[The Illuminati]

I hve a book(http://www.amazon.co.uk/Calculations.../dp/0582411270) that says that you can work out the pH and pKa from a titration curve.
It says all this stuff about how pKa and pH are equal and you need to half the volume...I have no idea what it means!
Help

[lamalas600]

Before you get the neutralisation point, adding aicd/alkali doesn't do much, as it is a buffer solution.
This also means that [HA]=[A-]
leaving Ka=[H+] in the acid equation
getting -logKa=-log[H+]
which is pka=pH

[The Illuminati]

(Original post by lamalas600)
Before you get the neutralisation point, adding aicd/alkali doesn't do much, as it is a buffer solution.
This also means that [HA]=[A-]
leaving Ka=[H+] in the acid equation
getting -logKa=-log[H+]
which is pka=pH

huh?

[lamalas600]

Maybe I'm awful at explaining... lol what don't you understand from that?

[The Illuminati]

Confusion number 1 how'd you know it's a buffer solution?

[lamalas600]

When you do a titration, there are no changes at all until a sudden colour change, this means that the pH isn't changing that much when your adding alkali/acid, until the neutralisation point.
Buffer - Resists changes in pH when small amounts of acid/alkali are added to it.

[The Illuminati]

(Original post by lamalas600)
When you do a titration, there are no changes at all until a sudden colour change, this means that the pH isn't changing that much when your adding alkali/acid, until the neutralisation point.
Buffer - Resists changes in pH when small amounts of acid/alkali are added to it.

So it acts as a buffer until the equivalence point (or is it the end point)?

[lamalas600]

(Original post by The Illuminati)
So it acts as a buffer until the equivalence point (or is it the end point)?

Yes, and equivalence point and end point are the same thing