Home
Chemical substances
Manganese(III) oxide

Manganese(III) oxide

Last updated: March 19, 2023

Manganese(III) oxide is an inorganic compound with formula Mn₂O₃.

Table of contents

Names

List of substance names

Nomenclature

Name

Typical name: Manganese(III) oxide

Compositional nomenclature: Manganese(III) oxide; Dimanganese trioxide

Other names: Manganic oxide

Formulae and structures

List of formulae

Formula name

Formula

Typical formula: Mn₂O₃

Compositional formula: Mn₂O₃

Structural formula

Lewis structure

Colored Lewis structure

Properties

List of substance properties

Item

Value

Name: Manganese(III) oxide

Formula: Mn₂O₃

Appearance: Black brown solid

Odor: Odorless

Molar mass: 157.873 g/mol

Density: 4.89 g/cm³^[1]
Solid

Melting point: 877 °C^[1]
Decompose → Mn₃O₄, O₂

Boiling point: –

Constituents

Constituent ions

Ion	Name	Charge number	Number
Mn³⁺	Manganese(III) ion	3	2
O²⁻	Oxide ion	-2	3

Constituent atoms

Atom	Name	Oxidation state	Number
Mn	Mangenese	+3	2
O	Oxygen	−2	3

Ratio of atoms

Atom	Atomic weight	Number	Atomic ratio	Weight ratio
Mn	54.938	2	40.00%	69.60%
O	15.999	3	60.00%	30.40%

Thermodynamic properties

Phase transition properties

Item

Value

Enthalpy of fusion: –

Enthalpy of vaporization: –

Enthalpy of vaporization at 25°C: –

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	−959.0^[2]	−881.1^[2]	110.5^[2]	107.65^[2]

Solubility

Qualitative solubility

Reactive: HCl (aq)^[1]Hydrochloric acid

Miscible

Very soluble

Soluble: HCl (aq)^[1]Hydrochloric acid

Slightly soluble

Very slightly soluble

Insoluble: H₂O^[1]Water

Hazards

GHS label^[3]

Item

Value

Hazard pictograms: GHS08: Health hazard

Signal word: Danger

Hazard statements: H360: May damage fertility or the unborn child; H370: Causes damage to organs; H370: Causes damage to respiratory system; H372: Causes damage to organs through prolonged or repeated exposure; H372: Causes damage to nervous system through prolonged or repeated exposure; H372: Causes damage to respiratory system through prolonged or repeated exposure

Physical hazards^[3]

Classification	Category	Label	Hazard statement
Explosives	Not applicable
Flammable gases	Not applicable
Aerosols	Not applicable
Oxidizing gases	Not applicable
Gases under pressure	Not applicable
Flammable liquids	Not applicable
Flammable solids	Classification not possible
Self reactive substances and mixtures	Not applicable
Pyrophoric liquids	Not applicable
Pyrophoric solids	Classification not possible
Self heating substances and mixtures	Classification not possible
Substances and mixtures which in contact with water emit flammable gases	Not classified
Oxidizing liquids	Not applicable
Oxidizing solids	Classification not possible
Organic peroxides	Not applicable
Substances and mixtures corrosive to metals	Classification not possible
Desensitized explosives	No data

Health hazards^[3]

Classification	Category	Label	Hazard statement
Acute oral toxicity	Classification not possible
Acute dermal toxicity	Classification not possible
Acute inhalation toxicity by gas	Not applicable
Acute inhalation toxicity by vapor	Not applicable
Acute inhalation toxicity by dust or mist	Classification not possible
Skin corrosion irritation	Classification not possible
Serious eye damage eye irritation	Classification not possible
Respiratory sensitization	Classification not possible
Skin sensitization	Classification not possible
Germ cell mutagenicity	Classification not possible
Carcinogenicity	Classification not possible
Reproductive toxicity	Category 1B	Danger	H360: May damage fertility or the unborn child
Specific target organ toxicity single exposure	Category 1 (Respiratory system)	Danger	H370: Causes damage to organs H370: Causes damage to respiratory system
Specific target organ toxicity repeated exposure	Category 1 (Nervous system, Respiratory system)	Danger	H372: Causes damage to organs through prolonged or repeated exposure H372: Causes damage to nervous system through prolonged or repeated exposure H372: Causes damage to respiratory system through prolonged or repeated exposure
Aspiration hazard	Classification not possible

Environmental hazards^[3]

Classification	Category	Label	Hazard statement
Hazardous to the aquatic environment short term	No data
Hazardous to the aquatic environment long term	No data
Hazardous to the ozone layer	No data

Preparations

Reaction of metal and nonmetal

The reaction of metal and nonmetal can yield manganese(III) oxide.

