dibromide

Formulae and structures

List of formulae

Formula name

Formula

Typical formula: MgBr₂

Compositional formula: MgBr₂

Structural formula

Lewis structure

Colored Lewis structure

Properties

List of substance properties

Item

Value

Name: Magnesium bromide

Formula: MgBr₂

Appearance: Colorless solid

Odor: Odorless

Molar mass: 184.113 g/mol

Density: 3.722 g/cm³^[1]
Solid

Melting point: 711 °C^[1]

Boiling point: 1158 °C^[1]

Constituents

Constituent ions

Ion	Name	Charge number	Number
Mg²⁺	Magnesium ion	2	1
Br⁻	Bromide ion	-1	2

Constituent atoms

Atom	Name	Oxidation state	Number
Mg	Magnesium	+2	1
Br	Bromine	−1	2

Ratio of atoms

Atom	Atomic weight	Number	Atomic ratio	Weight ratio
Mg	24.305	1	33.33%	13.20%
Br	79.904	2	66.67%	86.80%

Thermodynamic properties

Phase transition properties

Item

Value

Enthalpy of fusion: 39.3 kJ · mol⁻¹^[1][2]
at 711°C

Enthalpy of vaporization: 149 kJ · mol⁻¹^[1]
at 1158°C

Enthalpy of vaporization at 25°C: 222 kJ · mol⁻¹^[1]

Enthalpy of other transition: –

Standard thermodynamic properties

State	Standard enthalpy of formation Δ_fH° kJ · mol⁻¹	Standard Gibbs energy of formation Δ_fG° kJ · mol⁻¹	Standard molar entropy S° J · K⁻¹ · mol⁻¹	Standard molar heat capacity at constant pressure C_p° J · K⁻¹ · mol⁻¹
Crystalline solid	−524.3^[3]	−503.8^[3]	117.2^[3]	–
Gas	−309.6^[3]	–	–	–
Ionized aqueous solution	−709.94^[3]	−662.7^[3]	26.8^[3]	–
Crystalline solid 6 hydrate	−2410.0^[3]	−2055.7^[3]	397.^[3]	–

Solubility

Qualitative solubility

Reactive

Miscible

Very soluble: H₂OWater

Soluble

Slightly soluble

Very slightly soluble

Insoluble

Solubility in water (g/100 g)^[1]

0°C	10°C	20°C	30°C	40°C	60°C	100°C
98	99	101	104	106	112	125

Solubility in water (g/100 g)^[4]

-10°C	0°C	10°C	18°C	20°C	25°C	30°C	40°C	50°C	60°C	80°C	100°C	120°C	140°C	160°C
89.4	91.9	94.5	96.1	96.5	97.6	99.2	101.6	104.1	107.5	113.7	120.2	127.5	138.1	163.1

Solubility curve (g/100 g)

Preparations

Chemical reactions

Electrolytic dissociation

Electrolytic dissociation of magnesium bromide yields magnesium ion and bromide ion.

Electrolytic dissociation of magnesium bromide ◆ Δ_rG −158.9 kJ/mol K 6.89 × 10²⁷ pK −27.84: MgBr₂Magnesium bromide
⟶
Mg²⁺Magnesium ion + 2Br⁻Bromide ion

Reaction with nonvolatile acid

The reaction of magnesium bromide and nonvolatile acid yields salt of non volatile acid and hydrogen bromide.

Reaction of magnesium bromide and sulfuric acid ◆ Δ_rG −83.7 kJ/mol K 4.61 × 10¹⁴ pK −14.66: MgBr₂Magnesium bromide + H₂SO₄Sulfuric acid
⟶
MgSO₄Magnesium sulfate + 2HBr↑Hydrogen bromide

Reaction of magnesium bromide and sulfuric acid: MgBr₂Magnesium bromide + 2H₂SO₄Sulfuric acid
⟶
Mg(HSO₄)₂Magnesium hydrogensulfate + 2HBr↑Hydrogen bromide

Reaction of magnesium bromide and perchloric acid ◆ Δ_rG 101.0 kJ/mol K 0.20 × 10⁻¹⁷ pK 17.69: MgBr₂Magnesium bromide + 2HClO₄Perchloric acid
⟶
Mg(ClO₄)₂Magnesium perchlorate + 2HBr↑Hydrogen bromide

