This simulation shows the stepwise titration of a weak acid (AH) with a strong base to produce the anion (A^-). The pH recorded is plotted vs. the equivalents of OH^- added. The sizes of the symbols corresponds to the relative concentrations of AH and A^-.

Questions (you should be able to answer):
1. What is the pK_a of the weak acid in this titration?
2. If the starting solution were 100 ml of 0.05 M AH, what volume of 1.0 M NaOH was added at each point shown above?
3. At a ratio of AH : A^- = 3 : 1, what was the measured pH?
4. If this simulation corresponded to the titration of a phosphate salt, write the chemical structures that correspond to AH and A^-
. What are the other chemical species that participate in the reaction?

Back to Lecture 3: Acid-Base Equilibria & Buffers.

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