1. Titrations pH Titrant volume, mL
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2. Acid-Base Titrations
Adding NaOH from the buret to acetic acid in the flask, a weak acid. In the beginning the pH increases very slowly.

3. Acid-Base Titrations
Additional NaOH is added. pH rises as equivalence point is approached.

4. Acid-Base Titrations
Additional NaOH is added. pH increases and then levels off as NaOH is added beyond the equivalence point.

5. pH of solution of benzoic acid, a weak acid
QUESTION: You titrate 100. mL of a M solution of benzoic acid with M NaOH to the equivalence point. What is the pH of the final solution?
Equivalence point
pH of solution of benzoic acid, a weak acid

6. Acid-Base Reactions EQUILIBRIUM PORTION
QUESTION: You titrate 100. mL of a M solution of benzoic acid with M NaOH to the equivalence point. What is the pH of the final solution?
EQUILIBRIUM PORTION
Bz- + H2O HBz + OH Kb = 1.6 x 10-10
[Bz-] [HBz] [OH-]
equilib x x x
Solving in the usual way, we find
x = [OH-] = 1.8 x 10-6, pOH = 5.75, and pH = 8.25

7. QUESTION: You titrate 100. mL of a 0
QUESTION: You titrate 100. mL of a M solution of benzoic acid with M NaOH to the equivalence point. What is the pH of the final solution?
Half-way point

8. Acid-Base Reactions pH = 4.20
QUESTION: You titrate 100. mL of a M solution of benzoic acid with M NaOH What is the pH at the half-way point?
HBz + H2O H3O+ + Bz Ka = 6.3 x 10-5
[H3O+] = { [HBz] / [Bz-] } Ka
At the half-way point, [HBz] = [Bz-], so
[H3O+] = Ka = 6.3 x 10-5
pH = 4.20