Ruthenium

Ruthenium reacts very little oxygen, O₂, under normal conditions. If heated, ruthenium is oxidized to Ru(IV) oxide:

Ru(s) + O₂(g) RuO₂(s)

Ruthenium will react with excess F₂, forming ruthenium(VI) fluoride, RuF₆.

Ru(s) + 3 F₂(g) RuF₆(s) [dark brown]


When heating to 330 °C, ruthenium will react with chlorine, Cl₂, in the presence of carbon monoxide, CO, forming a dark brown ruthenium(III) chloride, RuCl₃. Additional heating of the material, in the presence of Cl₂, gives a black form of ruthenium(III) chloride.

2 Ru(s) + 3 Cl₂(g) 2 RuCl₃(s)

Ruthenium reacts with water [1]:

Ru²⁺(aq) + 2 H₂O(l) RuO₂(s) + 4 H⁺(aq) + 2 e⁻             E° = -1.120 V
RuO₂(s) + 2 H₂O(l) RuO₄(s) + 4 H⁺(aq) + 4 e⁻             E° = -1.387 V
Ru²⁺(aq) + 4 H₂O(l) RuO₄²⁻(aq) + 8 H⁺(aq) + 4 e⁻        E° = -1.563 V
Ru²⁺(aq) + 4 H₂O(l) RuO₄⁻(aq) + 8 H⁺(aq) + 5 e⁻         E° = -1.368 V