Reaction of magnesium bromide and metasilicic acid ◆ Δ_rG 27.2 kJ/mol K 0.17 × 10⁻⁴ pK 4.77: MgBr₂Magnesium bromide + H₂SiO₃Metasilicic acid
🔥
⟶
MgSiO₃Magnesium metasilicate + 2HBr↑Hydrogen bromide

Reaction of magnesium bromide and permanganic acid: MgBr₂Magnesium bromide + 2HMnO₄Permanganic acid
⟶
Mg(MnO₄)₂Magnesium permanganate + 2HBr↑Hydrogen bromide

Reaction with reducing species

The reaction of sodium and magnesium bromide yields sodium bromide and magnesium.

Reaction of sodium and magnesium bromide ◆ Δ_rG −194.2 kJ/mol K 1.05 × 10³⁴ pK −34.02: 2NaSodium + MgBr₂Magnesium bromide
⟶
2NaBrSodium bromide + MgMagnesium

Reaction with oxidizing species

The reaction of magnesium bromide and oxidizing species yields a variety of products.

Reaction of magnesium bromide and oxygen ◆ Δ_rG −124.3 kJ/mol K 5.98 × 10²¹ pK −21.78: 2MgBr₂Magnesium bromide + O₂Oxygen
⟶
2MgOMagnesium oxide + 2Br₂Bromine

Reaction of magnesium bromide and chlorine ◆ Δ_rG −88.0 kJ/mol K 2.61 × 10¹⁵ pK −15.42: MgBr₂Magnesium bromide + Cl₂Chlorine
⟶
MgCl₂Magnesium chloride + Br₂Bromine

Reaction of magnesium bromide and potassium permanganate ◆ Δ_rG −384.8 kJ/mol K 2.59 × 10⁶⁷ pK −67.41: 6MgBr₂Magnesium bromide + 2KMnO₄Potassium permanganate
⟶
6MgOMagnesium oxide + 5Br₂Bromine + 2MnOManganese(II) oxide + 2KBrPotassium bromide

Reaction of magnesium bromide and potassium permanganate ◆ Δ_rG −478.0 kJ/mol K 5.52 × 10⁸³ pK −83.74: 5MgBr₂Magnesium bromide + 2KMnO₄Potassium permanganate
⟶
5MgOMagnesium oxide + 4Br₂Bromine + Mn₂O₃Manganese(III) oxide + 2KBrPotassium bromide

Reaction of magnesium bromide and nitric acid ◆ Δ_rG −134.4 kJ/mol K 3.51 × 10²³ pK −23.55: MgBr₂Magnesium bromide + 4HNO₃Nitric acid
⟶
Mg(NO₃)₂Magnesium nitrate + Br₂Bromine + 2NO₂↑Nitrogen dioxide + 2H₂OWater

Reaction with oxidizing species under acidic condition

The reaction of magnesium bromide, oxidizing species, and hydrogen ion yields a variety of products.

Reaction of magnesium bromide and potassium permanganate under acidic condition ◆ Δ_rG −399.6 kJ/mol K 1.02 × 10⁷⁰ pK −70.01: 5MgBr₂Magnesium bromide + 2KMnO₄Potassium permanganate + 16H⁺Hydrogen ion
⟶
5Mg²⁺Magnesium ion + 5Br₂Bromine + 2Mn²⁺Manganese(II) ion + 2K⁺Potassium ion + 8H₂OWater

Reaction of magnesium bromide and potassium permanganate under acidic condition ◆ Δ_rG −399.6 kJ/mol K 1.02 × 10⁷⁰ pK −70.01: 6MgBr₂Magnesium bromide + 2KMnO₄Potassium permanganate + 16H⁺Hydrogen ion
⟶
6Mg²⁺Magnesium ion + 5Br₂Bromine + 2Mn²⁺Manganese(II) ion + 2KBrPotassium bromide + 8H₂OWater

Reaction with oxidizing species under neutral condition

The reaction of magnesium bromide, oxidizing species, and water yields a variety of products.

