1. Ch. 15/16: Acids and Bases Definitions of Acids and Bases
Conjugate Acids and Bases
Amphoteric Substances

2. Definitions of Acids and Bases
Arrhenius
Most specific/exclusive definition
Created by Svante Arrhenius, Swedish
Acid : compound that creates H+ in an aqueous solution
Base : compound that creates OH- in an aqueous solution
HNO3  H+ + NO3-
NaOH  Na+ + OH-

3. Definitions of Acids and Bases
Bronsted-Lowry
A bit more general and more common
Created by two scientists around the same time (1923)
Acid: Molecule or ion that is a H+ donor
Base: Molecule or ion that is a H+ acceptor
HCl + H2O  H3O+ + Cl-
Does not include strong bases

4. Definitions of Acids and Bases
Lewis
The most general and least traditional
Defined by electrons instead of H+
Created by same scientist who electron-dot diagrams are named after
Acid: atom, ion, or molecule that accepts electron pair to form covalent bond
Base: atom, ion or molecule that donates and electron pair to form covalent bond
:NH3 + Ag+  [Ag(NH3)2]1+
BF3 + :NH3  BF3-NH3

6. Acids or Bases? C5H5N Mg(OH)2 HF NH3 H2CO3 H2SO4 KOH CH3NH2 HC2H3O2 HI
base (weak)
Mg(OH)2
base (strong) HF
acid (weak)
NH3
H2CO3
H2SO4
acid (strong)
KOH
base (strong)
CH3NH2
base (weak)
HC2H3O2
acid (weak) HI

7. Acid – Base Reactions
Identify the acids and bases of the following reactions
C6H5NH2 + H2O  C6H5NH3+ + OH-
B A
HNO3 + H2O  H3O+ + NO3-
A B
HCH3COO + H2O  H3O+ + CH3COO-
A B
BF3 + F-  BF4
A B

8. Acid-Base Reactions Amphoteric Substances
Can act as either acid or base depending on what they are mixed with
Example: Water, HSO4-

9. Conjugate Acid-Base Pairs Conjugate acids and bases are always created by a B-L reaction (are products)
Conjugate acid
A base that has gained a H+
Has an extra hydrogen
NH4+, C6H5NH3+, H3O+
Conjugate base
An acid that has lost a H+
Missing a hydrogen
Ex: H2PO4-, OH-, Cl-

10. Identify the parts of these reactions
C6H5NH2 + H2O  C6H5NH3+ + OH-
base acid CA CB
HNO3 + H2O  H3O+ + NO3-
acid base CA CB
HCH3COO + H2O  H3O+ + CH3COO-
acid base CA CB
NH3 + H2O  NH4+ + OH-
base acid CA CB