1. To learn about two models of acids and bases
Objectives
To learn about two models of acids and bases
To understand the relationship of conjugate acid-base pairs
To understand the concept of acid strength
To understand the relationship between acid strength and the strength of the conjugate base
To learn about the ionization of water

2. HCl, HF, HBr :HydroChloric,Fluoric..acid
A. Acids and Bases
The Arrhenius Model
Acid – produces hydrogen ions H+ in aqueous solution: H2SO4 Sulfuric Acid HNO3 Nitric Acid
HCl, HF, HBr :HydroChloric,Fluoric..acid
Base – produces hydroxide ions OH- in aqueous solution NaOH Sodium Hydroxide KOH Potassium Hydroxide Mg(OH)2

3. The Bronsted-Lowry Model
A. Acids and Bases
The Bronsted-Lowry Model
(1923 Danish/English independent submittals)
Acid – proton donor (gives H+ )
Base – proton acceptor (takes H+)
The general reaction for an acid dissolving in water is

4. The Bronsted-Lowry Model
A. Acids and Bases
The Bronsted-Lowry Model
Acid-base conjugate pairs consist of an acid that donates the H+ and the ion it becomes.

5. The Bronsted-Lowry Model
A. Acids and Bases
The Bronsted-Lowry Model
Water acts as a base accepting a proton from the acid. (B-L Base)
hydronium ion (H3O+) (Conjugate Acid)

6. The Arrhenius Model is limited to Aqueous
A. Acids and Bases
The Arrhenius Model is limited to Aqueous
The Bronsted-Lowry Model can also relate to non-aqueous reactions:
NH3 + HCl  NH4+ + Cl-
CH3COOH + H2O  CH3COO- + H3O +

7. A. Acids and Bases
Identify the Bronsted-Lowry acid/base conjugate pairs in the following reactions:
HSO4- + OH-  SO4-2 + H2O
SO3-2 + H2O  HSO3- + OH-
NH3 + HNO3  NH4+ + NO3-

8. The general acid/base pattern is: Acid + Base  salt + water
A. Acids and Bases
The general acid/base pattern is:
Acid + Base  salt + water
H__ + __OH  ____ + H2O
HCl + NaOH  NaCl + H2O
ID the Arrhenius Acid/Base and B-L Pairs…

9. Strong acid – completely ionized or completely dissociated
B. Acid Strength
Strong acid – completely ionized or completely dissociated

10. Weak acid – low ionization of acids
B. Acid Strength
Weak acid – low ionization of acids

11. A strong acid contains a relatively weak conjugate base.
B. Acid Strength
A strong acid contains a relatively weak conjugate base.
HCl + H2O  H3O+ + Cl-
Whereas the acid will quickly donate a proton (strong acid), the conjugate base will not quickly accept a proton (weak).

12. Common strong acids are
B. Acid Strength
Common strong acids are
Sulfuric acid, H2SO4
Hydrochloric acid, HCl
Nitric acid, HNO3
Are weak acids the same as dilute strong acids?

13. Typically a weak acid (COOH)
B. Acid Strength
Oxyacid – acidic proton is attached to an oxygen atom
Organic acid – have a carbon atom backbone and commonly contain the carboxyl group
Typically a weak acid (COOH)

14. B. Acid Strength

15. C. Water as an Acid and a Base
Water is amphoteric (amphiprotic) – it can behave as either an acid or as a base
Amphiprotic - etymology…
ambi-Ringo Starr
ringo_starr.images6.com/ringo_starr.html

17. C. Water as an Acid and a Base (Amphiprotic)
Ionization of water - ID the B-L conjugate pairs
Concentration of hydronium and hydroxide are equal in pure water

18. C. Water as an Acid and a Base
Product of [H3O+] and [OH] is always constant in all solutions.
Water is equally both an acid and a base