Reaction of manganese and oxygen ◆ Δ_rG −1762.2 kJ/mol K 5.30 × 10³⁰⁸ pK −308.72: 4MnManganese + 3O₂Oxygen
⟶
2Mn₂O₃Manganese(III) oxide

Reaction of manganese and ozone ◆ Δ_rG −1044.3 kJ/mol K 8.98 × 10¹⁸² pK −182.95: 2MnManganese + O₃Ozone
⟶
Mn₂O₃Manganese(III) oxide

Chemical reactions

Reaction with reducing nonmetal

The reaction of reducing nonmetal and manganese(III) oxide yields elementary substance/oxide and nonmetal oxide.

Reaction of hydrogen and manganese(III) oxide ◆ Δ_rG 169.7 kJ/mol K 0.19 × 10⁻²⁹ pK 29.73: 3H₂Hydrogen + Mn₂O₃Manganese(III) oxide
🔥
⟶
2MnManganese + 3H₂OWater

Reaction of carbon and manganese(III) oxide ◆ Δ_rG 469.6 kJ/mol K 0.54 × 10⁻⁸² pK 82.27: 3CCarbon + Mn₂O₃Manganese(III) oxide
🔥
⟶
2MnManganese + 3CO↑Carbon monoxide

Reaction of hydrogen and manganese(III) oxide ◆ Δ_rG −81.8 kJ/mol K 2.14 × 10¹⁴ pK −14.33: H₂Hydrogen + Mn₂O₃Manganese(III) oxide
🔥
⟶
2MnOManganese(II) oxide + H₂OWater

Reaction of carbon and manganese(III) oxide ◆ Δ_rG 18.1 kJ/mol K 0.67 × 10⁻³ pK 3.17: CCarbon + Mn₂O₃Manganese(III) oxide
🔥
⟶
2MnOManganese(II) oxide + CO↑Carbon monoxide

Reaction with reducing species

The reaction of reducing species and manganese(III) oxide yields a variety of products.

Reaction of sodium and manganese(III) oxide ◆ Δ_rG −245.3 kJ/mol K 9.43 × 10⁴² pK −42.97: 6NaSodium + Mn₂O₃Manganese(III) oxide
⟶
3Na₂OSodium oxide + 2MnManganese

Reaction of sodium and manganese(III) oxide ◆ Δ_rG −220.2 kJ/mol K 3.78 × 10³⁸ pK −38.58: 2NaSodium + Mn₂O₃Manganese(III) oxide
⟶
Na₂OSodium oxide + 2MnOManganese(II) oxide

Reaction of hydrogen sulfide and manganese(III) oxide ◆ Δ_rG −166.4 kJ/mol K 1.42 × 10²⁹ pK −29.15: 3H₂SHydrogen sulfide + Mn₂O₃Manganese(III) oxide
⟶
SSulfur + 2MnSManganese(II) sulfide + 3H₂OWater

Reaction with oxidizing species

The reaction of manganese(III) oxide and oxidizing species yields a variety of products.

Reaction of manganese(III) oxide and oxygen ◆ Δ_rG −98.4 kJ/mol K 1.73 × 10¹⁷ pK −17.24: 2Mn₂O₃Manganese(III) oxide + O₂Oxygen
⟶
4MnO₂Manganese(IV) oxide

Reaction of manganese(III) oxide and nitric acid ◆ Δ_rG −50.1 kJ/mol K 5.99 × 10⁸ pK −8.78: 3Mn₂O₃Manganese(III) oxide + 2HNO₃Nitric acid
⟶
6MnO₂Manganese(IV) oxide + 2NO↑Nitrogen monoxide + H₂OWater

Reaction of manganese(III) oxide and nitric acid ◆ Δ_rG −133.7 kJ/mol K 2.65 × 10²³ pK −23.42: 6Mn₂O₃Manganese(III) oxide + 2HNO₃Nitric acid
⟶
12MnO₂Manganese(IV) oxide + N₂↑Nitrogen + H₂↑Hydrogen

Reaction of manganese(III) oxide and potassium permanganate ◆ Δ_rG 75.3 kJ/mol K 0.64 × 10⁻¹³ pK 13.19: 3Mn₂O₃Manganese(III) oxide + 2KMnO₄Potassium permanganate
🔥
⟶
8MnO₂Manganese(IV) oxide + K₂OPotassium oxide

Reaction with oxidizable species

The reaction of oxidizable species and manganese(III) oxide yields a variety of products.

