Impure chromium trioxide
| IUPAC name
| Other names
Chromic acid anhydride
|Molar mass||99.99 g/mol|
|Appearance||Dark red solid|
|Density||2.7 g/cm3 (at 20 °C)|
|Melting point||197 °C (387 °F; 470 K)|
|Boiling point||250 °C (482 °F; 523 K) (decomposes)|
| 164.8 g/100 mL (0 °C)|
169 g/100 mL (25 °C)
172.6 g/100 mL (40 °C)
198.1 g/100 mL (100 °C)
|Solubility||Soluble in acetic acid, acetone, diethyl ether, nitric acid, sulfuric acid|
|Vapor pressure||~0 mmHg|
Std enthalpy of
|Safety data sheet||ScienceLab|
|Lethal dose or concentration (LD, LC):|
LD50 (Median dose)
|80 mg/kg (rats, oral)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Chromium trioxide is an inorganic compound with the formula CrO3. It is a dark red/crimson solid, widely used in synthesis and industry. It is the acidic anhydride of chromic acid.
Chromium trioxide reacts violently with ethanol and other organic compounds, causing it to combust.
Chromium trioxide is a dard red/crimson solid in its anhydrous form, and red-orange in aqueous solution. It is very soluble in water and soluble in some organic solvents, such as acetone or diethyl ether, as well as sulfuric acid.
Chromium trioxide is sold by various chemical suppliers, though due to its hazards it's not easy to get hold of.
- H2SO4 + Na2CrO4 → CrO3 + Na2SO4 + H2O
- H2SO4 + Na2Cr2O7 → 2 CrO3 + Na2SO4 + H2O
The solid compound is filtered using a fritted funnel.
- Chrome plating
- Instantaneous ignition of alcohols
Chromium trioxide is a powerful oxidizer, highly toxic, corrosive, and carcinogenic. Avoid contact with alcohols.
Chromium trioxide should be kept in plastic or glass containers, with a proper label and a hazard symbol, in a dry place. If you're using glass, a good idea would be to keep the glass container inside a plastic container.
Since the compound ignites alcohols on contact, keep it away from any source of volatile solvents or products containing alcohols.