Reaction of magnesium bromide and potassium permanganate under neutral condition ◆ Δ_rG −586.7 kJ/mol K 6.10 × 10¹⁰² pK −102.79: 4MgBr₂Magnesium bromide + 2KMnO₄Potassium permanganate + 4H₂OWater
⟶
4Mg(OH)₂Magnesium hydroxide + 3Br₂Bromine + 2MnO₂Manganese(IV) oxide + 2KBrPotassium bromide

Reaction of magnesium bromide and potassium permanganate under neutral condition ◆ Δ_rG −630.1 kJ/mol K 2.45 × 10¹¹⁰ pK −110.39: 5MgBr₂Magnesium bromide + 2KMnO₄Potassium permanganate + 5H₂OWater
⟶
5Mg(OH)₂Magnesium hydroxide + 4Br₂Bromine + Mn₂O₃Manganese(III) oxide + 2KBrPotassium bromide

Reaction of magnesium bromide and oxygen under neutral condition ◆ Δ_rG −185.2 kJ/mol K 2.79 × 10³² pK −32.45: 2MgBr₂Magnesium bromide + O₂Oxygen + 2H₂OWater
⟶
2Mg(OH)₂Magnesium hydroxide + 2Br₂Bromine

Precipitation reaction

When a certain chemical species is present in aqueous solution, it reacts with magnesium bromide to form a precipitate.

Reaction of magnesium bromide and sodium fluoride ◆ Δ_rG −177.4 kJ/mol K 1.20 × 10³¹ pK −31.08: MgBr₂Magnesium bromide + 2NaFSodium fluoride
💧
⟶
MgF₂↓Magnesium fluoride + 2NaBrSodium bromide

Reaction of magnesium bromide and potassium fluoride ◆ Δ_rG −252.2 kJ/mol K 1.53 × 10⁴⁴ pK −44.18: MgBr₂Magnesium bromide + 2KFPotassium fluoride
💧
⟶
MgF₂↓Magnesium fluoride + 2KBrPotassium bromide

Reaction of magnesium bromide and copper(II) fluoride: MgBr₂Magnesium bromide + CuF₂Copper(II) fluoride
💧
⟶
MgF₂↓Magnesium fluoride + CuBr₂Copper(II) bromide

Reaction of magnesium bromide and rubidium fluoride ◆ Δ_rG −57.8 kJ/mol K 1.34 × 10¹⁰ pK −10.13: MgBr₂Magnesium bromide + 2RbFRubidium fluoride
💧
⟶
MgF₂↓Magnesium fluoride + 2RbBrRubidium bromide

Reaction of magnesium bromide and silver(I) fluoride ◆ Δ_rG −57.8 kJ/mol K 1.34 × 10¹⁰ pK −10.13: MgBr₂Magnesium bromide + 2AgFSilver(I) fluoride
💧
⟶
MgF₂↓Magnesium fluoride + 2AgBr↓Silver(I) bromide

Electrolysis of aqueous solution

Electrolysis of aqueous magnesium bromide yields a variety of products.

Electrolysis of aqueous magnesium bromide with water as oxidizing agent ◆ Δ_rG 175.0 kJ/mol K 0.22 × 10⁻³⁰ pK 30.66: MgBr₂Magnesium bromide + H₂OWater
💧⚡
⟶
MgOMagnesium oxide + Br₂Bromine + H₂↑Hydrogen

Electrolysis of aqueous magnesium bromide with water as oxidizing agent ◆ Δ_rG 144.5 kJ/mol K 0.48 × 10⁻²⁵ pK 25.32: MgBr₂Magnesium bromide + 2H₂OWater
💧⚡
⟶
Mg(OH)₂Magnesium hydroxide + Br₂Bromine + H₂↑Hydrogen

Electrolysis of aqueous magnesium bromide without water as reactant ◆ Δ_rG 503.8 kJ/mol K 0.55 × 10⁻⁸⁸ pK 88.26: MgBr₂Magnesium bromide
💧⚡
⟶
MgMagnesium + Br₂Bromine

Electrolysis of water ◆ Δ_rG 474.258 kJ/mol K 0.82 × 10⁻⁸³ pK 83.09: 2H₂OWater
⚡
⟶
2H₂↑Hydrogen + O₂↑Oxygen

Electrolysis of aqueous magnesium bromide with water as non-redox agent ◆ Δ_rG 2450.8 kJ/mol K 0.43 × 10⁻⁴²⁹ pK 429.36: 3MgBr₂Magnesium bromide + 3H₂OWater
💧⚡
⟶
3MgMagnesium + HBrO₃Bromic acid + 5HBr↑Hydrogen bromide

Molten salt electrolysis

Molten salt electrolysis of magnesium bromide yields magnesium and bromine.

