Rhodium Trioxide, RhO₃

Rhodium Trioxide, RhO₃, separates out as a blue precipitate from the solution left after preparing the dioxide, on neutralising the alkali with nitric acid. It dissolves in hydrochloric acid evolving chlorine, the trichloride remaining in solution:

2RhO₃ + 12HCl = 2RhCl₃ + 6H₂O + 3Cl₂.