Title: Diapositive 1
1Chemistry B11
Chapter 9 Acids and Bases
2Acids and Bases
Acids sour
Bases bitter or salty
3Acids and Bases
Arrhenius definition
Acid produces H3O
CH3COOH(aq) H2O(l) CH3COO-(aq)
H3O(aq)
H3O (Hydronium ion)
H(aq) H2O(l) H3O(aq)
Base produces OH-
H2O
NaOH(s) Na(aq) OH-(aq)
NH3(aq) H2O(l) NH4(aq) OH-(aq)
4Acids and Bases
Bronsted and Lowry definition
Acid donates H (proton)
Base accepts H (proton)
5Acids and Bases
HCl H2O Cl- H3O
acid
base
Conjugate base
Conjugate acid
Conjugate acid-base pair
Conjugate acid-base pair
C6H5OH H2O C6H5O- H3O
acid
base
Conjugate base
Conjugate acid
Conjugate acid-base pair
Conjugate acid-base pair
6Acids and Bases
Weak acid and base is partially ionized in
aqueous solution.
produces less H and OH-
CH3COOH(aq) H2O(l) CH3COO-(aq) H3O(aq)
NH3(aq) H2O(l) NH4(aq) OH-(aq)
Strong acid and base is completely ionized in
aqueous solution.
produces more H and OH-
HCl(aq) H2O(l) Cl-(aq) H3O(aq)
NaOH(aq) H2O(l) Na(aq) OH-(aq)
7Acids and Bases
Monoprotic acids HCl
Diprotic acids H2SO4
Triprotic acids H3PO4
8Naming binary acids
HF
F- flouride ion Hydroflouric acid
HCl
Cl- chloride ion Hydrochloric acid
H2S
S2- sulfuride ion Hydrosulfuric acid
9Naming ternary acids
-ite ion
-ous acid
Anion
-ate ion
-ic acid
HNO2
NO2- Nitrite ion Nitrous acid
HNO3
NO3- Nitrate ion Nitric acid
H2CO3
CO32- carbonate ion carbonic acid
H2SO3
SO32- sulfurite ion sulfurous acid
10Ionization constant
HA H2O A- H3O
A- H3O
K
not for strong acids
Equilibrium constant
HA H2O
- Log Ka pKa
11pH and pOH
H2O H2O OH- H3O
KW H3O OH- (110-7) (110-7)
H3O OH- 110-14
pH pOH 14
12pH and pOH
pH - log H3O or -log H
pOH - log OH-
pH scale
0
7
14
Base
Neutral
Acid
H3O ?
H3O ? and OH- ?
13pH meter and pH indicators
14Acid Reactions
1. Reaction with metals (strong acids) produces
H2 and a salt.
Mg(s) 2HCl(aq) MgCl2(aq) H2(g)
15Acid Reactions
3. Neutralization between an acid and a
base. produces a salt and water
KOH(aq) 2HCl(aq) KCl(aq) H2O(l)
2NaOH(aq) H2SO4(aq) Na2SO4(aq) 2H2O(l)
Strong acids react with strong bases. Weak acids
react with weak bases.
16Titration (Neutralization reaction)
MB known VB known
MA unknown VA known
Equivalence point equal amount of acid (H)
and base (OH-) (pH 7).
2NaOH 1H2SO4 ? 2NaSO4 2H2O
17Buffers
acid or base
pH stays constant
Buffer
Equal molar amount of a weak acid and a salt of
weak acid. Equal molar amount of a weak acid and
its conjugate base.
1 mole CH3COOH 1 mole CH3COONa 1 mole CH3COOH
1 mole CH3COO-
18Buffers
pH of blood 7.4
Carbonate buffer H2CO3 / HCO3-
Phosphate buffer H2PO4- / HPO42-
Proteins buffer
H2CO3 OH- ? HCO3- H2O HCO3- H3O ? H2CO3
H2O
19Buffers
If AH (weak acid) A- (conjugate base)
pH of buffer pKa of weak acid