19. C. Water as an Acid and a Base
pH range
0.? – 7
7 – 14 7

20. To learn about two models of acids and bases
Objectives Review
To learn about two models of acids and bases
To understand the relationship of conjugate acid-base pairs
To understand the concept of acid strength
To understand the relationship between acid strength and the strength of the conjugate base
To learn about the ionization of water
Work Session: Section Review Page 572 1, 3, 4, 5, 6

21. To understand pH and pOH
Objectives
To understand pH and pOH
To learn to find pH and pOH for various solutions
To use a calculator to find pH and [H+]
To learn methods for measuring pH of a solution
To learn to calculate the pH of strong acids   

22. The “p scale” is used to express small numbers. pH = log [H+]
A. The pH Scale
The “p scale” is used to express small numbers.
pH = log [H+]
What is the pH if [H+] = 1 X 10 -7? Calculator practice- do the log function?
If [H+] = 2.3 X 10-5?
pH = 4.64 is this acid or base?

23. A. The pH Scale
Because the pH scale is a log scale based on 10, the pH changes by 1 for every power of 10 change in the [H+].

24. Calculate the pH given the following concentrations: [H+] = 1.0 X 10-5
A. The pH Scale
Calculate the pH given the following concentrations:
[H+] = 1.0 X 10-5
[H+] = 1.0 X 10-11
[H+] = 3.4 X 10-4
[H+] = 2.6 X 10-8
[H+] = 2.3 X 10-5
[H+] = 1.9 X 10-6

25. Calculate the pOH if [OH] = 1.0 X 10-6 pOH = 6
A. The pH Scale
pOH scale
pOH = log [OH]
Calculate the pOH if [OH] = 1.0 X 10-6
pOH = 6
remember [H+] [OH] = 1.0 X 10-14
If [OH] = 1.0 X 10-6 , then [H+] = 1.0 X 10-8
If [OH] = 6 , then [H+] = 8
Since pH + pOH = 14.00
pOH = – pH (shortcut)

26. Knowing the pH, determine the pOH: [H+] = 1.0 X 10-5 pH = 5, pOH = 9
A. The pH Scale
Knowing the pH, determine the pOH:
[H+] = 1.0 X pH = 5, pOH = 9
[H+] = 1.0 X pH = 11, pOH = 3
[H+] = 3.4 X pH = 3.47, pOH = ?
[H+] = 2.6 X pH = 7.59, pOH = ?
[H+] = 2.3 X pH = 4.64, pOH = ?
[H+] = 1.9 X pH = 5.72, pOH = ?

27. Can you determine the [H+] from pH? If pH = 3.98, what is the [H+] ?
A. The pH Scale
Can you determine the [H+] from pH?
If pH = 3.98, what is the [H+] ?
Inverse log function…..
[H+] = inverse log (-pH)
[H+] = inverse log (- 3.98)
[H+] = 1.05 X 10-4

28. Calculate the [H+] given the following pH: pH = 5 [H+] = ?
A. The pH Scale
Calculate the [H+] given the following pH:
pH = 5 [H+] = ?
pH = 7 [H+] = ?
pH = [H+] = ?
pH = [H+] = ?
pH = [H+] = ?
pH = [H+] = ?

29. In an acid solution the indicator will be in the HIn form.
B. Measuring pH
Indicators – substances that exhibit different colors in acidic and basic solutions
In an acid solution the indicator will be in the HIn form.
In a basic solution the indicator will be in the In form.

30. Phenolphthalein color change 8.0 – 9.8
B. Measuring pH
Phenolphthalein color change 8.0 – 9.8
                                                                                                                                                                                    
                                                                                                                                                                                       

31. Bromothymol Blue color change 6.0 – 7.6
B. Measuring pH
Bromothymol Blue color change 6.0 – 7.6
                                                                                                                                                                                    
                                                                                                                                                                                       

32. Thymol Blue – tri color! B. Measuring pH
                                                 
                                                                                                                                                                                    

33. B. Measuring pH
Other methods
Indicator paper
pH meter
Cabbage juice

34. To understand pH and pOH
Objectives Review
To understand pH and pOH
To learn to find pH and pOH for various solutions
To use a calculator to find pH and [H+]
To learn methods for measuring pH of a solution
To learn to calculate the pH of strong acids   
Work Session: Review Page 581 1, 2, 3, 4