Molten salt electrolysis of magnesium bromide ◆ Δ_rG 503.8 kJ/mol K 0.55 × 10⁻⁸⁸ pK 88.26: MgBr₂Magnesium bromide
🔥⚡
⟶
MgMagnesium + Br₂Bromine

References

List of references

1
James G. Speight (2017)
Lange's Handbook of Chemistry, 17th edition
https://www.accessengineeringlibrary.com/content/book/9781259586095
McGraw Hill Education
- Amazon
Citation list
- ^ Density, 3.722 g/cm³ - p.51
- ^ Melting point, 711 °C - p.51
- ^ Boiling point, 1158 °C - p.51
- ^ Enthalpy of fusion, 39.3 kJ · mol⁻¹ - p.304
- ^ Enthalpy of vaporization, 149 kJ · mol⁻¹ - p.304
- ^ Enthalpy of vaporization at 25°C, 222 kJ · mol⁻¹ - p.304
- ^ Solubility in Water (g/100 g), See the table - p.338
2
John R. Rumble Jr, David R. Lide, Thomas J. Bruno (2019)
CRC Handbook of Chemistry and Physics 100th Edition
https://www.routledge.com/CRC-Handbook-of-Chemistry-and-Physics/book-series/CRCHANCHEPHY
CRC Press
- Amazon
Citation list
- ^ Enthalpy of fusion, 39.3 kJ · mol⁻¹ - p.6-158
3
Janiel J. Reed (1989)
The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI Units
https://doi.org/10.18434/M32124
National Institute of Standards and Technology (NIST)
Citation list
4
Atherton Seidell (1919)
Solubilities of Inorganic and Organic Compounds: A Compilation of Quantitative Solubility Data From the Periodical Literature
D. Van Nostrand Company
- Amazon
Citation list
- ^ Solubility in Water (g/100 g), See the table - p.379

Δ_rG	−503.8 kJ/mol
K	1.83 × 10⁸⁸
pK	−88.26

Δ_rG	−37.6 kJ/mol
K	3.87 × 10⁶
pK	−6.59

Δ_rG	−68.1 kJ/mol
K	8.52 × 10¹¹
pK	−11.93

Δ_rG	126.9 kJ/mol
K	0.59 × 10⁻²²
pK	22.23

Magnesium bromide

Names

List of substance names

Formulae and structures

List of formulae

Properties

List of substance properties

Constituents

Constituent ions

Constituent atoms

Ratio of atoms

Thermodynamic properties

Phase transition properties

Standard thermodynamic properties

Solubility

Qualitative solubility

Solubility in water (g/100 g)[1]

Solubility in water (g/100 g)[4]

Solubility curve (g/100 g)

Preparations

Reaction of metal and nonmetal

Reaction of acid and base

Reaction of basic oxide and acid

Reaction of salt of weak acid and strong acid

Reaction of salt of weak base and strong base

Reaction of active metal and acid

Chemical reactions

Electrolytic dissociation

Reaction with nonvolatile acid

Reaction with reducing species

Reaction with oxidizing species

Reaction with oxidizing species under acidic condition

Reaction with oxidizing species under neutral condition

Precipitation reaction

Electrolysis of aqueous solution

Molten salt electrolysis

References

List of references

Related substances

Bromide of alkaline earth metal

Halide of magnesium

Acid

Base and basic oxide

Related categories

Classification by constituent

Type of substance

State of substance

Property of substance

Solubility of substance

Color of substance

Odor of substance

Solubility in water (g/100 g)^[1]

Solubility in water (g/100 g)^[4]