[FouRRaW]

So the question is....

The strength of an acid plays no significant role in the method of titration.  The procedure will tell us the concentration of the acid regardless of its strength.  Explain why we will require just as much base to titrate a weak acid (such as CH₃COOH) as an equal volume of a strong acid having the same concentration, even though the weak acid at equilibrium is only partially dissociated, and contains a much lower [H³O⁺] .

My teachers analogy is that the problem is like... You go to the bank and you have $1000.  You could choose to withdraw it all at once.  Or you could choose to withdraw it in small amounts over a long period of time. 

So the only thing i can get out of it so far is that....  well actually I'm kind of confused but here's a start.
Attempt:  It doesn't matter wether the acid is weak or strong.  It only matters wether you put equal amounts of the titrant and the other substance.  I'm so lost can anyone give me a hint??  Is it that it just takes longer to titrate a weak acid??  Or is it that all the acid is there, it's just not as concentrated??

Is any of this correct?? Any hints??
Thanks and sorry for the long question

[mike]

Your teacher's analogy works.

Think of it this way: If you had one molecule of strong acid, like HCl, you would need one molecule of base, such as NaOH to neutralise it. If you had 1000 molecules of a strong acid like HCl, you would need 1000 molecules of a base like NaOH to neutralise it.

So now if you had 1 molecule of a weak acid like acetic acid, you will still need one molecule of base to neutralise it, and if you had 1000 molecules of acetic acid you will still need 1000 molecules of base to neutralise it.

Neutralise generally means you have equal amounts of acid and base.

Now the only difference between the strong acid and the weak acid is: with your strong acid like HCl, all 1000 of the H⁺ ions are already sitting in solution waiting around to be neutralised. In the acetic acid solution you may only have 50 out of the 1000 ions waiting to be neutralised, however as soon as those 50 are neutralised the acetic acid realises that there is a deficiency of H⁺ all of a sudden so another 50 ions are dissociated and then they get neutralised, and this continues on and on until the entire 1000 are used up.

So like your teachers bank analogy, it doesn't matter whether you neutralise all 1000 in one go or 50 at a time if you start with 1000 of either you will still have to neutralise 1000 by the end.

[FouRRaW]

Thank You so much, i think it's clear now, finally!
P.S. I like Nirvana too!

[Borek]

As usual, here comes Borek with his "Not so easy" rant

It doesn't matter if the acid is weak only to some degree - it can be weak, but it must be strong enough. If it is too weak, pH change at inflection point is too low to be measurable or applicable.

I am not going to post plots this time, but you may download my BATE, create solution containing acid and base of 0.01M concentrations, click on the "titration curves" button (enter any names for acid and base to make the button active) and play with changing pK_a1 to see how titration curve gets flat. Try pK_a1 = 9 - no way you can use titration to determine concentration of acid. Note, that HCN in water solution is even weaker - yet it is still considered to be a weak acid!