Transcript Acid Base Chemistry-Part I

Acid/Base Chemistry
Part I
CHEM 2124 – General Chemistry II
Alfred State College
Professor Bensley
Learning Objectives
 Define acid and base according to the Arrhenius
concept.
 Define acid and base according to the
Brønsted–Lowry concept.
 Define the term conjugate acid-base pair.
 Identify acid and base species.
 Define amphiprotic species.
 Understand the relationship between the
strength of an acid and that of its conjugate
base.
Learning Objectives
 Decide whether reactants or products are
favored in an acid-base reaction.
 Define the ion-product constant for water.
 Calculate the concentrations of H3O+ and OHin solutions of strong acids or bases.
 Define pH and calculate the pH from
hydronium-ion concentrations.
 Calculate the hydronium-ion concentration
from pH.
Opener
Introduction to Acids and Bases
A. Arrhenius Definition
B. The Brønsted–Lowry Definition
Acid/Base Chemistry
C. Proton Transfer Reactions
gain of H+
H A
acid
+
B
base
loss of H+
A − +
H B+
conjugate conjugate
acid
base
Acid/Base Chemistry
D. Relating Acid and Base Strength
When a covalent acid dissolves in water, the proton
transfer that forms H3O+ is called dissociation.
A strong acid, HCl, is
completely dissociated
into H3O+(aq) and Cl−(aq).
A weak acid contains
mostly undissociated
acid, CH3COOH.
Acid and Base Strength
Relating Acid and Base Strength
A strong base, NaOH, is
completely dissociated
into Na+(aq) and −OH(aq).
A weak base contains
mostly undissociated
base, NH3.
Acid/Base Chemistry
E. Acid/Base Equilibrium
A Brønsted–Lowry acid–base reaction represents
an equilibrium.
H A
acid
+
B
base
H A
+
B
stronger
stronger
acid
base
A − +
H B+
conjugate conjugate
acid
base
A − +
weaker
base
H B+
weaker
acid
Acid/Base Chemistry
F. Dissocciation of Water
loss of H+
H
O
H + H
acid
O
base
H
−
O
H
conjugate
base
gain of H+
Kw =
+
H
+
H
O
H
conjugate
acid
Acid/Base Chemistry
F. Calculating pH
pH = −log [H3O+]
Focus on the Human Body
The pH of Body Fluids
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