1. Chapter 19: Acids and Bases

2. I. Acids and Bases - properties
Arrhenius theory
Acids, bases, and salts break down in H2O
Theory: acids produce H+ ions (protons)
bases produce OH- ions (hydroxides)

3. I. Acids and Bases - properties
BrØnstad-Lowry theory
Any donor of H+= acid; any acceptor = base
Ex: HCl + H2O H3O+ + Cl-
acid base hydronium
Acid + Base Conjugate Acid + Conj. Base
Ex: NH3 + H2O NH4+ + OH-
base acid conj. acid conj. base

4. I. Acids and Bases - properties
Amphoterics – compounds that sometimes act as acids, sometimes as bases
Ex: HCl + H2O  H3O+ + Cl-
NH3 + H2O  NH4+ + OH-

5. I. Acids and Bases - properties
Acidic & basic anhydrides (w/o water)
Acidic anhydride = oxide producing acid w/ water
SO2 + H2O  H2SO3
Basic anhydride = oxide producing base w/ water
Na2O + H2O  2 NaOH

6. I. Acids and Bases - properties
Acid/base strength
Acids that ionize completely into + and – ions = strong acid (pH of 0 – 2)
Bases that ionize completely into + and – ions = strong base (pH of 12 – 14)
Weak acid/base = pH 2.1 – 6.9; 7.1 – 11.9
Neutral = pH of 7

7. A quick look at water… H2O - amphoteric Sometimes loses H+  OH-
Sometimes gains H+  H3O+ (hydronium ion)

8. Acid/Base problems
Chapter 19 (3, 4, 6, 8, 53, 56, 57, 84, 85, 88, 89)

9. Neutralization reactions
H3PO4 + NaOH  H2O + Na3PO4
H2SO4 + Ba(OH)2  H2O + BaSO4
HCl + KOH  H2O + KCl
HNO3 + Ca(OH)2  H2O + Ca(NO3)2
#H+ ions X Macid X Vol acid = #OH- ions X Mbase X Volbase
(Your book will have you balance the equations and run mole ratios instead of the above method, so beginning problems will look different)

10. Neutralization calculation example
How many mL of 8 M H2SO4 is needed to neutralize 750 mL of 12 M NaOH?
Known: 2 H+, 1 OH-
(2) (8) (X) = 1 (750 mL) (12)
X = mL
.25 L of 5 M H3PO4 is used to neutralize 1.5L of Ba(OH)2. What is the concentration of the base?
Known: 3 H+, 2 OH-
(3) (5) (.25L) = (2) (X) (1.5L)
X = 1.25 M

11. Homework:
P. 673 (35-38, 41, 73)
This will take you about 15 minutes!

12. Acidic vs. Basic solutions
Acid = more [H+] than [OH-]; acidic
[H+] > 1.0 x 10-7
Base = fewer [H+] than [OH-]; alkaline
[H+] < 1.0 x 10-7
[H+] X [OH-] = 1.0 X 10-14
Ex: If [H+] = 1.0 x 10-5M, is it an acid, base, or neutral? What is the [OH-] of solution?

13. Ex: If [H+] = 1. 0 x 10-5M, is it an acid, base, or neutral
Ex: If [H+] = 1.0 x 10-5M, is it an acid, base, or neutral? What is the [OH-] of solution?
Acidic, since 10-5 > 10-7

14. Ex: If [H+] = 1. 0 x 10-5M, is it an acid, base, or neutral
Ex: If [H+] = 1.0 x 10-5M, is it an acid, base, or neutral? What is the [OH-] of solution?
Known: [H+] x [OH-] = 1.0 x 10-14
[OH-] = 1.0 x / 1.0 x 10-5 = 1.0 x 10-9

15. [ ] Homework:
P. 655 (10 & 11)

16. pH Concept pH = - log [H+] Example: H2O is neutral
[H+] = 1 x 10-7M; ph = 7.0
pH = - log (1 x 10-7)
= - (log 1 + log 10-7)  log 10x
= - (0.0 + (-7.0))
= 7.0
These two are opposites of each other

17. pH Concept
Question: What is the pH of a solution with a [H+] of 1 x 10-4 M?
pH = - log (1 x 10-4)
= - (log 1 + log 10-4)
= - (0.0 + (-4))
= 4.0

18. pH Concept
Ex: What is the pH of a solution with a [H+] of 1.0 x 10-10?
pH = - log [H+]
= - log (1.0 x 10-10)
= - (log 1 + log 10-10)
= - (0.0 + (-10.00))
= 10

19. pH Concept Ex: What is the pH of a solution with a [H+] of 2.7 x 10-8?
pH = - log (2.7 X 10-8)
= - ( log log 10x 8-)
= - ( (-8))
= 7.56 pH

20. pH Concept Ex: What is the pH of a solution that is .0050 M [H+]?
Convert to scientific notation 1st! = 5.0 x 10-3
pH = - (log 5 + log 10-3)
= - ( log 5 + log 10x 3-)
= - ( (-3))
= 2.30 pH

21. pH Concept The pH of a solution is 6. What is the [H+]?
- log [H+] = pH 6
(switch signs!)
log [H+] =
antilog = 10x (– 6.00) =
= 1 x 10-6 [H+]

22. pH Concept What is the [H+] if the pH is 3.70? - log [H+] = pH 3.70
antilog = 10x (– 3.70) =
= 2.00 x 10-4

23. pH Problems
P. 657 (12-17, 22, 24, 63-65, 86)

24. pOH Concept pOH = - log [OH-] pH + pOH = 14 pH = 14 – pOH
Also recall: [H+] X [OH-] = 1.0 X 10-14

25. pH 14 - _ pOH [H+] [OH-] pH = -log [H+] pOH = -log [OH-]
[H+] X [OH-] = 1 X 10-14
[OH-]

26. pOH Concept Ex: What is the pH if [OH-] = 4.0 x 10-11M?
pH = 1 x 10-14/ 4 x 10-11 =
= 2.5 x 10-4M

27. pOH Concept Ex: What is the [OH-] if the pOH is 11.22?
log [OH-] = 11.22
log [OH-] =
[OH-] = antilog x
= 6.03 X 10-12

28. Last one!
What is the [H+] if the pOH is 2.38?

29. A Quick Review…
Arrhenius acids/bases – H+ or OH-
BrØnstad-Lowry – H+ donated or accepted
Anhydrides – add water!
If OH, base; if H, acid
MgO SO2
ZnO K2O CO2
Neutralizations:
#H+ ions X Macid X Vol acid = #OH- ions X Mbase X Volbase
pH, pOH, [H+], [OH-]pH Calculations