35. To learn about acid-base titrations
Objectives
To learn about acid-base titrations
To demonstrate calculations and techniques for titration lab
To understand the general characteristics of buffered solutions

37. A. Acid-Base Titrations
Titration – delivering a measured volume of a solution of known concentration into the solution being analyzed
Titrant – a standard solution
Buret – device used for accurate measurement of the delivery of a liquid
Stoichiometric point (equivalence point) – when just enough titrant has been added to react with all of the solution being analyzed

38. A. Acid-Base Titrations
Titration curve (pH curve) – plot of the data (pH vs volume) for a titration

39. A. Acid-Base Titrations
HCl + NaOH  NaCl + H2O
Stoichiometrically, there is a 1 to 1 ratio of H+ to OH- ions between HCl and NaOH
For this reason, we can use the dilution equation in the form MacidVacid = MbaseVbase to determine the amount of one Molarity solution to completely neutralize a given amount of another Molarity solution

40. A. Acid-Base Titrations
HCl + NaOH  NaCl + H2O
What volume of 1 M HCl would be required to completely neutralize 20 ml of 2 M NaOH?
MacidVacid = MbaseVbase
Macid =
Vacid =
Mbase=
Vbase=

41. A. Acid-Base Titrations
HCl + NaOH  NaCl + H2O
What volume of 1 M HCl would be required to completely neutralize 20 ml of 2 M NaOH?
MacidVacid = MbaseVbase
Macid = 1 M
Vacid = ?
Mbase= 2M
Vbase= 20 ml

42. A. Acid-Base Titrations
HCl + NaOH  NaCl + H2O
What volume of 1 M HCl would be required to completely neutralize 20 ml of 2 M NaOH?
MacidVacid = MbaseVbase
Vacid = MbaseVbase
Macid
Vacid = (2M)(20 ml) = 40 ml
(1 M)

43. A. Acid-Base Titrations
HCl + KOH  KCl + H2O
Calculate the volume of 0.30 M HCl needed to titrate 75.0 ml of M KOH. MacidVacid = MbaseVbase
Macid =
Vacid =
Mbase=
Vbase=

44. A. Acid-Base Titrations
HCl + KOH  KCl + H2O
Calculate the volume of 0.30 M HCl needed to titrate 75.0 ml of M KOH. MacidVacid = MbaseVbase
Macid = 0.30 M
Vacid = ?
Mbase= M
Vbase= 75.0 ml

45. A. Acid-Base Titrations
HCl + KOH  KCl + H2O
Calculate the volume of 0.30 M HCl needed to titrate 75.0 ml of M KOH. MacidVacid = MbaseVbase
Vacid = MbaseVbase
Macid
Vacid = (0.150M)(75 ml) = ml HCl
(0.30 M)

46. A. Acid-Base Titrations (Lab Prep)
HCl + NaOH  NaCl + H2O
Using (MacidVacid = MbaseVbase), calculate the volume of 1.0 M HCl required to titrate 20.0 ml of 0.5 M, 1.0 M, and 2.0 M NaOH to the equivalence point. Show the calculations and record the HCl volumes in Table 1.

47. Presence of a weak acid and its conjugate base buffers the solution
B. Buffered Solutions
Buffered solution – resists a change in its pH when either an acid or a base has been added
Presence of a weak acid and its conjugate base buffers the solution

48. B. Buffered Solutions

49. C. Lab Techniques
Buret Filling
Buret Clearing
Buret Reading
Carol

50. To learn about acid-base titrations
Objectives Review
To learn about acid-base titrations
To demonstrate calculations and techniques for titration lab
To understand the general characteristics of buffered solutions
Work Session: Review Page 586 1, 3, 4

51. A. The pH Scale

52. A. The pH Scale

53. C. Calculating the pH of Strong Acid Solutions
Determine the [H+].
pH = log[H+]