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Offline Quantumcat

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« on: 02/01/2004 23:44:42 »
My chem teacher in france uses this a lot and I have no idea what it is

Can someone explain it to me, how it forms what keeps it together etc. my chem teacher is australia never used it in anything. Thanks.

Also can someone explain exactly how acidobasic reactions work, the teacher said it's like oxydoreduction but with protons instead of neutrons? The teacher is really stupid he gives us the partners but doesn't explain what happens in the reaction. When he explained oxydoreduction he said nothing about reactivity. The students don't understand how or why it happens. In Australia we did oxydoreduction so i had background for that but not for acidobasic reactions. If someone explained what and how it happens I'd be really grateful :( I understand nothing.

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« Last Edit: 05/03/2004 04:14:42 by NakedScientist »


Offline Ylide

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Re: H3O
« Reply #1 on: 03/01/2004 09:22:55 »
H30 (which properly is presented as a postive ion H30+) is called hydronium.  It follows a certain acid-base theory (Arrhenius i think) that when an acidic compound loses a proton in water, that proton forms a complex with a water molecule (H20) called hydronium.  While not exactly correct, it's a decent way to think about it as the stoichiometry still works out in a neutralization reaction where the hydronium reacts with a hydroxide forming water.

 If you were to think of it as a free proton, you would only get 1 molecule of water.  If you were to think of it as hydronium, you'd get 2.

H+ + OH- -> H20
H30+ + OH- -> 2H20

Got it?  

In actuality, what happens is somewhere in between.  Protons dissociate from acids in aqueous solution, but then the free electron pairs in the oxygen molecules of water are attracted to the positive hydrogen atoms, basically hydrogen bonding.  (Which is a lecture for another day, I could talk for a while on the coolness that is hydrogen bonding)

Remember that acids dissociate in water to form a proton and an anion.  For instance, HCl(aq) -> H+ + Cl-
Strong acids dissociate 100% in water, weak acids do so only partially.

So in summary, when your teacher uses H30+ in a reaction, he means an acidic hydrogen, presumably from an acid that has been introduced into water.  H30+ loses that hydrogen (H+) to a base and becomes water.  (H20)  Incidentally, you can write the reaction for the formation for hydronium as
H20 + H+ -> H30+

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