Black purple shiny crystals or light purple granules or powder. Melting point 89℃; d25 1.83. Soluble in 4 parts of cold water and 2 parts of boiling water. Almost insoluble in ethanol. Easy to weather, ruby red under transmitted light, heated to 100℃ and loses part of the crystal water and turns green, dihydrate at 110℃, anhydrous at 400℃ and light yellow-green, and loses water solubility. Its aqueous solution is purple when cold and green when hot.

PREPARATION METHOD

Dissolve potassium dichromate in hot water and filter. Add concentrated sulfuric acid to the filtrate, and then gradually add ethanol. When the liquid turns dark green, continue to add ethanol until no more changes occur, that is, the end point of the reaction is reached. Evaporate the solution, add water to the relative density of the solution to 1.5, and then let it stand to crystallize. Filter out the crystals by suction and dry them thoroughly.

USES

Used as an analytical reagent. It is used as a film hardener in photographic fixer, a chromium complexing agent in the production of reactive red brown K-B3R, neutral purple BL, neutral orange RL and neutral pink BL, and a mordant in printing and dyeing. It is also used in glass, ceramics and other fields.