ACIDS AND BASES

Chemistry

Arrhenius Acids & Bases

Arrhenius Acids Donate H+ to the

solution

HNO3 H+ + NO3-

Arrhenius Bases Donate OH- to the

solution

NaOH Na+ + OH-

H2O

H2O

Brønsted-Lowry Theory

Acid: proton (H+) donor HCl H2SO4

Base: proton (H+) acceptor NaOH NH3

Questions…

1. Which can be a B-L acid?

a) HNO3

b) Cu2+

c) HCO3-

2. Which can be a B-L base?

a) OH-

b) H2O

c) HCO3-

Conjugate Pairs

All B-L acid/base reactions have the following set-up:

HA + B ⇌ A- + HB+

Conjugate Pairs: HA & A-

B & HB+

Conjugate Pair

Conjugate Pair

3

Conjugate Acid/Base Pair Examples

Some Conjugate Acid-Base Pairs

Acid Base

HCl Cl–

H2SO4 HSO4–

H3O+ H2O

HSO4– SO4

2–

CH3COOH CH3COO–

H2CO3 HCO3−

HCO3– CO3

2–

NH4+ NH3

H2O OH–

Conjugate Acids & Bases Practice1. Determine the

conjugate acids for the following:

1. CN-

2. H2PO4-

3. PO43-

4. H2O

5. NH3

Determine the conjugate bases for the following:

a. H3O+

b. H2PO4-

c. H3PO4

d. HBre. H2SO4

Predict the following:

1. HNO3 + NH3

2. NH4+ + PO4

3-

3. H3O+ + CO32-

4. CH3COOH + H2O

Lewis’s Definition of Acids & Bases Defines

acids/bases in terms of e- pairs

Lewis Acid: e- pair acceptor

Lewis Base: e- pair donor

Lewis Acids & Bases

Lewis Acid: Must be able to

accept lone e- pairs (incomplete octet)

B, Be, Transition Metals

Lewis Base: Must have lone e-

pairs

Dative bond: Shown with

arrows to indicate donation of e- pairs

Complex Ions Lewis acids will

often form complex ions

Attached bases are called ligands

Acid/Base Definition Summary

Acid-Base Definitions

Type Acid Base

Arrhenius H+ producer OH– producer

Brønsted-Lowry H+ donor H+ acceptor

Lewis electron-pair acceptor electron-pair donor