I. Nature of Acids and Bases
A. Historical
1. Sour Taste
Chapter 10 - Acid and Bases
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2. React with metals
to yield H2
3. Changes the color of certain Organic
Compounds (Indicators)
4. React with oxides and hydroxides of Metals
Acid + Base
Salt + Water
HCl + NaOH
NaCl + H2O
Neutralization
Chapter 10 - Acid and Bases
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1
B. Arrhenius Concept - ~ 1884
1. Acids
Any substance when dissolved in
water, increases the [H+].
2. Bases
Any substance when dissolved in
water, increases the [OH-].
3. Neutralization
The reaction of an acid with a base
producing a salt and water.
HBr + KOH
KBr + H2O
H+ + OH-
H2 O
Chapter 10 - Acid and Bases
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C. Bronsted Concept ~ 1923
1. Acids
Any substance that donates the proton.
2. Base
Any substance that accepts the proton.
H O
H
F
F
H
H
H
F
H
H N H
H N
H
H O
H O H
H F
H
H O H
H O
H O
H
H
H
Bronsted
Bronsted
Conjugate
Conjugate
Base
Acid
Base
Acid
Conjugate Acid - Base Pair
Conjugate Base - Acid Pair
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2
H
HN
H
97 %
H
HNH
H
3%
H O H
Aqueous Ammonia
H O
Ammonium Hydroxide
D. Lewis Concept
H O H
H+
O H
H
HNH
H
H O
H
HN
H
H O H
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1. Acids
The species that can form a covalent bond
by ACCEPTING an electron pair.
2. Base
The species that can form a covalent bond
by DONATING an electron pair.
H3B
H3B NH3
+ :NH3
HH
H
NH
B
H
H HB NHH
H
H
H
AlCl3 +3 Cl
AlCl6-3
3-
Cl
Cl
Cl
Cl
Al Cl
Cl
Al
Cl Cl
Cl
Chapter 10 - Acid and Bases
Chapter 10 Acid & Bases
Cl
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3
II. Behavior of Acids and Bases
A. Auto-ionization
H O
H O
H
H
H O H
H2 O
H O
H
H+ + OH-
B. Amphoterism
The ability of a substances to act as
either an acid or a base.
Chapter 10 - Acid and Bases
Al(OH)3 + HCl
Base
AlCl3 + H2O
Acid
Chapter 10 - Acid and Bases
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8
4
Al(OH)3 + HCl
Base
AlCl3 + H2O
Acid
Chapter 10 - Acid and Bases
Al(OH)3 + HCl
Base
9
AlCl3 + H2O
Acid
1+
Al(OH)3(H2O)3(aq) + H3O+
Base
Acid
Al (OH)2(H20)4 (aq) + H2O(aq)
Chapter 10 - Acid and Bases
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Al(OH)3 + NaOH
Acid
NaAlO2 + H2O
Base
Chapter 10 - Acid and Bases
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In the following reaction which is the
acid and which is the Base?
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C. Strength of Acids
1. Leveling Effect
The situation that all acids stronger than the
conjugate acid of the solvent will be have the
same acidity as the solvents conjugate acid.
WATER as solvent
H3O+ + A
H-A
+ H2O
H-Cl
+ H2O
H3O+ + Cl
H-CN + H2O
H3O+ + CN
Chapter 10 - Acid and Bases
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Strong Acid: An acid that is completely
dissociated in water.
HCl
HBr HI
HClO4
H2SO4
HClO3
Chapter 10 - Acid and Bases
Chapter 10 Acid & Bases
HNO3
14
7
Strong Acid: An acid that is completely
dissociated in water.
HCl
HBr HI
HClO4
H2SO4
HClO3
HNO3
2. Predicting Relative Acid Strength for
Binary Acids (H-X)
S
t
r
o
n
g
e
r
Stronger
Periodic Table
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3. Predicting Relative Acid Strength for
Ternary Acids (H-O-X)
a. Metal vs Nonmetal
HClO
NaOH
Cl O H
Na O H
WHY HERE?
Inductive Effectn
The attraction of electrons from adjacent
bond by more electronegative atoms.
b. Number of Nonhydroxyl Oxygens
O N O H
O N O H
O
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c. Within a Family, go for High EN
H2SO3 > H2SeO3
D. Predicting the Products for Acid - Base
Reactions
1. Strong acid - Strong Base
HClO3 + LiOH
LiClO3 + H2O
2. Weak acid - Strong Base
HCN + KOH
KCN + H2O
3. Strong acid - Weak Base
H2SO4 + NH3
(NH4)2SO4
4. Weak Acid - Weak Base
HNO2 + NH3
NH4NO2
Chapter 10 - Acid and Bases
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D. Writing Chemical Equations for Acid Base Reactions
1. Strong acid - Strong Base
HClO3 + LiOH
LiClO3 + H2O
a. Total Ionic Equation
H++ClO3- + Li++OHH
Li+ + ClO3- + H2O
b. Net Ionic Equation
OHH2 O
+
2. Weak acid - Strong Base
HCN + KOH
KCN + H2O
a. Total Ionic Equation
HCN + K+ + OH-
HCN
K+ + CN- + HOH
b. Net Ionic Equation
+ OHCN- + HOH
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3. Strong acid - Weak Base
H2SO4 + 2 NH3
(NH4)2SO4
a. Total Ionic Equation
2H+ + SO42- + 2 NH3
2 NH4+ + SO42-
b. Net Ionic Equation
2H+ +
2 NH3
2 NH4+
4. Weak Acid - Weak Base
HNO2 + NH3
NH4NO2
a. Total Ionic Equation
HNO2 + NH3
NH4+ + NO2-
b. Net Ionic Equation
HNO2 + NH3
NH4+ + NO2-
Chapter 10 - Acid and Bases
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