Chromium trioxide (chemical formula: CrO3), usually dark red, orthorhombic crystal, soluble in water, alcohol, sulfuric acid and ether, but insoluble in acetone (acetone will explode violently when encountering chromium trioxide, which is dangerous!), Deliquescent easily. Dissolve in water to form chromic acid. It has strong oxidizability. Chromium trioxide, sulfuric acid and acetone are used to oxidize alcohols to carboxylic acids or ketones (Jones oxidation reaction). Chromium trioxide can be precipitated by the reaction of sodium dichromate and concentrated sulfuric acid, so it has long been called chromic acid. It decomposes above 197 ° C and gradually loses oxygen. The intermediate product is black chromium dioxide and the final product is chromium trioxide. It can form adducts with many organic compounds (such as pyridine) with the general formula CrO3 · 2L.