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Use the plots of BC and Alpha to convince yourself that the maximum buffer capacity corresponds to equal concentrations of conjugate acid and conjugate base, assuming a fixed total concentration of both.
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How close must the two pK values for a diprotic acid be to eliminate the minimum in BC?
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As the pH of a malonic acid solution is varied, at what pH does the HMal- species reach a maximum?
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Inspect the buffer capacity of a citric acid solution as a function of pH.  Also look at the alpha plots.  Over what pH range is citric acid a practical buffer system?
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Does the buffer capacity plot indicate that the first or the second endpoint in the titration of H3PO4 with NaOH is "sharpest?"
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Look at the buffer capacity and alpha plots for a hypothetical triprotic acid having pK1 4.00, with pK2 and pK3 as close to this as theoretical possible (0.6 log unit steps).
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See how weak a monoprotic acid would have to be in order for the buffer capacity minimum (at the NaOH titration endpoint) to just disappear.
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Figure out what 3 pK values for a triprotic acid would permit a titration curve to have 3 reasonable endpoints (i.e., best possible minima in buffer capacity).  Hint: Set pK1 at its lowest value.  Look at the alpha plots for this case:  do the intermediate species approach alpha values of unity?
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