1. Unit 6: Acid-Base Applications Lesson 5: Titration of a Weak Base with a Strong Acid

2. Titration Curve (Weak Base + Strong Acid)
Like the curve for a strong base and a weak acid, but upside down!
pH < 7 at eq point.
10 min

3. Choosing an Indicator Weak Base + Strong Acid → Acidic Salt
E.g. NH3 + HCl → NH4+ + Cl-
Thus the eq point is acidic. The weaker the base, the stronger its conjugate acid, and the lower the pH of the equivalence point!
In general, choose an indicator with pKa = 4-6
10 min

4. Brain Break! Find as many words as you can using the letters shown, always using the middle letter. What’s the 9-letter word?
translate

5. Finding [Base] without [Acid]
Step 1: pKb = pOH1/2 Step 2: [A-]eq = [OH-]init2 / Kb Step 3: [A-]init = [A-]eq + [OH-]init Example: A mL sample of ethylamine (a weak base) is titrated with mL of HCl. The initial pH of the ethylamine sample is , and the pH after 9.60 mL of HCl has been added is Find the initial concentration of ethylamine.
20 min

6. Practice:
Pg. 176 #125, 127, and 130
15 min