Uranium Tetra-iodide, UI₄

Uranium Tetra-iodide, Uranous Iodide, UI₄, is obtained by passing iodine vapour over powdered uranium heated to 500° C. in a vacuum tube. It forms as a sublimate consisting of fine black needle- shaped crystals, of density 5.6 at 15° C. On heating, it melts at about 500° C., and in air readily oxidises to urano-uranic oxide. It is reduced when heated in hydrogen. It is soluble in water, yielding a green acid solution which gives the characteristic reactions of uranous salts and, like the solutions of the corresponding chloride and bromide, is unstable.