1. Acids & Bases
Unit 12

2. Intro to acids & bases Reflect:
What does it mean to ‘ionize’ or ‘dissociate’?

3. Intro to Acids & Bases

4. Intro to Acids & Bases
Do NOT react with metals

5. Intro to Acids & Bases acid base base acid base other (alcohol) base

6. pH Scale salt acid acid alcohol base acid acid & base base acid salt
Reflect:
Classify each of the following as an acid, base, salt, or alcohol.
KCl HCl CH3COOH CH3OH
NaOH H2SO H2O KOH
LiBr HF
salt
acid
acid
alcohol
base
acid
acid & base
base
acid
salt

7. pH Scale
pH Scale: Logarithmic scale that tells you the concentration of H+/H3O+ ions. Every time you move a unit of pH, the [H+] increased/decreases by a power of 10.

8. pH Scale

9. pH Scale & Indicators

10. pH Scale
Indicators: They let you know if a chemical is an acid or a base by a color change. Methyl Orange: From it will be red From it will be yellow

11. pH Scale

12. pH Scale 4.4-8 Sample Problem 1: Which of the following substances
would turn phenolphthalein pink?
CH3OH HCl CH3COOH Ba(OH)2
Sample Problem 2: An unknown substance is found in
a chemistry lab. It turns both methyl orange and
thymol blue a yellow color. What pH range is possible
for this substance?
Alcohol
Acid
Acid
4.4-8

13. pH Scale & Indicators Sample Problem 3: Based on the results of
testing colorless solutions with indicators, which
solution is most acidic?
A solution in which bromothymol blue is blue
A solution in which bromcresol green in blue
A solution in which phenolphthalein is pink
A solution in which methyl orange is red

14. More pH scale & ionization of water

15. More ph scale & ionization of water

16. More pH scale & ionization of water
The pH scale is logarithmic and therefore, moving 1 pH unit changes the concentration by 10x
100x
pH=6
pH=6

17. Key Idea

18. pH Scale
12-base
6-acid
3-acid
13-base
8-base
10-base
2-acid
7-neutral

19. pH Scale

20. More pH scale & Ionization of water

21. More pH scale & ionization of water12 6 3 13 8 10 2 7

23. Salts & Ionization of Water
9 Basic
13 Basic
Buffer: A substance that resists a change in pH

24. Electrolytes

25. Electrolytes H+ Cl- H+ Cl- Cl- H+ H+ H+ H+ Cl- Cl- H+ Cl- H+
Strong Acid Weak Acid H+
Cl- H+
CH3COOH H+
Cl-
Cl- H+
CH3COO-
CH3COOH H+ H+
CH3COOH H+
Cl-
Cl- H+
CH3COOH H+
Cl- H+
CH3COOH
CH3COO-
Strong acids completely ionize
More ions = more electricity
can be conducted.
Weak acids only partially ionize
Only a few ions = only some
electricity can be conducted.

26. Electrolytes

27. HCl – stronger acid – more likely to dissociate – more ions
Electrolytes
Acid
Salt
Alcohol
Base
Acid
Base
Salt
Alcohol
HCl – stronger acid – more likely to dissociate – more ions

28. Titration Reflect: What does it mean to neutralize something?
What is Molarity?

29. Titration

30. Titration Chemists perform acid/base neutralization reactions called
Titrations.
A Titration:
Is an experiment that uses a
buret to mix solutions together in very accurate amounts.
A way to find out the
concentration (Molarity) of an acid or a base.

31. Titration
3. Uses a Standard Solution – an acid or base whose concentration is accurately known 4. Uses an End Point, signified by a color change in your indicator, as a way to tell you have created a neutral solution [acid ions] = [basic ions]

32. Titration
If we want a neutral endpoint using Bromothymol Blue, we would want to titrate until we got a green color.

33. Titration: Reading a Buret

34. Titration
The formula you should use when you see the words titration or neutralize is:

35. Titration

36. Titration

37. Titration

38. Titration
MAVA = MBVB (0.100 M)(32 mL) = (0.35 M)VB VB = 9.14 mL (MA)(25 mL) = (0.40 M)(40 mL) MA = 0.64 M

39. MAVA = MBVB (0.100 M)(5.14 mL) = MB(10.61 mL) MB = 0.048 M
Titration
MAVA = MBVB (0.100 M)(5.14 mL) = MB(10.61 mL) MB = M

40. [H2SO4] = 0.15 M MAVA = MBVB 2(0.15 M)(20 mL) = MB(50 mL) MB = 0.12 M
Titration
[H2SO4] = 0.15 M MAVA = MBVB 2(0.15 M)(20 mL) = MB(50 mL) MB = 0.12 M

41. MAVA = MBVB (0.2 M)(15.6 mL) = 2MB(4.0 mL) MB = 0.39 M
Titration
MAVA = MBVB (0.2 M)(15.6 mL) = 2MB(4.0 mL) MB = 0.39 M

42. Titration
Problem 6: If 30.0 mL of carbonic acid is used to neutralize 1.5 M NH3, what volume of base will be neutralized by the acid, if the carbonic acid has a concentration of 1.0 M?
MAVA = MBVB
(2M)(30 mL) = (1.5M)(VB)
VB = 40 M

43. Conjugate Acid-Base Pairs
Reflect:
What is the Arrhenius definition of:
ACIDS BASES

44. Conjugate Acid-Base Pairs
Arrhenius Acid/Base theory has some shortcomings:
Limits acid/base reactions to aqueous solutions
Does not explain why acids ionize
Does not include bases without OH- ions (ex: NH3)

45. Conjugate Acid-Base Pairs
Bronsted-Lowry (aka conjugate acid/base pairs):
Bronsted- Lowry acids are proton (H+ ) donors
Bronsted – Lowry bases are proton (H+ ) acceptors
For example:
H2CO3 + H2O  H3O+ + HCO3-

46. Conjugate Acid- Base Pairs
Conjugate acid-base pairs : Are similar compounds that differ by the presence of one proton, or H+.

47. Conjugate Acid-Base Pairs
Are similar compounds that differ by the presence of one proton (H+)
Base
Acid
Conj. Acid
Conj. Base
Acid
Base
Conj. Base
Conj. Acid

48. Conjugate Acid – Base Pairs
Amphoteric: A substance that can act as either an acid or a base. (ex. H2O)

49. Conjugate Acid Base Pairs
Practice Multiple Choice
Ques. #1-12 2 1 4 3