| Identification | More | [Name]
Chromium oxide | [CAS]
1308-38-9 | [Synonyms]
383 GREEN NATO
CHROME GREEN
CHROME OXIDE
CHROME OXIDE GREEN GN
CHROME OXIDE GREEN GN-M
CHROME OXIDE GREEN GN-Z
CHROME OXIDE GREEN GX
CHROMIA
CHROMIC OXIDE
CHROMIC OXIDE GREEN
CHROMIC SESQUIOXIDE
CHROMIUM(+3)OXIDE
CHROMIUM GREEN
CHROMIUM (IC) OXIDE
CHROMIUM (IC) SESQUIOXIDE
CHROMIUM (III) OXIDE
CHROMIUM(III) OXIDE, GREEN
CHROMIUM OXIDE
CHROMIUM OXIDE, GREEN
CHROMIUM SESQUIOXIDE | [EINECS(EC#)]
215-160-9 | [Molecular Formula]
Cr2O3 | [MDL Number]
MFCD00010949 | [Molecular Weight]
151.99 | [MOL File]
1308-38-9.mol |
| Chemical Properties | Back Directory | [Appearance]
Chromium oxide is a bright green, odorless powder | [Melting point ]
2435 °C
| [Boiling point ]
4000 °C
| [density ]
5.21
| [refractive index ]
2.551 | [Fp ]
3000°C | [storage temp. ]
Room Temperature | [solubility ]
Insoluble in all solvents | [form ]
powder
| [color ]
Pale to dark green | [Specific Gravity]
5.22 | [Odor]
at 100.00?%. odorless | [Stability:]
Stable. | [Water Solubility ]
Insoluble | [Crystal Structure]
Trigonal | [Merck ]
14,2234 | [Exposure limits]
NIOSH: IDLH 25 mg/m3; TWA 0.5 mg/m3 | [CAS DataBase Reference]
1308-38-9(CAS DataBase Reference) | [NIST Chemistry Reference]
Chromium(iii) oxide(1308-38-9) | [EPA Substance Registry System]
1308-38-9(EPA Substance) |
| Safety Data | Back Directory | [Safety Statements ]
S24/25:Avoid contact with skin and eyes . | [WGK Germany ]
-
| [RTECS ]
GB6475000
| [TSCA ]
Yes | [HS Code ]
28199090 | [Safety Profile]
Confirmed carcinogen
with experimental tumorigenic data.
Mutation data reported. Probably a severe | [Hazardous Substances Data]
1308-38-9(Hazardous Substances Data) |
| Questions and Answers (Q&A) | Back Directory | [Uses]
Chromium(III) oxide is used as pigment for coloring green on glass and fabrics. Other important applications are in metallurgy; as a component of refractory bricks, abrasives and ceramics; and as a catalyst in hydrogenation, hydrogenolysis and many other organic conversion reactions. It also is used to prepare other chromium salts.
| [Chemical Properties]
Green hexagonal crystal system; corundum type structure; density 5.22 g/cm3; melts at 2,330°C; vaporizes above 3,000°C; insoluble in water and alcohol.
| [Description]
Chromium oxide green, also known as chromium sesquioxide or chromia, is one of four oxides of chromium, chemical formula Cr2O3. It is commonly called ‘chrome green’ when used as a pigment; however it was referred to as ‘viridian’ when it was first discovered.
Chrome oxide is a very refractory ceramic colorant (even a 50% mix with a high borax frit will not even begin to melt it in a crucible). Chrome oxide is the only stable oxide of the metal chromium. It is a bright to dark green crystalline powder insoluble in alkalis and acids. It is manufactured from the mineral Chromite mined in southern Africa, Asia, Turkey and Cuba. As with other powerful coloring agents, chrome must be milled fine enough to eliminate specking in glass or glaze.
Chromium is a 'fast' colorant, meaning can produce strong green colors under all furnace conditions, slow or fast, reducing or oxidizing. It is also a flat colorant (due to its refractory nature), it usually produces an army helmet opaque green. It is powerful, typically only 2% will produce a dark color. It cannot be used to make a metallic glaze.
