Chemical Forums
Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: bugsmenot on August 23, 2006, 05:34:06 AM
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I am studying the reaction between acid and magnesium at A level.
As far as i was previously aware, the reaction is like this:
Mg(s) + 2H+(aq) ? Mg2+ (aq) + H2(g)
with the H+ coming from the acid.
the acid in this case is HCl so i would assume this is happening to get the H+:
HCl --> H+ + Cl-
However, the acid is diluted so apparantly, this occurs instead:
H2O(l) + HC l(g) --> H3O+ (aq) + Cl-(aq)
If this is the case, then what is the reaction between this d :-Xiluted acid and magnesium??
is a H+ involved?? what happens to this hydroxonium ion??
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Do you think there is any difference between H+(aq) and H3O+(aq)?
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...im probably being really stupid.
does the H3O then dissotiate to form another H+ and water?
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H+ is a theoretical ion, because its a free proton, which is WAYYYY too reactive and does not really exist for any appreciable time when it is in a environment with lots of mean water molecules waiting to collide with it.
therefore when acids dissociate in water, H+ is produced, but it quickly attaches itself to a water molecule forming H3O+.
but when writing reactions, it does not really matter whether u write H+ or H3O+, because for balancing purposes, you cancel the water on both sides of the equation:
H3O+ + OH- --> 2H2O
more or less the same as
H+ + OH- --> H2O
this is to say, the water molecule that the proton is attached to does not react or anything, but is a spectator molecule.
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H+ is a theoretical ion, because its a free proton, which is WAYYYY too reactive and does not really exist for any appreciable time when it is in a environment with lots of mean water molecules waiting to collide with it.
Note that H3O+ is probably kind of simplification too, as IIRC experimental evidence shows that ions present in the solution are more complicated - something like H5O2+ or H7O3+ or even H9O4+...
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excelnt thats c leared thiings up thanks a lot guys