1. CH. 16 ACID -- BASE 16.4 pH scale (pOH) 16.1 Definition 16.2
Bronstad-Lowry
Conjugate Pairs
Strength
Leveling Effect
16.3
Dissociation of water Kw
16.5
Strong Acid
Strong Base
pH & [ ]
16.6
Weak Acids
Ka & pH
% Ionization
Polyprotic Acids
16.7
Weak Bases
Kb & pH
Acid Base Yields
16.9
Salt Solutions
Anions/Cations
Lewis
16.8
Ka & Kb Relation
16.10
Binary Acids
Oxyacids
Carboxylic Acids
16.11
Bronstad-Lowry

2. ACID BASE CHEMISTRY TERMS, ETC. AMPHOTERIC:
Subst. acts as either an acid or a base
Proton (Acidic p+):
H+ ion; the acidic hydrogen(s) present in an acid
HNO3: one H+
H2SO4: two H+
H3PO4: three H+
MONOPROTIC ACID:
An acid w/ one H+
DIPROTIC ACID:
An acid w/ two H+
POLYPROTIC ACID:
An acid w/ 3 or more H+

3. TERMS, ETC.
ACID:
Subst. in H2O incr [H+]
BASE:
Subst. in H2O incr [OH-]
Effects H+ Ion in H2O
HYDRONIUM ION:
H2O (l) + H+1 (aq) > H3O+1 (aq)

4. BRONSTAD-LOWRY
ACID:
Subst. that donate acidic proton, H+
Proton donor
HCl(g) + H2O(l) ----> H3O+(aq) + Cl-(aq)
BASE:
Subst. that gains acidic proton, H+
Proton acceptor

5. Figure UN
Title:
Brønsted–Lowry acids and bases.
Caption:
Because the emphasis in the Brønsted–Lowry concept is on proton transfer, the concept also applies to reactions that do not occur in aqueous solution. In the reaction between HCl and NH3, for example, a proton is transferred from the acid HCl to the base NH3.
Notes:
Keywords:

6. CONJUGATE ACID-BASE PAIRS
Acid, loses H+, form conjugate base
Base, gains H+, forms conjugate acid
acid1
base2
base1
acid2
CONJUGATE ACID-BASE PAIRS

7. Fig 16.3
pg. 657
Figure 16-04
Title:
Relative strengths of some conjugate acid–base pairs.
Caption:
The two members of each pair are listed opposite each other in the two columns. The acids decrease in strength from top to bottom, whereas their conjugate bases increase in strength from top to bottom.
Notes:
Keywords:

8. RELATIVE STRENGTH
HX(aq) + H2O(l) ----> H3O+(aq) + X-(aq)
H2O stronger base than X X weaker base --- equilib
+ acid ion of weak acid react w/ H2O, produces H3O+
Strong Acid + Weak Base --- Acidic
HCl(g) + H2O(l) ----> H3O+(aq) + Cl-(aq)
H2O stronger base than Cl-

9. X- stronger base than H2O
X stronger base <---- equilib
Weak Acid + Strong Base --- Basic
CH3COOH(aq) + H2O(l) ----> H3O+(aq) + CH3COO-(aq)
CH3COO- stronger base than H2O
Proton Transfer: ability of 2 bases attract protons

10. AUTOIONIZATION OF WATER
Kc[H2O]2 = Kw = [H3O+][OH-] = 1.0*10-14
Solution
Acid [H3O+] > [OH-]
Neutral [H3O+] = [OH-]
Basic [OH-] > [H3O+]

11. Kw: constant for water, 1*10-14 Kw = [H+][OH-] 1*10-14 = [H+][OH-]
pH SCALE
NEUTRAL
( )
MILD
ACIDIC
MILD
BASIC 7 14
WEAK
ACIDIC
WEAK
BASIC
STRONG
ACIDIC
STRONG
BASIC
Kw: constant for water, 1*10-14
Kw = [H+][OH-]
1*10-14 = [H+][OH-]
pKw = -Log [H2O]
= -Log [1*10-14]
= -Log [10-14] -Log [1]
= -(-14) - 0 = 14
pKw = pH + pOH
pH = -Log [H+]
pOH = -Log [OH-]
[H+] = 1*10-pH
[OH-] = 1*10-pOH
Log 10exp = exp
log 106 = Log 10-4 = -4
Log 1 = 0

12. Fig. 16.5
pg 663
Figure 16-05
Title:
H+ concentrations and pH values of some common substances at 25 oC.
Caption:
The pH of a solution can be estimated using the benchmark concentrations of H+ and OH– corresponding to whole-number pH values.
Notes:
Keywords:

13. pH -- pOH -- [H+] -- [OH-]
CALCULATIONS
Formulas to Use
Constants
Kw = 1 *10 –14
pKw = 14
pH = -log [H+]
pOH = -log [OH-]
Rules for LOGS
[H+] = 1*10-pH
Log 1 = 0
[OH-] = 1*10-pOH
Log 10exp = exponent

14. Rules for LOGS
Log 1 = 0
Log = 3.17
Log 10exp = exponent

15. Calculate pH for the
following solutions
1) [H+] = 1 * 10-9
pH = -log (1*10-9) = -(-9) = 9
2) [H+] = 0.001
0.001 = 1*10-3
pH = -log (1*10-3) = -(-3) = 3

16. Find pH & pOH 3) [H+] = 3.6 * 10-2 pH = -log(3.6*10-2) = 1.44
= 2 – 0.56
= 1.44
-log 10-2 = 2 OR
pKw = pH + pOH
14 = pOH
pOH = 14 – 1.44
= 12.56
pOH OR
= 2.78*10-13
pOH = 13 – log 2.78
= 13 – 0.44 =

17. If [H+] is 6.7*10-9 mol/L, what is the pH? ACIDIC, BASIC, NEUTRAL
What is the [OH-]? What is the pOH?
Find pH
Find pOH
pH = -log(6.7*10-9)
= 9 – log 6.7
= 9 – 0.83
= 8.17
pOH = 14 – 8.17
= 5.83
Find [OH-]
BASIC
[OH-] = 1* OR
[OH-] =
1*10-14
6.7*10-9
= 1.49*10-6

18. TITRATIONS
Strong Acid + Strong Base  Neutral
+/- ions of acid not react w/ H2O
Strong Acid + Weak Base --- Acidic
+ acid ion weak acid react w/ H2O, produces H3O+
HBr + NH4OH NH4 is a weak acid reacts w/ H2O to produce H3O+
Weak Acid + Strong Base --- Basic
acid ion weak base produces OH-
HCN: CN- is weak base reacts w/ H2O to produce OH-
Weak Acid + Weak Base ---- ???????
Both +/- ions react w/ H2O

19. DISSOCIATION
HA: acid A-: anion Ka: acid-dissociation constant
Strong Acid -- SA
HA(aq) + H2O(l) > H3O+(aq) + A-(aq)
SA in solution; no HA present,
most all H3O+
@ equilibrium Qc = Kc >>>> 1
Weak Acid -- WA
HCN(aq) + H2O(l) > H3O+(aq) + CN-(aq)
WA in solution; no H3O+ present,
most all HA
@ equilibrium Qc = Kc <<<< 1
Stronger Acid ==> higher [H3O+] ===> larger Ka
Smaller Ka ==> less % dissed ====> weaker acid

20. STRENGTH
Strong Acid/Base
ionize completely
equilibrium lies far to the right
HCl > H+ + Cl-
NaOH -----> Na+ + OH-
Weak Acid
slightly ionize
equilibrium lies far to the left
HC2H3O2 + H2O <-----> H+ + C2H3O2-
IONIZATION CONSTANTS
Ka: acid dissociation constant
Kb: base dissociation constant

21. Ka Values MONOPROTIC ACIDS
Increasing acid strength
Acid Ka
Chlorous HClO4
Nitrous HNO2
Hydrofluoric HF
Formic HCOOH
Acetic CH3COOH
Propanoic CH3CH2COOH
Hypochlorous HClO
Hydrocyanic HCN
1.1*10-2
7.1*10-4
6.8*10-4
1.8*10-4
1.8*10-5
1.3*10-5
2.9*10-8
6.2*10-10

22. Problem Solving A-B Equilibria
Steps
1. Write eqn & Ka/b expression
2. I.C.E. table
3. Define “x” as ; HA
4. Assume “x” very small
5. 5% rule
2 Assumptions
1. [H3O+] from water ignore
2. WA diss little, no  in concen
Ka * Kb = Kw

23. Ka = 6.8*10-4 for 0.75 M hydrofluoric acid solution is.
Determine the concentrations of H3O+, A-, & OH-.
Also, find the pH, pOH, & % acid dissociation.
1st write eqn & Ka
2nd construct table
3rd determine “change, x”
[H3O+] = [F-]
Kw = [H3O+] [OH-]
4th assume x negligible; x => 0.75

24. pH = -Log(0.0223) = 1.65
pOH = = 12.35 OR
= -Log(4.4*10-13) = 12.36
% Diss = /0.75 * 100 = 3.0 %

