What does a weak acid titrated by its conjugate base look like?

[rocketbooster]

What does its titration curve look like? Is it just like the graph of a weak acid titrated with strong base?

I'm just curious because I'm thinking what its equivalent point would look like on the graph. The equivalent point is generally at the point where the weak acid has been fully neutralized by the strong base. It's the point where [HA initial]=[OH- of titrant base] or where the weak acid is at 0% and its conjugate base is at 100%.

In a weak acid titrated by its conjugate base, the [HA initial]=[OH- of titrant base] is at its half-equivalent point since that's where [HA]=[A-], and in this case [A-]=[OH- titrant base] IS the titrant base. Does this kind of graph not have a true half-equivalent or equivalent point or something? Wouldn't the equivalent point technically be where [HA]=2[OH- of titrant] since it should take 2 equivalents of conjugate base titrant to fully neutralize the initial weak acid? Why have I not seen this graph?

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[bjb305]

weak acid titrated with conjugate base = buffer

 

[rocketbooster]

weak acid titrated with conjugate base = buffer

yeah, I know that, but what about past the buffer?

In order to fully neutralize the weak acid, you would have to use 2 equivalents of its conjugate base, right?

 

[FIREitUP]

you don't titrate with weak reagents because they don't full react.

 

[Bernoull]

What does its titration curve look like? Is it just like the graph of a weak acid titrated with strong base?

I'm just curious because I'm thinking what its equivalent point would look like on the graph. The equivalent point is generally at the point where the weak acid has been fully neutralized by the strong base. It's the point where [HA initial]=[OH- of titrant base] or where the weak acid is at 0% and its conjugate base is at 100%.

In a weak acid titrated by its conjugate base, the [HA initial]=[OH- of titrant base] is at its half-equivalent point since that's where [HA]=[A-], and in this case [A-]=[OH- titrant base] IS the titrant base. Does this kind of graph not have a true half-equivalent or equivalent point or something? Wouldn't the equivalent point technically be where [HA]=2[OH- of titrant] since it should take 2 equivalents of conjugate base titrant to fully neutralize the initial weak acid? Why have I not seen this graph?

Very interesting questions!!!

Q.What does the titrating curve look like?
A. Is hard if not impossbile to say without numbers, pKb, pKa. Everyone knows the strong acids have weak conjugate bases and strong bases have weak converse holds. Too many student also falsely think that weak acids/bases have strong conjugates but this not necessarily true. Your weak acid could have a weak conjugate in which case ur curve will be that of a weak acid VS weak base, no vertical equivalence region, just a nearly flat region of inflexion.
If your acid is extremely weak then its acid dissociation equilibrium is way to the left implying a strong conjugate base therefore your titration curve is the usual weak acids strong base.

I do follow the logic of ur argument up until u discuss the 2moles of A- to neutralize 1 mole of HA. You have neutralization whenever u have equal moles of H+ and A- and this SHOULD be 1:1, 2:2 etc between HA and A- they should have the same "proticity" (i think this is a word..eehh..).
all u need is a*[A]*Va = b**Vb for neutralization. Also u will have neutralization irrespective of acid/base strength whenever u mix acids and bases.