1. Chapters 14 & 15: Acids and Bases
Modern Chemistry

2. What are acids and bases?
Special types of solutions with specific properties

3. Properties of acids and bases
Electrolytes
Sour taste
Produce hydrogen gas when react with metal
Corrosive
React with a base to make salt + water (called neutralization)
Turn litmus red
Phenolphthalein - clear
Electrolytes
Bitter taste
Slippery
Caustic
React with acid to make salt + water (called neutralization)
Turn litmus blue
Phenolphthalein - pink
ACIDS
BASES

4. Metal & Acid
Ba(s) + H2SO4(aq) BaSO4(s) + H2(g)
H2(g) is released

5. Common Bases
Sodium Hydroxide
Ammonia
Aluminum Hydroxide

6. Common acids
Sulfuric
Nitric
Phosphoric
Acetic
Hydrochloric

8. Acid Nomenclature
Binary acid – contains only two different elements. Ex.) HCl, HF, HBr
1. The name begins with hydro-.
2. The root of the name of the second element follows.
3. The name then ends with the suffix –ic.

9. Acid Nomenclature (cont.)
Oxyacid – is an acid that is a compound of hydrogen, oxygen, and a third element, usually a nonmetal. Ex.) HNO3, H3PO4, H2SO4
Naming: Use the root of the third element and add –ic to the end

10. Describing Acids and Bases
Three common theories to describe acids and bases
Arrhenius
Bronsted-Lowry
Lewis

11. 1. Arrhenius Theory A. Arrhenius Acid Hydronium ion (aka H+)
-Increases the [H+] in solution through ionization
HNO3 + H2O  H3O+ + NO3-
Strong Acid – ionizes completely, strong electrolyte
Weak Acid – ionizes partially, weak electrolyte
Hydronium ion (aka H+)

12. Arrhenius Theory, cont. B. Arrhenius Base Hydroxide ion
-Increases the [OH-] in solution through dissociation
NaOH Na+ + OH-
Strong Base – dissociates completely, strong electrolyte
Weak Base – dissociates partially, weak electrolyte
water
Hydroxide ion

13. Which are the following?
HNO3
HBr
H3PO4
NaOH
H2SO4
Ca(OH)2

14. What about ammonia (NH3)?

15. Acid vs. Base
So what makes a solution an acid or a base?

16. 2. Bronsted-Lowry Theory
A. B/L Acid - A species that donates a proton (H+) in a reaction B. B/L Base - A species that accepts a proton (H+) in a reaction

17. Examples… HCl + NH3  NH4+ + Cl- NH3 + H2O  NH4+ + OH-
NH3 GAINS a hydrogen
HCl + NH3  NH4+ + Cl- NH3 + H2O  NH4+ + OH-
B/L Conjugate
Base
B/L Acid
B/L Base
B/L Conjugate
Acid
HCl LOSES a hydrogen
B/L Base
B/L Acid
B/L Conjugate
Acid
B/L Conjugate
Base

18. B/L, cont. Conjugate acid -What remains when a B/L base accepts H+
Conjugate base
-What remains when a B/L acid donates H+

19. Try these
HNO OH-  H2O NO22-
HCl H2O  Cl H3O+

21. More… Amphoteric – species can be both a B/L acid and a B/L base
What is the conjugate base of:
H3O+ ?
H2O ?
HSO4-?
What is the conjugate acid of:
H2O?
NO2-?

22. More…
Monoprotic acid – an acid that can donate only one proton per molecule.
Polyprotic acid – an acid that can donate more than one proton per molecule.

23. 3. Lewis Theory
A. Lewis Acid - Accepts an electron pair B. Lewis Base -Donates an electron pair

24. Summarizing Theories

26. Chapter 15

27. Self ionization of pure water
Hydronium
Hydroxide
[H3O+] = [OH-] =1.0 X 10-7 mol/L
[H3O+] > [OH-] Acid
[H3O+] < [OH-] Base
[H3O+] = [OH-] Neutral

28. How do you find [H3O+] and [OH-]?
Use the ionization constant of water
Remember…
[H3O+] = [OH-] =1.0 X 10-7 mol/L
Therefore…
[H3O+] X [OH-] =1.0 x 10-14M

29. Given: Solution of 1.0 x 10-4 M HNO3
What is the hydronium and hydroxide concentrations?

30. Given: Solution of 1.0 x 10-2 M NaOH
What is the hydronium and hydroxide concentrations?

31. Given: Solution of 1.0 x 10-4 M Ca(OH)2
What is the hydronium and hydroxide concentrations?

32. pH scale
Much simpler to manage
pH scale
0-6 Acid
7 Neutral
8-14 Base

33. Calculating pH
pH = -log[H+]
pOH = -log [OH-]
pH + pOH =14

34. Determine the pH pH 3.0 1.0x10-3 M HCl pH 5.0 1.0x 10-5 M HNO3 pH 4.4
1.0 x 10-4 M NaOH
3.0x 10-2 M KOH
pH 3.0
pH 5.0
pH 4.4
pH 10.0
pH 12.48

35. Indicator
A chemical that changes color to help distinguish acids and bases

36. Neutralization Reaction
Acidic compounds react with basic compounds neutralizing each other
Ex.)
NaOH + HCl  NaCl + H2O
Baking Powder - NaHCO3 & H2C4H4O6
Antacid

37. Titration
A process in which you can determine the concentration of an unknown solution through a neutralization reaction
End point - when an indicator changes color, indicating a change in pH
Equivalence point – when moles of acid equals moles of base

38. Titration set-up Set up system as shown
In buret
Standard solution
Set up system as shown
Add an indicator to flask to show when equivalence point is reached
Add the standard solution until end point is reached
Do calculations
In flask
Known volume
Unknown molarity

39. Titration Calculations
Write balanced chemical reaction
Determine moles of standard solution used to reach equivalence point
Use mole ratio to determine moles of unknown solution neutralized
Find molarity of unknown solution

40. In the titration of 30. 0mL of NaOH, concentration unknown, 45
In the titration of 30.0mL of NaOH, concentration unknown, 45.2 mL of 0.10 M HCl acid was required to neutralize the solution to a phenolphthalein end point. Calculate the molarity of the NaOH.

41. If 32. 0mL of a dilute solution of Ca(OH)2 required 12. 4mL of 0
If 32.0mL of a dilute solution of Ca(OH)2 required 12.4mL of M HCl for neutralization to the end point, calculate the molarity of the Ca(OH)2?

42. Chapter Reviews
Ch. 14
1,2,5,8-10, 13, 17, 22, 26
Ch. 15
1, 3, 6-10, 25-26