Chrome oxide is usually employed in raw glazes whereas potassium dichromate is used in fritted glazes.
| [Preparation]
Chromium(III) oxide may be prepared by several methods which include (i) burning the metal in oxygen, (ii) by heating chromium(III) hydroxide, (iii) by heating chromium(VI) oxide, CrO3,(iv) thermal decomposition of dry ammonium dichromate, (NH4)2Cr2O7, and (v) by heating a mixture of sodium chromate, Na2CrO4 or sodium dichromate, Na2Cr2O7 with sulfur followed by treatment with water to remove the soluble sodium sulfate formed in the reaction.
| [Reactions]
Chromium(III) oxide is amphoteric. Although insoluble in water, it dissolves in acid to produce hydrated chromium ion, [Cr(H2O)6]3+. It dissolves in concentrated alkali to yield chromite ion. When heated with finely divided aluminum or carbon it is reduced to chromium metal:
Cr2O3 + 3Al 2Cr + Al2O3
Heating with chlorine and carbon yields chromium(III) chloride:
Cr2O3 + 3Cl2 + 3C 2CrCl3 + 3CO
|
| Hazard Information | Back Directory | [Hazard]
Toxic by ingestion and inhalation. | [Potential Exposure]
Chromium(III) oxide is used as a paint pigment, a fixative for certain textile dyes; in the manufacture of chromium; and a catalyst. | [First aid]
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a Medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit | [Shipping]
UN3086 Toxic solids, oxidizing, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, 5.1-Oxidizer. Technical Name Required. Spill Handling: Evacuate persons not wearing protective equipment from the danger area of spill or leak until cleanup is complete. Remove all ignition sources. Collect powdered material in the most convenient and safe manner and deposit in sealed containers. Ventilate area after clean-up is complete. It may be necessary to contain and dispose of this chemical as a hazardous waste. If material or contaminated runoff enters waterways, notify downstream users of potentially contaminated waters. Contact your local or federal environmental protection agency for specific recommendations. If employees are required to clean-up spills, they must be properly trained and equipped. OSHA 1910.120(q) may be applicable. | [Incompatibilities]
A strong oxidizer. Contact with reducing agents; organics, and combustibles may be violent | [Physical properties]
Green hexagonal crystal system; corundum type structure; density 5.22 g/cm3; melts at 2,330°C; vaporizes above 3,000°C; insoluble in water and alcohol. | [Definition]
chromium sesquioxide: A green crystallinewater-insoluble salt, Cr2O3; r.d. 5.21;m.p. 2435°C; b.p. 4000°C. It is obtainedby heating chromium in astream of oxygen or by heating ammoniumdichromate. The industrialpreparation is by reduction ofsodium dichromate with carbon.Chromium(III) oxide is amphoteric,dissolving in acids to give chromium(III) ions and in concentratedsolutions of alkalis to give chromites.It is used as a green pigment in glass,porcelain, and oil paint. | [General Description]
Chromium (III) oxide is a chromium complex in which the chromium ion is in +3 oxidation state. The synthesis of its sub-micron powder has been reported.? The IR and Raman spectra of chromium (III) oxide have been studied.? The impact of adding lysozyme on the stability of chromium (III) oxide (Cr2O3) suspension has been evaluated.? | [Flammability and Explosibility]
Notclassified | [storage]
(1) Color Code—Blue: Health Hazard/Poison:Store in a secure poison location. (2) Color Code—Yellow:Reactive Hazard; Store in a location separate from othermaterials, especially flammables and combustibles.Chromium(III) oxide must be stored to avoid contact withstrong oxidizers (such as chlorine, bromine, and fluorine),glycerol, and oxygen difluoride, since violent reactionsoccur. A regulated, marked area should be establishedwhere chromium(III) oxide is handled, used, or stored.Store in tightly closed containers in a cool, well-ventilatedarea. | [Properties and Applications]
|
TEST ITEMS
|
SPECIFICATION
|
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APPEARANCE
|
GREEN POWDER
|
|
CONTENT OF
Cr
2
O
3
|
85% min
|
|
SHADE
|
YELLOWISH
|
|
HYDROTROPE
|
0.5% max
|
|
OIL ABSORPTION
|
25% max
|
|
RESIDUE ON 45 MESH
|
0.1% max
|
|
WATER SOLUBLE
|
0.3% max
|
|
VOLATITE 105 °C
|
0.05% max
|
|
TINTING STRENGTH
|
95-100 %
|
|
pH VALUE OF AQUEOUS SUSPENSION
|
5-8
|
| [Structure and conformation]
Chromium oxide is a dense, crystalline material, density 5.2 g/cm3, of the corundum type. It is quite hard-abut 9 on the Moh scale-which makes it a good grinding material, but too abrasive for many pigment applications. The particle size depends on the manufacturing process, but it is distributed around mean values in the range 0.5-0.6 μm. The refractive index of chromium oxide is quite high, 2.5, which is almost as high as that of rutile TiO2, 2.7. Chromium oxide pigments are green with an olive green tint. Small particles are lighter green with a yellowish hue, whereas larger particles are darker, with a bluish tint. Chromium oxide pigments are very inert materials with outstanding lightfastness and excellent resistance to acids, alkalis, and high temperatures. |
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