25. HA % Dissociation The initial concen of an acid is 3.2*10-2
then at equilibrium the concen is now 6.4*10-5
What is the % diss?
HA% = [HA]diss/[HA]init * 100
HA% = [2.8*10-4]/[1.2*10-2] * 100 = 2.3 %

26. Classify Acid - Base Strengths WA Halogen acid: HF H not bonded to O:
HCN, H2S, H3P
Oxo acids: when # O’s < 2 H+
HNO2, HClO2, H3PO3
Carboxylic Acids:
- COOH SA
Halogen acids:
HCl, HBr, HI
Oxo acids: when # O’s > 1 H+
HNO3, HClO4, H2SO4 SB
Contain O-2 or OH-
Group 1A active metals: MOH, M2O
Li, Na, K, Rb, Cs
Group 2A active metals: M(OH)2, MO
Ca, Sr, Ba WB
Cmpds w/ e--rich N atom
NH3, amines

27. Ka acetic acid = 1.8*10-5
Ka nitrous acid = 4.4*10-4
nitrous acid more ionized in soln
BASE
NH3 + H2O <---> NH4+ +OH-
Kb ammonia = 1.8*10-5

28. S.A. yields weak conjugate base
W.A. yields strong conj. base
MONOPROTIC ACIDS
Ka Acid
Kb Conj. Base
Increasing acid strength
Increasing base strength
8.3* SO4-2
8.3* ClO2-
1.4* F-
5.56* C2H3O2-
2.9* OCl-
1.8* NH3
1.2* HSO4-
1.2* HClO2
7.2* HF
1.8*10-5 HC2H3O2
3.5* HOCl
5.6* NH4+

29. acid strength
conj. base
strength
HCl Strong Cl-
H2SO HSO4-
HNO NO3-
H3O H2O
HSO Weak SO4-2
H2SO HSO3-
H2PO H2PO4-
HF F-
CH3COOH CH3COO-
H2CO HCO3-
H2S HS-
HSO SO3-2
H2PO HPO Weak
HCN CN-
NH NH3
HCO CO3-2
HPO PO4-3
H2O OH Strong

30. RXN DIRECTION
Direction of SA & SB to form WA & WB
H2PO NH3 <------> NH4+ + HPO4-2
H2PO4- SA than NH4+
HS- + H2O <------>
H2S + OH-
H2S SA than H2O
Acid Base rxn goes dir: if HA reacts w/ base lower on list

31. Diprotic & Triprotic Acids
H2CO3: 2 acidic protons
Ka values for each H+
Ka1 = 4.3*10-7
Ka2 = 5.6*10-11
typically weak polyprotic acid
Ka1 > Ka2 > Ka3
means????
-each step of dissociation is successively weaker
-loss of 2nd & 3rd proton occurs less readily
Why????
should not be surprising
think in terms of charges, +/- being attracted

32. Various Ways to Describe Acid Strength
Property S.A W.A.
Ka value
Ka is large
Ka is small
Position of dissociation
equilibrium
Far to right
Far to left
Equilibrium [H+]
compared to [HA]o
[H+] [HA]o
[H+]<<[HA]o
Strength of conj.base
compared to H2O
A- much weaker
base than H2O
A- much stronger
base than H2O

33. Acid Strength Nonmetal Hydrides
The stronger the acid the better it is at donating H+
2 factors of Acid Strength
-- depends how easily the H+ is lost
1) Bond Polarity
More polarized bond, quicker H+ lost, greater acid strength
2) Bond Strength
Larger “none H” atom is, weaker the bond, greater acid strength
Metal Ion Acid Strength
high charge density, small metal ions: Fe+3, Al+3, Cu+2, Pb+2, Zn+2, Ni+2

34. PROPERTIES OF SALTS
pH of salt soln: A-B properties
of cation & anion
1. SA + SB ----> Neutral
2. SA + WB ----> Acidic
3. WA + SB ---> Basic
1. Cat- & An-ions not react w/ water to form H3O+ or OH-
2. Anion inert;
Cation WA, form H3O+
3. Cation inert;
Anion WB, form OH-

35. 4. WA + WB ----> ????
Both ions undergo proton transfer
Ka cation > Kb anion: ACIDIC
Kb anion > Ka cation: BASIC
Ka cation = Kb anion: NEUTRAL

36. Leveling Effect Lewis Acids - Bases
All Bronstad acids form H3O+ in water & bases OH-
SA completely form H3O+
SB completely form OH-
Lewis Acids - Bases
Molecules w/ central atom < 8 val e-
Polar molecules w/ dbl bond
Metal ions dissolved in water
ID Lewis A & B
Cl- + BCl3 <----> BCl4-
Cl- form coval bond to B; Cl- 4 e- pair
BCl3 accepts e- pair, ACID