1. Unit 6: Acid-Base Applications Lesson 4: Titration of a Weak Acid with a Strong Base

2. Titration Curve (Weak Acid + Strong Base)
Initial upswing in pH
At the half-eq point, the volume of base is half that required to reach the eq point, and the pH is half the eq point pH
Eq point has pH > 7
10 min

3. Choosing an Indicator Weak Acid + Strong Base → Basic Salt + Water
E.g. CH3COOH + NaOH → Na+ + CH3COO- + H2O
Thus the eq point is basic. The weaker the acid, the stronger its conjugate base and the higher the pH of the equivalence point!
In general, choose an indicator with pKa = 8-10
10 min

4. Finding [Acid] from [Base]
Normal titration calculation:
[OH-] x VB = mol OH-
mol OH- x unknown/known = mol HA
mol HA / VA = [HA]
5 min

5. Brain Break. Three circles, three related words
Brain Break! Three circles, three related words. Find the missing letter and unscramble the words.
I – kitten, whiskers, purring

6. Finding [Acid] without [Base]
Step 1: pKa = pH1/2 Step 2: [HA]eq = [H3O+]init2 / Ka Step 3: [HA]init = [HA]eq + [H3O+]init Example: A 25.0 mL solution of furoic acid, (C4H3O)COOH, is titrated with 28.8 mL of NaOH. The initial pH is and the pH when 14.4 mL of NaOH has been added is Find the initial concentration of furoic acid.
20 min

7. Practice:
Pg. 176 #126 and 129