Rhodium Dioxide, RhO₂

Rhodium Dioxide, RhO₂, results in the anhydrous state on fusing a mixture of rhodium and potassium hydroxide and nitrate in a crucible heated to redness. The product is washed with water, then with hydrochloric acid, and finally dried at 100° C. in an inert gas such as carbon dioxide. It is a brown powder, insoluble in acids, in aqua regia, and even in boiling alkalies.