Chemical Properties of Ruthenium

Chemical Properties of Ruthenium are mainly related with its metallic properties. When heated in air ruthenium becomes covered with a brown film of oxide and, on cooling, "spits" in a similar manner to iridium and silver. Heated in oxygen, particularly when in a fine state of division, it yields the dioxide, RuO₂, and at 600° C. some tetroxide, RuO₄, begins to be formed. Previous ignition in hydrogen to a high temperature reduces the velocity of oxidation of ruthenium. Mineral acids have no action upon ruthenium, and aqua regia only slowly dissolves it.

When heated in fluorine a volatile fluoride is formed, and in chlorine a chloride is obtained, possibly the dichloride, RuCl₂. Ignition with potassium chloride in a current of chlorine yields potassium chlor- ruthenate, which is soluble in water.

Alkali hypochlorites effect the solution of ruthenium when fused, but the best mixture to employ consists of potassium hydroxide and nitrate, a green mass of potassium ruthenate, K₂RuO₄, being formed. This dissolves in water to an orange-coloured solution, which leaves a black stain upon the skin.

Fusion with potassium hydrogen sulphate is without effect upon ruthenium, although in like circumstances rhodium, palladium, and iridium are attacked.