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Chem 102

Practice Sheets

Buffers and Acid/Base Titrations

1. Determine if the following solutions can be classified as a buffer system.

a. NaClO₄/HClO₄          b. KH₂PO₄/K₂HPO₄

c. HCN/KCN                 d. HCl/KCl

2. Calculate the pH of a 0.20M acetic acid solution. What is the pH of a solution containing 0.20M CH₃COOH and 0.30M CH₃COONa? The Ka of CH₃COOH is 1.8x10^-5.

3. What is the pH of 0.30M solution of formic acid (HCOOH). What is the pH of a solution of 0.30M HCOOH and 0.52M HCOOK. The Ka of formic acid is 1.7x10^-4.

4.  How would you prepare a 1.0L acetate buffer with a pH of 6.1

5. How would you prepare a 500mL formate buffer with a pH of 4.6

6. How would you prepare a 2.0L oxalate (C₂O₄^-2) buffer with a pH of 4.88

7. How would you prepare a 200mL phosphate buffer with a pH of 7.6

Acid-Base Titrations

8. What is the pH of 25mL of a 0.10M solution of HCl? What will the pH be after adding each of 6 5mL aliquots of 0.10M NaOH. Draw a titration curve

9. What is the pH of 40mL of a 0.20M solution of HBr? What will the pH be after adding each of 5 10mL aliquots of 0.20M KOH? Sketch a titration curve.

10. Calculate the pH of a buffer system containing 1.0M acetic acid and 1.0M sodium acetate. What is the pH of the buffer system after the addition of 0.10 mole of gaseous HCl to 1.0L of this solution.

11. Calculate the pH of a 0.30M/0.36M NH₄Cl/NH₃ buffer system. What is the pH after the addition of 0.07 mole of gaseous HCl to 1500mL of this solution?

12. What is the pH of 30mL of a 0.15M acetic acid solution. What is the pH of the solution after 10, 20, 30, and 40mL of a 0.15M LiOH solution are? Sketch a titration curve.

13.  What is the pH of 25mL of an aqueous 0.50M NH₃ solution? What is the pH of the solution after 5, 10, 20, 25 and 40mL of a 0.50M solution of HI is added? Sketch a titration curve.