Titration calculations for strong/weak acid/base

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Titration calculations for strong/weak acid/base

Postby Chem_Mod » Sun Aug 21, 2011 12:52 pm

Question: In titrating a strong acid and a strong base, we use the pure concentrations and subtract OH concentration from H30 concentration and take the -log of the H30 concentration to get the pH. Conversely, when titrating weak acids and weak bases, we do the same steps, however we follow those calculations with an "ICE" chart and then take the -log of the equilibrium concentration. Is this generalization correct?

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Re: Titration calculations for strong/weak acid/base

Postby Chem_Mod » Sun Aug 21, 2011 12:53 pm

Answer: The 1st example is correct, provided [H3O+] > [OH-]. If not then subtract [H3O+] from [OH-] and take the -log to get pOH. Then use pH + pOH = 14 obtain pH.
For a titration involving a weak acid or base one has to set up an equilibrium table (ICE) to obtain [OH-] or [H3O+].


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