I have recently seen a video of ruthenium on youtube. It says that ruthenium is invulnerable to many acids, especially aqua regia, but it gets destroyed by a simple household chemical, bleach. The video did not give a proper explanation about why this happens, it only gave the reaction mechanism. What is the reason for this Achilles' heel of ruthenium?
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asked Jul 14, 2015 at 14:06
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1$\begingroup$ What exactly are you asking? Are you looking for the thermodynamic reason why the reaction is favourable, the kinetic reason, or what? $\endgroup$– bonJul 14, 2015 at 20:42
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$\begingroup$ If I had to guess, it has to do with the fact that ruthenium oxide is much more soluble in base than in acid. $\endgroup$– Curt F.Jul 15, 2015 at 3:41
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$\begingroup$ Energetically favorable electronics? $\endgroup$– SendersReagentMar 29, 2016 at 17:51
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1 Answer
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This paper actually explain the reason for which ruthenium is vulnerable to bleach. Bleach actually contains $\ce{OCl^-}$ ions which acts as an oxidising agent and thus oxidises ruthenium. But the research on this phenomenon was done by using sodium hypochlorite, $\ce{NaOCl}$ in presence of a caustic alkali.
The experiment was done in two-fold process. First only using $\ce{NaOH}$ and the second using both $\ce{NaOCl}$ and $\ce{NaOH}$. In the first attempt, there was nothing occuring. The solutions with $\ce{NaOH}$ were stable for a considerable time, but after several weeks began to break down, giving a deposit of the black oxide. In the second process, when a little of hypochlorite was given, it gave a orange-red solution as you can see in the above video.
Some more attempts were made by repeating the experiments and found that concentrated alkali hypochlorite more or less dissolved any ruthenium present. From these experiments, the conclusions were made that ruthenium, is rather soluble in concentrated alkaline solutions of hypochlorites and this might help to distinguish ruthenium from other metals. The overall reaction of this process is(from the video):-
$$\ce{Ru + 3NaOCl + 2NaOH -> Na2RuO4 + 3NaCl + H2O}$$
$$\ce{Ru + 7NaOCl + 2NaOH -> 2NaRuO4 + 7NaCl + H2O}$$
$\ce{NaOCl -> 2NaCl + H2O}$ (ruthenate catalyzed)
$$\ce{Na2RuO4 + NaOCl + H2O-> RuO4 + NaCl + 2NaOH}$$
answered Mar 29, 2016 at 17:28
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$\begingroup$ There are no tables, but people do fake them $\endgroup$ Mar 29, 2016 at 19:45
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$\begingroup$ You can't make tables in mathjax. People do find workarounds, but nothing actually officially tabular. $\endgroup$ Mar 30, 2016 at 3:35