[bugsmenot]

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??

[Albert]

Do you think there is any difference between H⁺(aq) and H₃O⁺(aq)?

[bugsmenot]

...im probably being really stupid.

does the H3O then dissotiate to form another H+ and water?

[xiankai]

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.

[Borek]

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⁺...

[bugsmenot]

excelnt thats c leared thiings up thanks a lot guys