Rhodium oxide Chemical Properties

Melting point:

1100°C (dec.)

Density 

8.2 g/mL at 25 °C(lit.)

storage temp. 

under inert gas (nitrogen or Argon) at 2-8°C

form 

Powder

color 

Yellow

Specific Gravity

8.2

Water Solubility 

Insoluble in water, acetone, conc. Hydrochloric acid, Nitric acid, Aqua regia.

Sensitive 

Hygroscopic

Crystal Structure

Corundum type

crystal system

Three sides

Space group

R3c

Lattice constant

a/nm	b/nm	c/nm	α/o	β/o	γ/o	V/nm3
0.5127	0.5127	1.3853	90	90	120	0.3154

Exposure limits

ACGIH: TWA 1 mg/m3
NIOSH: IDLH 100 mg/m3; TWA 0.1 mg/m3

InChIKey

XBBXDTCPEWHXKL-UHFFFAOYSA-N

CAS DataBase Reference

12036-35-0(CAS DataBase Reference)

EPA Substance Registry System

Rhodium oxide (Rh2O3) (12036-35-0)

Safety Information

Hazard Codes 

O;Xi,Xi,O

Risk Statements 

36/38-8

Safety Statements 

22-24/25-37/39-26-17

RIDADR 

3288

WGK Germany 

3

TSCA 

Yes

HazardClass 

6.1(b)

PackingGroup 

III

HS Code 

28259085

MSDS

• Language:English Provider:Dirhodium trioxide
• Language:English Provider:SigmaAldrich
• Language:English Provider:ALFA

Rhodium oxide Usage And Synthesis

Uses

Rh2O3 is used to make rhodium metal and its various salts. Also, the oxide is a catalyst for hydrogenation.

Preparation

Rhodium sesquioxide is obtained by heating rhodium metal to red heat in air.
4Rh + 3O2 → 2Rh2O3
Alternatively, Rh2O3 may be prepared by igniting rhodium nitrate, Rh(NO3)3.
Treating the sesquioxide with alkali first forms a yellow precipitate of pentahydrate, Rh2O3•5H2O, soluble in acid and excess alkali. In excess alkali a black precipitate of trihydrate, Rh2O3•3H2O is obtained. The trihydrate is insoluble in acids.

Chemical Properties

Rhodium oxide is YELLOW POWDER

Physical properties

Gray crystalline solid or amorphous powder; corundum-type structure; density 8.20 g/cm³; decomposes at about 1,100 to 1,150°C; insoluble in water, acids, or aqua regia.
The pentahydrate Rh₂O₃?5H₂O is a yellow precipitate; soluble in acids; partially dissolves in hot water; ignites to form anhydrous oxide.
The trihydrate Rh₂O₃?3H₂O is a black precipitate; insoluble in acids.

Uses

RH₂o₃ is used to make rhodium metal and its various salts. Also, the oxide is a catalyst for hydrogenation.

Uses

Use in the catalytic converters of automobiles. It is also used as an industrial catalyst in the manufacturing of chemical intermediates such as oxo-alcohols, as well as nitric acid and ethanoic (acetic) acid production. It is also an area of interest for new capacitor electrode material researchers, dynamic random access memory (DRAMs) and non volatile random access memories (FeRAMs) makers.

Production Methods

Rhodium(III) oxide, Rh2O3, can be prepared by heating the finely divided metal or its nitrate in air or O2. The rhodium(IV) oxide is also known. Rhodium trihydroxide may be precipitated as a yellow compound by adding the stoichiometric amount of KOH to a solution of RhCl3. The hydroxide is soluble in acids and excess base. When the freshly precipitated Rh(OH)3 is dissolved in HCl at a controlled pH, a yellow solution is first obtained in which the aquochloro complex of Rh behaves as a cation.

Flammability and Explosibility

Not classified

Rhodium oxide(12036-35-0)Related Product Information

• Bismuth trioxide
• Lanthanum oxide
• Yttrium oxide
• Chromium(VI) oxide
• Sulfur trioxide
• Magnesium oxide
• Diantimony trioxide
• Rhodium
• COBALT(III) OXIDE BLACK
• Zinc oxide
• Zirconium dioxide
• ETHYLENE OXIDE
• Calcium oxide
• Phosphorus trioxide
• Boron oxide
• Iron oxide
• Dititanium trioxide
• NITRIC OXIDE