Reaction of copper and manganese(III) oxide ◆ Δ_rG −52.8 kJ/mol K 1.78 × 10⁹ pK −9.25: CuCopper + 3Mn₂O₃Manganese(III) oxide
⟶
CuOCopper(II) oxide + 2Mn₃O₄Manganese(II,III) oxide

Reaction of copper and manganese(III) oxide ◆ Δ_rG −69.1 kJ/mol K 1.28 × 10¹² pK −12.11: 2CuCopper + 3Mn₂O₃Manganese(III) oxide
⟶
Cu₂OCopper(I) oxide + 2Mn₃O₄Manganese(II,III) oxide

Reaction of iron(II) oxide and manganese(III) oxide: 9FeOIron(II) oxide + Mn₂O₃Manganese(III) oxide
⟶
3Fe₃O₄Iron(II,III) oxide + 2MnManganese

Reaction of iron(II) oxide and manganese(III) oxide: 6FeOIron(II) oxide + Mn₂O₃Manganese(III) oxide
⟶
3Fe₂O₃Iron(III) oxide + 2MnManganese

Reaction with oxidizing species under neutral condition

The reaction of manganese(III) oxide, potassium permanganate, and water yields manganese(IV) oxide and potassium hydroxide.

Reaction of manganese(III) oxide and potassium permanganate under neutral condition ◆ Δ_rG −123.7 kJ/mol K 4.69 × 10²¹ pK −21.67: 3Mn₂O₃Manganese(III) oxide + 2KMnO₄Potassium permanganate + H₂OWater
⟶
8MnO₂Manganese(IV) oxide + 2KOHPotassium hydroxide

Reaction with oxidizable species under neutral condition

The reaction of oxidizable species, manganese(III) oxide, and water yields a variety of products.

Reaction of copper and manganese(III) oxide under neutral condition ◆ Δ_rG −20.6 kJ/mol K 4.06 × 10³ pK −3.61: 2CuCopper + Mn₂O₃Manganese(III) oxide + 2H₂OWater
🔥
⟶
Cu₂OCopper(I) oxide + 2Mn(OH)₂Manganese(II) hydroxide

Reaction of copper and manganese(III) oxide under neutral condition ◆ Δ_rG −4.3 kJ/mol K 5.67 × 10⁰ pK −0.75: CuCopper + Mn₂O₃Manganese(III) oxide + 2H₂OWater
🔥
⟶
CuOCopper(II) oxide + 2Mn(OH)₂Manganese(II) hydroxide

Reaction of potassium iodide and manganese(III) oxide under neutral condition ◆ Δ_rG 205.7 kJ/mol K 0.92 × 10⁻³⁶ pK 36.04: 2KIPotassium iodide + 3Mn₂O₃Manganese(III) oxide + H₂OWater
🔥
⟶
2KOHPotassium hydroxide + I₂Iodine + 2Mn₃O₄Manganese(II,III) oxide

Reaction of potassium iodide and manganese(III) oxide under neutral condition ◆ Δ_rG 254.1 kJ/mol K 0.30 × 10⁻⁴⁴ pK 44.52: 2KIPotassium iodide + Mn₂O₃Manganese(III) oxide + 3H₂OWater
🔥
⟶
2KOHPotassium hydroxide + I₂Iodine + 2Mn(OH)₂Manganese(II) hydroxide

Reaction with hardly oxidizable species

The reaction of hardly oxidizable species and manganese(III) oxide yields a variety of products.

Reaction of hydrogen chloride and manganese(III) oxide ◆ Δ_rG −139.5 kJ/mol K 2.75 × 10²⁴ pK −24.44: 6HClHydrogen chloride + Mn₂O₃Manganese(III) oxide
⟶
Cl₂Chlorine + 2MnCl₂Manganese(II) chloride + 3H₂OWater

Reaction of gold and manganese(III) oxide: 2AuGold + 3Mn₂O₃Manganese(III) oxide
🔥
⟶
Au₂O₃Gold(III) oxide + 6MnOManganese(II) oxide

Reaction of gold and manganese(III) oxide: 2AuGold + 9Mn₂O₃Manganese(III) oxide
🔥
⟶
Au₂O₃Gold(III) oxide + 6Mn₃O₄Manganese(II,III) oxide

Reaction of sodium chloride and manganese(III) oxide ◆ Δ_rG 750.5 kJ/mol K 0.33 × 10⁻¹³¹ pK 131.48: NaClSodium chloride + 4Mn₂O₃Manganese(III) oxide
🔥
⟶
NaClO₄Sodium perchlorate + 8MnOManganese(II) oxide

Reaction of sodium chloride and manganese(III) oxide ◆ Δ_rG 587.8 kJ/mol K 0.11 × 10⁻¹⁰² pK 102.98: NaClSodium chloride + 3Mn₂O₃Manganese(III) oxide
🔥
⟶
NaClO₃Sodium chlorate + 6MnOManganese(II) oxide

Reaction with hardly oxidizable species under neutral condition

The reaction of hardly oxidizable species, manganese(III) oxide, and water yields a variety of products.

