Chromium (iii) oxide, frequently called chromia and also referred to as oxo(oxochromiooxy)chromium in IUPAC nomenclature, is an not natural compound include chromium and also oxygen stood for by the chemistry formula Cr2O3 <1>. It naturally occurs as the mineral eskolaite and also is a very insoluble compound with high thermal stability, having actually the properties of both one acid and also a basic <2, 3, 4>.

Chromium (III) Oxide Identification

CAS Number1308-38-9 <1>
PubChem CID517277 <1>
ChemSpider ID451305 <5>
UN Number3077 <1>
EC Number215-160-9 <1>
RTECS NumberGB6475000 <1>

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Chromium (III) Oxide Formula

How is Chromium (III) Oxide Prepared

It is created through the reduction of sodium dichromate making use of sulfur in ~ high temperatures shown by the redox reaction <6>:

Na2Cr2O7 + S → Na2SO4 + Cr2O3

Ammonium dichromate, top top heating, decomposes right into chromium (iii) oxide, water, and nitrogen <7>:

(NH4)2Cr2O7 → Cr2O3 + N2 + 4H2O

Chromium (iii) carbonate is heated to type chromium (iii) oxide and carbon dioxide:

Cr2(CO3)3 → Cr2O3 + 3CO2

Reaction with other Compounds

Chromium (III) Oxide v Hydrochloric Acid

It reacts through dilute hydrochloric mountain to form chromium (iii) chloride and water <8>:

Cr2O3 + 6HCl → 2CrCl3 + 3H2O

Chromium (III) Oxide through Hydrogen Sulfide

When chromium (iii) oxide reacts v gaseous hydrogen sulfide, it returns chromium (iii) sulfide and also water:

Cr2O3 + 3H2S → Cr2S3 + 3H2O

Properties and also Characteristics that Chromium (III) Oxide

General Properties

Molar Mass/Molecular Weight151.989 g/mol <1, 3>

Physical Properties

Color and also AppearanceDry, irradiate or dark green, well crystalline flour <1, 3>
Melting Point2,435 °C, 4,415 °F <1>
Boiling Point4,000 °C, 7,230 °F <1>
Density5.22 g cm-3 <1, 3>
State of issue at room temperatureSolid <1, 3>
SolubilityInsoluble in acetone and alcohol, really slightly dissolve in alkalies and acids <1>
Solubility in WaterPractically insoluble, 2.96 µg/L (20 °C, pH 8), 3.13 µg/L (20 °C, pH 6) <1>
Magnetic Susceptibility (χ) 1960.0 X 10-6 cm3/mol

Atomic Properties

Crystal StructureHexagonal

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Chromium (III) Oxide


Because that its stability, chromium (iii) oxide is provided as the environment-friendly pigment in inks, glasses, and paints and also as a colorant because that ceramics, as well as producing a faint eco-friendly tinge in glazes <8>.It serves together an abrasive for polishing or stropping the edges of razors, knives, and surfaces that optical devices <9>.

Is that Safe

Exposure to chromium (iii) oxide with mouth and also skin can reason acute toxicity <1>. It may reason an allergic skin reaction and serious eye damages <1>. It can likewise cause reproductive toxicity and also is harmful to the unborn child <1>.