1. Modern Chemistry Chapter 15 Acid-Base Titration and pH
Sections 1 & 2
Aqueous Solutions and the Concept of pH
Determining pH and Titrations
Chapter 15 Sec 1 The Concept of pH p

2. Aqueous Solutions and the Concept of pH
Chapter 15 Sec 1 The Concept of pH p

3. Chapter 15 Sec 1 The Concept of pH p. 499-510
Chapter 15 Vocabulary
Self Ionization pH
pOH
Acid-base indicator
Transition interval
Titration
Equivalence Point
Endpoint
Standard Solution
Primary Standard
Standardization
Chapter 15 Sec 1 The Concept of pH p

4. Self Ionization of Water
Two water molecules produce a hydronium ion and a hydroxide ion by transfer of a proton.
Water is a weak electrolyte.
H2O(l) + H2O(l)  H3O+(aq) + OH-(aq)
At 25C: [H3O+] = [OH-] = 1.0 x 10-7 M
Chapter 15 Sec 1 The Concept of pH p

5. Self Ionization of Water
BASE
ACID
ACID
BASE
[H3O+] = 1x10-7M
[OH-] = 1x10-7M
p.499
Chapter 15 Sec 1 The Concept of pH p

6. Ionization Constant for H2O
H2O(l) + H2O(l)  H3O+(aq) + OH-(aq)
The Keq for water = Kw = [H3O+] [OH-] 1
Kw = [H3O+] [OH-] = 1.0 x at 25C
This is the ionization constant for water.
Chapter 15 Sec 1 The Concept of pH p

7. H3O+ and OH- BASIC [H3O+] < [OH-] NEUTRAL [H3O+] = [OH-]
ACIDIC [H3O+] > [OH-]
H3O+
OH-
H3O+
OH-
OH-
H3O+
Chapter 15 Sec 1 The Concept of pH p

8. Calculating [H3O+] [OH-]
If [H3O+] is known then use
1.0 x = [H3O+] [OH-]
to get [OH-].
This works for strong and weak acids.
Chapter 15 Sec 1 The Concept of pH p

9. Chapter 15 Sec 1 The Concept of pH p. 499-510
Concentrations & Kw
Chapter 15 Sec 1 The Concept of pH p

10. Chapter 15 Sec 1 The Concept of pH p. 499-510
Sample Problems p.502
A 1.0 x 10–4 M solution of HNO3 has been prepared for a laboratory experiment.
Calculate the [H3O+] of this solution.
Calculate the [OH–].
a. 1.0 × 10−4 M H3O b. 1.0 × 10−10 M OH-
Chapter 15 Sec 1 The Concept of pH p

11. Chapter 15 Sec 1 The Concept of pH p. 499-510
Practice Problems p.502
1. Determine the hydronium and hydroxide ion concentrations in a solution that is 1 × 10−4 M HCl.
2. Determine the hydronium and hydroxide ion concentrations in a solution that is 1.0 × 10−3 M HNO3.
[H3O+] = 1 × 10−4 M; [OH−] = 1 × 10−10 M
[H3O+] = 1.0 × 10−3 M;[OH−] = 1.0 × 10−11 M
Chapter 15 Sec 1 The Concept of pH p

12. Chapter 15 Sec 1 The Concept of pH p. 499-510
Practice Problems p.502
3. Determine the hydronium and hydroxide ion concentrations in a solution that is 3.0 × 10−2 M NaOH.
4. Determine the hydronium and hydroxide ion concentrations in a solution that is 1.0 × 10−4 M Ca(OH)2.
[H3O+] = 3.3 × 10−13 M;[OH−] = 3.0 × 10−2 M
[H3O+] = 5.0 × 10−11 M;[OH−] = 2.0 × 10−4 M
Chapter 15 Sec 1 The Concept of pH p

13. Chapter 15 Sec 1 The Concept of pH p. 499-510
The pH Scale
pH – the negative of the common log of the hydronium ion concentration
Based on the hydrogen ion concentration.
Pouvoir hydrogéne (french) : hydrogen power
Scale of 0-14
<7 Acidic =7 Neutral >7Basic
Chapter 15 Sec 1 The Concept of pH p

14. pH = -log [H3O+] The pH Scale log 1.0 x 10 = 
What is the pH if [H3O+]= 1.0 x 10-12?
log 1.0 x = -12
- log 1.0 x = 12
Chapter 15 Sec 1 The Concept of pH p

15. Relationship of [H3O+] to [OH-] and pH
Chapter 15 Sec 1 The Concept of pH p

16. Chapter 15 Sec 1 The Concept of pH p. 499-510
The pH Scale
pH = -log [H3O+]
If 1.00 x = [H3O+] [OH-] what is the highest that [H3O+] can be?
1 x 10 0
pH=0
What is the lowest that [H3O+] can be?
1 x
pH=14
Chapter 15 Sec 1 The Concept of pH p

17. Chapter 15 Sec 1 The Concept of pH p. 499-510
pH Scale
p. 503
Chapter 15 Sec 1 The Concept of pH p

18. Chapter 15 Sec 1 The Concept of pH p. 499-510
The pH Scale
Chapter 15 Sec 1 The Concept of pH p

19. Chapter 15 Sec 1 The Concept of pH p. 499-510
pH of Common Materials
p. 504
Chapter 15 Sec 1 The Concept of pH p

20. Chapter 15 Sec 1 The Concept of pH p. 499-510
pH of Common Materials
p. 512
Chapter 15 Sec 1 The Concept of pH p

21. Chapter 15 Sec 1 The Concept of pH p. 499-510
pH = 4 = -log [H3O+]

pH = -log [2.3x10-8]
  [EE] 
Using Your Calculator
Chapter 15 Sec 1 The Concept of pH p

