Ruthenium

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Ruthenium is one of the platinum group metals (PGM). It is a steel white metal with a melting point of 2334 °C (4233 °F). Ruthenium is found as a minor component in platinum ores and most of it is used in thin film resistors in electronics and in wear-resistant electric connectors. Some is used as an alloying element in platinum alloys and some in chemical catalysts.

WARNING!

Ruthenium is similar to osmium that it can assume oxidation state 8+ and can form a volatile tetroxide that reacts with biological matters, attacking lungs and eyes irreversible. Any reaction that can form ruthenium tetroxide must be done in a suitable fume hood.

Contents

Chemical reactions

Ruthenium is very resistant against all acids, even aqua regia. It can be dissolved in fused alkalis giving RuO22-, ruthenates. It is also attacked by halogens at high temperature.

Occurs in

Ruthenium compounds

Ruthenium dioxide

RuO2 is a bluish black solid and is usually formed by heating ruthenium in air at 1000 °C. It can also form from other ruthenium compounds, for example ruthenium compounds oxidized by nitric acid.

Ruthenium tetroxide

A volatile and extremely toxic substance. In air it will attack your eyes, depositing ruthenium in the cornea and blocking out light. When inhaled it attacks the lungs.

Ruthenium tetroxide melts at 25.4 °C (77.7 °F) and boils at 40.0 °C (104.0 °F). It is possible to distill in air. Heated above 100°C it will explode and form RuO2.

Note : There seems to be several different boiling points reported in the literature.

Melting ruthenium

If ruthenium is melted in a carbon crucible it will dissolve quite a lot of carbon and the melting point will be lowered. When solidifying the carbon is expelled as small graphite flakes within the metal. Ruthenium must be melted in an inert atmosphere or under vacuum to not form volatile oxides.

Refining ruthenium

Ruthenium is oxidized into ruthenium tetroxide (RuO4), distilled and then turned into (NH4)3RuCl6. The pure metal is recovered as a metal sponge by igniting the salt in a hydrogen atmosphere.

WARNING!

Ruthenium tetroxide can detonate if heated to 109 C.

References

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