# Assignment A Lecture #3 Spring 2017

Henderson Hasselbalch Practice Problems

1. Calculate the relative amounts of acetate and acetic acid present at the following points when 1.0 mole of acetic acid is titrated with NaOH
a. 0.10 mole of NaOH added – ANSWER ratio = 0.1(acetate)/0.9 (acetic acid),
b. 0.30 mole of NaOH added – ANSWER = ratio = 0.3/0.7
c. 0.50 mole of NaOH added – ANSWER = ratio = 0.5/0.5
d. 0.70 mole of NaOH added – ANSWER = ratio = 0.7/0.3
e. 0.90 mole of NaOH added – ANSWER = ratio = 0.9/0.1

2. Calculate the pH of a solution obtained by adding 0.0063 mole of NaH2PO4 and 0.0100 mole of NaHPO4 to 100 mL of pure water. The pKa of NaH2PO4 is 7.2.

3. Calculate the pH of the solution obtained when
1.0 mL of 0.10 M HCl is added to 99.0 mL of pure water – ANSWER = 3.0
1.0 mL of 0.10 M NaOH is added to 99.0 mL of pure water – ANSWER = 11

4. Calculate the pH of the solution obtained by addition of 1.0 mL of 0.1 M HCl to 99 mL of buffer solution containing 0.0063 moles NaH2PO4and 0.0100 moles Na2HPO4

Download worked out problems HERE