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Acid concentration Q's

  1. Jun 14, 2004 #1


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    Having some problems with the following question:

    Trimethylacetic acid [tex]C_4 H_{11} COOH[/tex]is a weak monoprotic acid. When 0.0010 mol of Trimethylacetic acid was dissolved in 100mL of water, the concentration of trimethylacetic ion was found to be [tex]3.0 \times 10^{ - 4} mol.L^{ - 1} [/tex]

    a) What is monoprotic acid?
    An Acid that donates only one proton.

    b) Use the above data to work out [tex]pK_a [/tex] for Trimethylacetic acid.
    now pKa = -log[Ka] think? How would I go about working Ka out?

    c) What volume of 0.2M KOH would be required to neutralise this solution of trimethylacetic acid?
    For this I would just work out how many moles are in the 100mL solution, and then use that to work out how how much volume of KOH I would need to add.
    However I'm unsure how to work out how many mols are in the 100mL solution, It's an easy units conversion problem im sure, but I suck at it :(
  2. jcsd
  3. Jun 14, 2004 #2
    Look at the concentration of the ion.

    If there's that much in the solution that exists as an ion, an equal amount must exist as H+.
  4. Jun 14, 2004 #3


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    Staff Emeritus
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    [tex]Ka= \frac {[H^+][A^-]} {[HA]}[/tex]


    [tex] [H^+] = 10^{-7} + [A^-][/tex]
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