I saw that all the oxyacids are strong oxidizing agent. I don't know why all the oxyacids are strong oxidizing agents? What is the reason?
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9$\begingroup$ That's at best an oversimplification. Yes things like nitric, perchloric, and sulphuric are thermodynamically strong oxidising agents, if sometimes kinetically slow. But then you have perrhenic acid, which is at best a weak oxidising agent, carbonic acid which I don't think I've ever though about in a redox context, and "sulphurous acid" (if it exists) which is normally though of as a reducing agent. $\endgroup$– Ian BushCommented Dec 2, 2015 at 8:38
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2 Answers
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Your premise is incorrect. Some oxyacids are oxidising agents. Some are not. Take e.g. carbonic acid. You cannot oxidise anything with carbonic acid, really.
Also, the choice of words is bad. Sulphurous acid (or hydrogen sulphonic acid; it doesn’t really make a difference; both are structural isomers) is also an oxyacid ($\ce{H2SO3}$) however it is a pretty good reducing agent oxidising itself to sulphuric acid. Heck, technically $\ce{H4SiO4}$ is an oxyacid, too, but it won’t oxidise anything at all.
So reducing the question to where it is correct we arrive at:
Why are some oxyacids where the central atom is in its highest possible oxidation state strong oxidising agents?
And it basically answers itself. Depending on the electronegativity of the central atom it will be more or less ‘happy’ to cede all its valence electrons to oxygens and be the centre of an oxyacid. For those that don’t like that lot in life, most notably nitric acid, they will often find species whose electrons they can take back (the atoms are electronegative after all) and thus oxidise them.
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2$\begingroup$ Please leave my British ph, @ortho ;) $\endgroup$– JanCommented Dec 3, 2015 at 18:57
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$\begingroup$ It is not about British or American. nature.com/nchem/journal/v1/n5/full/nchem.301.html old.iupac.org/publications/books/rbook/Red_Book_2005.pdf $\endgroup$ Commented Dec 3, 2015 at 19:01
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$\begingroup$ @orthocresol (I'll admit, I hadn’t rolled back if you hadn’t incorrectly assumed the wrong thing about sulphonic.) $\endgroup$– JanCommented Dec 3, 2015 at 19:04
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$\begingroup$ Yeah, it seems I assumed wrongly. $\endgroup$ Commented Dec 3, 2015 at 19:19
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Oxidising agents are those which take electron from others. Let us take a example of oxyacid say chloric acid that is HClO4 .In this compound the oxidation state of chlorine is +7 which is not highly favourable for chlorine because it is a halogen and will tend to gain electron. Moreover here chlorine has +7 oxidation state so it will have more affinity for electron so it will oxidise other compound to take electron . That's why oxyacids are strong oxidising agents.
answered Dec 2, 2015 at 20:55