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Acid-Base Titrations (McGuire)

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    Monoprotic Titrations

    Examine the following titration curves for the next 3 questions:                      

    TitrationCurves_Monoprotic.png

    1. Which one of the titration curves corresponds to the titration of a weak acid (in flask) with a strong base (in buret)?

     

     

     

     

    1. Consider titration (b). What was the original concentration of the acid or base in the flask if the original volume was 100 mL and it was titrated with a standard solution (in buret) that had a concentration of 0.100 M?

     

     

     

     

     

     

     

    1. Consider the titration curve that corresponds to the titration of a weak base with a strong acid. From the data shown, what is the approximate Kb of the weak base?

     

     

     

     

     

     

    Consider the following titration for the next 5 questions.

    20.0 mL of 0.060 M HClO4 (in the flask) is titrated with 0.040 M NaOH (in buret).

    1. What is the overall reaction occurring in the titration?

     

     

     

     

    1. How many mL of the NaOH solution need to be added to reach the equivalence point of the titration?

     

     

     

     

     

     

    1. Which of the following is present in the flask after some NaOH has been added, but before the equivalence point has been reached? Mark all correct answers.

      (a) HClO4(aq)       (b) NaOH(aq)        (c) NaClO4(aq)          (d) NaClO3(aq)

     

    1. Which of the following is present in the flask at the equivalence point of the titration? Mark all correct answers.

      (a) HClO4(aq)       (b) NaOH(aq)        (c) NaClO4(aq)          (d) NaClO3(aq)

     

    1. What is the pH of the solution in the flask at the equivalence point of the titration?









     

    Consider the following titration for the next 4 questions.

    20.0 mL of 0.060 M piperidine, C5H11N (pKa = 11.125), is titrated with 0.040 M HClO4.

    1. What is the overall reaction occurring in the titration?

     

     

     

     

     

     

     

    1. What is the pH of the solution in the flask after 5.00 mL of the HClO4 have been added?

















     

    1. What is the pH at the equivalence point of the titration?















     

    1. What is the pH of the solution in the flask after 35.00 mL of the HClO4 have been added?













     

    Consider the following titration for the next 4 questions:

    30.0 mL of a 0.100 M HF (pKa = 3.17) solution is titrated with a 0.200 M NaOH solution.

    1. How many mL of the NaOH solution needs to be added to reach the equivalence point of the titration?









     

    1. What is the pH of the solution after 5.00 mL of the NaOH solution has been added?









     

    1. What is the pH of the solution at the equivalence point of the titration?










     

    1. What is the pH of the solution after 18.00 mL of the NaOH solution has been added?











     

     

    Polyprotic Titrations

    When 100.0mL of 0.10M malonic acid is titrated with 0.10M NaOH the following titration curve is observed:

    TitrationCurve_MalonicAcid.png

    Given that Kal = 1.5 x 10-3 and Ka2= 2.0 x 10-6 for malonic acid, find the pH at each of the labelled points.

    1) point A:


     


     

     










     

    2) point B:





     

     

     








     

    3) point C:















     

    4) point D:
















     

    5) point E:















     

    25.0 mL of a 0.10 M solution of a weak base (pKb1 = 4.50 and pKb2 = 7.24) is titrated with 0.10 M HCl and the following titration curve is observed.  Calculate the pH at each of the marked points.

    TitrationCurve_WeakBase.png

    6) point A:










     

    7) point B:











     

    8) point C:













     

    9) point D:
















     

    10) point E:















     

    11) point F:










     

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