22. Chapter 15 Sec 1 The Concept of pH p. 499-510
Sample Problems p.505
What is the pH of a 1.0 x 10–3 M NaOH solution?
11.00
Chapter 15 Sec 1 The Concept of pH p

23. Chapter 15 Sec 1 The Concept of pH p. 499-510
Practice Problems p.505
Determine the pH of the following solutions:
a. 1 × 10−3 M HCl
b. 1.0 × 10−5 M HNO3
c. 1 × 10−4 M NaOH
d. 1.0 × 10−2 M KOH
a. pH = 3.0
b. pH = 5.00
c. pH = 10.0
d. pH = 12.00
Chapter 15 Sec 1 The Concept of pH p

24. Chapter 15 Sec 1 The Concept of pH p. 499-510
Sample Problems p.506
What is the pH of a solution if the [H3O+] is 3.4 x 10–5 M?
4.47
Chapter 15 Sec 1 The Concept of pH p

25. Chapter 15 Sec 1 The Concept of pH p. 499-510
Practice Problems p.506
1. What is the pH of a solution if the [H3O+] is 6.7 × 10−4 M?
2. What is the pH of a solution with a hydronium ion concentration of 2.5 × 10−2 M?
3. Determine the pH of a 2.5 × 10−6 M HNO3 solution.
4. Determine the pH of a 2.0 × 10−2 M Sr(OH)2 solution.
1. pH = 3.17
2. pH = 1.60
3. pH = 5.60
4. pH = 12.60
Chapter 15 Sec 1 The Concept of pH p

26. Chapter 15 Sec 1 The Concept of pH p. 499-510
Sample Problems p.507
Determine the hydronium ion concentration of an aqueous solution that has a pH of 4.0.
[H3O+] = 1 × 10−4 M
Chapter 15 Sec 1 The Concept of pH p

27. Chapter 15 Sec 1 The Concept of pH p. 499-510
Practice Problems p.508
1. The pH of a solution is determined to be 5.0.What is the hydronium ion concentration of this solution?
2. The pH of a solution is determined to be 12.0.What is the hydronium ion concentration of this solution?
[H3O+] = 1 × 10−5 M
[H3O+] = 1 × 10−12 M
Chapter 15 Sec 1 The Concept of pH p

28. Chapter 15 Sec 1 The Concept of pH p. 499-510
Practice Problems p.508
3. The pH of an aqueous solution is measured as Calculate the [H3O+] and the [OH−].
4. The pH of an aqueous solution is Determine [H3O+].
[H3O+] = 3.2 × 10−2 M; [OH−] = 3.2 × 10−13 M
[H3O+] = 2.1 × 10−4 M
Chapter 15 Sec 1 The Concept of pH p

29. Chapter 15 Sec 1 The Concept of pH p. 499-510
pOH
A scale based on the hydroxide ion concentration
0-14
<7 basic =7 neutral >7 acidic
Chapter 15 Sec 1 The Concept of pH p

30. Chapter 15 Sec 1 The Concept of pH p. 499-510
pOH and Hydroxide
Chapter 15 Sec 1 The Concept of pH p

31. [H3O+] for Strong & Weak Acids
For Strong Acids
HCl  H Cl-
0.10M M M
Use the mole ratio.
REVIEW
For Weak Acids
HF  H F-
0.10M <0.10M <0.10M
Use the “I.C.E.” or use equilibrium concentrations.
Chapter 15 Sec 1 The Concept of pH p

32. Calculating [H3O+] [OH-]
Ka= [negative ion] [H3O+]
[acid molarity] Ka Kw
Kw = 1.00 x = [H3O+] [OH-]
pH = -log [H3O+] pH
Chapter 15 Sec 1 The Concept of pH p

33. Calculating [H3O+] [OH-]Ka
[H3O+] . pH Kw
Chapter 15 Sec 1 The Concept of pH p

34. Chapter 15 Sec 1 The Concept of pH p. 499-510
Weak Acid Problems
Assume that enough lactic acid, CH3CHOHCOOH, is dissolved in sour milk to give a solution concentration of 0.10 M lactic acid. A pH meter show that the pH of the sour milk is Calculate the Ka for the equilibrium system. CH3CHOHCOOH  CH3CHOHCOO- + H+
1.44 x 10-4
Chapter 15 Sec 1 The Concept of pH p

35. Chapter 15 Sec 1 The Concept of pH p. 499-510
Weak Acid Problems
When the [HNO2] is 0.08M, the pH of the acid is 2.4 Calculate the Ka for the nitrous acid. HNO2+H2OH3O+ + NO2-
2.1 x 10-4
Chapter 15 Sec 1 The Concept of pH p

36. Chapter 15 Sec 1 The Concept of pH p. 499-510
Acid & Base Strength
Chapter 15 Sec 1 The Concept of pH p

37. Chapter 15 Sec 1 The Concept of pH p. 499-510
Ch 15 Sec 1 Homework
Calculating [H3O+], [OH-], Ka & pH
Worksheet
Chapter 15 Sec 1 The Concept of pH p

38. Antacids & Neutralization
Chapter 15 Sec 1 The Concept of pH p

39. Chapter 15 Sec 1 The Concept of pH p. 499-510
Ch 15 Sec 1 Homework
Page 509 # 1-6
Chapter 15 Sec 1 The Concept of pH p