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TRANSCRIPT
I. Introduction to
Acids & Bases
Unit 14- Acids & Bases
A. Properties
electrolytes electrolytes
turn litmus red
sour taste
react with metals
to form H2 gas
slippery feel
turn litmus blue
bitter taste
ChemASAP
vinegar, milk, soda,
apples, citrus fruits
ammonia, lye,
antacid, baking soda
3 Definitions of Acids
Arrhenius: acids are substances which
produce H+ ions in water.
Brønsted-Lowry: acids are substances
which donate H+ ions to other
substances.
Lewis: acids are substances which
accept electron pairs from other
substances.
3 Definitions of Bases
Arrhenius: Bases are substances that
produce OH- ions in water.
Brønsted-Lowry: Bases are substances
that accept H+ ions from other
substances.
Lewis: Bases are substances that
donate a pair of electrons to another
substance.
B. Definitions
Brønsted-Lowry
HCl + H2O Cl
–+ H
3O
+
•Acids are proton (H+) donors.
•Bases are proton (H+) acceptors.
conjugate acidconjugate base
baseacid
B. Definitions
H2O + HNO
3 H
3O
+ + NO
3
–
CBCAAB
B. Definitions
Lewis
•Acids are electron pair acceptors.
•Bases are electron pair donors.
Lewis base
Lewis acid
Unit 14- Acids & Bases
II. pH
A. Ionization of Water
H2O + H2O H3O+ + OH-
Kw = [H3O+][OH-] = 1.0 10-14
A. Ionization of Water
Find the hydroxide ion concentration of
3.0 10-2 M HCl.
[H3O+][OH-] = 1.0 10-14
[3.0 10-2][OH-] = 1.0 10-14
[OH-] = 3.3 10-13 M
Acidic or basic? Acidic
pH = -log[H3O+]
B. pH Scale
0
7INCREASING
ACIDITYNEUTRAL
INCREASING
BASICITY
14
pouvoir hydrogène (Fr.)
“hydrogen power”
B. pH Scale
pH of Common Substances
B. pH Scale
pH = -log[H3O+]
pOH = -log[OH-]
pH + pOH = 14
III. Titration
Unit 14- Acids & Bases
A. Neutralization
Chemical reaction between an acid and
a base.
Products are a salt (ionic compound)
and water.
A. Neutralization
ACID + BASE SALT + WATER
HCl + NaOH NaCl + H2O
HC2H
3O
2+ NaOH NaC
2H
3O
2+ H
2O
• Salts can be neutral, acidic, or basic.
• Neutralization does not mean pH = 7.
weak
strong strong
strong
neutral
basic
Acid-Base Titrations
A titration is a volumetric technique
often involving acid-base
neutralizations.
It often involves reacting one solution
of known concentration, with another
of unknown concentration.
Let’s take a look at how a titration is
performed.
Then we’ll look at calculations.
Equivalence point (endpoint)
• Point at which equal
amounts of H3O+ and OH-
have been added.
• Determined by…
• indicator color change
B. Titration
• dramatic change in pH
B. Titration
moles H3O+ = moles OH-
MVn = MVn
M: Molarity
V: volume
n: # of H+ ions in the acidor OH- ions in the base
B. Titration
42.5 mL of 1.3M KOH are required to
neutralize 50.0 mL of H2SO4. Find the
molarity of H2SO4.
H3O+
M = ?
V = 50.0 mL
n = 2
OH-
M = 1.3M
V = 42.5 mL
n = 1
MV# = MV#
M(50.0mL)(2)
=(1.3M)(42.5mL)(1)
M = 0.55M H2SO4