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Working out pKa from titration curve graph

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    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!
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    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
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    (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
    :eek: huh?
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    Maybe I'm awful at explaining... lol what don't you understand from that?
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    Confusion number 1 how'd you know it's a buffer solution?
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    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.
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    (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)?
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    (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

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Updated: June 12, 2012
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