Reaction of gold and manganese(III) oxide under neutral condition ◆ Δ_rG 308.2 kJ/mol K 0.10 × 10⁻⁵³ pK 53.99: 2AuGold + 9Mn₂O₃Manganese(III) oxide + 3H₂OWater
🔥
⟶
2Au(OH)₃Gold(III) hydroxide + 6Mn₃O₄Manganese(II,III) oxide

Reaction of gold and manganese(III) oxide under neutral condition ◆ Δ_rG 453.6 kJ/mol K 0.34 × 10⁻⁷⁹ pK 79.47: 2AuGold + 3Mn₂O₃Manganese(III) oxide + 9H₂OWater
🔥
⟶
2Au(OH)₃Gold(III) hydroxide + 6Mn(OH)₂Manganese(II) hydroxide

Reaction of sodium chloride and manganese(III) oxide under neutral condition ◆ Δ_rG 323.3 kJ/mol K 0.23 × 10⁻⁵⁶ pK 56.64: 2NaClSodium chloride + 3Mn₂O₃Manganese(III) oxide + H₂OWater
🔥
⟶
2NaOHSodium hydroxide + Cl₂↑Chlorine + 2Mn₃O₄Manganese(II,III) oxide

Reaction of sodium chloride and manganese(III) oxide under neutral condition ◆ Δ_rG 630.7 kJ/mol K 0.32 × 10⁻¹¹⁰ pK 110.49: NaClSodium chloride + 4Mn₂O₃Manganese(III) oxide + 8H₂OWater
🔥
⟶
NaClO₄Sodium perchlorate + 8Mn(OH)₂Manganese(II) hydroxide

Decomposition

Decomposition of manganese(III) oxide yields a variety of products.

Decomposition of manganese(III) oxide ◆ Δ_rG 53.1 kJ/mol K 0.50 × 10⁻⁹ pK 9.30: Mn₂O₃Manganese(III) oxide
🔥
⟶
MnO₂Manganese(IV) oxide + MnOManganese(II) oxide

Decomposition of manganese(III) oxide ◆ Δ_rG 13.9 kJ/mol K 0.37 × 10⁻² pK 2.44: 2Mn₂O₃Manganese(III) oxide
🔥
⟶
MnO₂Manganese(IV) oxide + Mn₃O₄Manganese(II,III) oxide

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, 4.89 g/cm³ - p.52
- ^ Melting point, 877 °C - p.52
- ^ Qualitative solubility, Insoluble in water - p.52
- ^ Qualitative solubility, Soluble in hydrochloric acid - p.52
- ^ Qualitative solubility, Reactive with hydrochloric acid - p.52
2
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
3
Chemical Management Center
GHS Classification Results
https://www.nite.go.jp/chem/english/ghs/all_fy_e.html
National Institute of Technology and Evaluation
Citation list

Δ_rG	−1762.2 kJ/mol
K	5.30 × 10³⁰⁸
pK	−308.72

Δ_rG	−1044.3 kJ/mol
K	8.98 × 10¹⁸²
pK	−182.95

Δ_rG	−187.9 kJ/mol
K	8.29 × 10³²
pK	−32.92

Δ_rG	−88.0 kJ/mol
K	2.61 × 10¹⁵
pK	−15.42

Manganese(III) oxide

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

Hazards

GHS label[3]

Physical hazards[3]

Health hazards[3]

Environmental hazards[3]

Preparations

Reaction of metal and nonmetal

Reaction of reducing nonmetal and oxide

Reaction of active metal and water

Decomposition

Comproportionation

Chemical reactions

Reaction with reducing nonmetal

Reaction with reducing species

Reaction with oxidizing species

Reaction with oxidizable species

Reaction with oxidizing species under neutral condition

Reaction with oxidizable species under neutral condition

Reaction with hardly oxidizable species

Reaction with hardly oxidizable species under neutral condition

Decomposition

References

List of references

Related substances

Oxide of group 7 element

Related categories

Classification by constituent

Type of substance

State of substance

Property of substance

Solubility of substance

Color of substance

Odor of substance

GHS label^[3]

Physical hazards^[3]

Health hazards^[3]

Environmental hazards^[3]