Textbook Chapters for Exam 3
You still need to know many of the concepts and calculations from Chapter 7 (type 1 problems). Plus, exam 3, WILL have
polyprotic acids on it in some form. Polyprotics were introduced in Chapter 7. Also fraction of species (plus charge and mate
rial balance) was in Chapter 7 as well. All of Chapter 8 (although you can skip section 3) is valid for exam 3. You’re responsible
for any material covered in class whether it was on the homework or not. This review sheet covers most everything we have
done.
Also remember that no equations are given on the exams. Values for equilibrium constants are given where needed.
Chapter 7 – Type 1 problems and Poly
protic acids and bases
•
You STILL have to be able to solve type 1 problems (like on
exam 2). Type 1 problems are the starting point and the
equivalence point on pH curves (titrations).
•
Be able to write the appropriate stepwise reactions for poly
protic acids and bases. Know how to calculate the concen
trations of various deprotonated species for polyprotic
acids and bases.
•
Remember
the numbering for polyprotic acids and their con
jugates run in opposite directions.
The first proton off a
diprotic acid (
K
a1
) is always the LAST proton going ON to
the corresponding conjugate base (
K
b2
).
For a triprotic acid: H
3
A
±
H
+
+
H
2
A

matches up with
K
a1
The conjugate reaction is H
2
A

+ H
2
O
±
H
3
A
+
OH

and matches up with
K
b3
.
The relationship between the two is
K
a1
·
K
b3
=
K
w
.
•
Know what the dominant species are at various pH’s for any
acid or base (mono or polyprotic). Yes, you do have to
know the
K
a
’s or
K
b
’s, but those would be given. This task
is much easier when you know about fraction of species
and the plotting of it versus pH.
•
SECTION 7.9
This section is mainly about very dilute solu
tions. The take home lesson in this section is that water
itself contributes about 10
7
M H
+
to solutions  if your
concentrations you mix are less than that, then the contri
bution from water is the main one.
Charge Balance:
Know how to write out the charge bal
ance for any solution (see page 262).
Material Balance:
Know how to write out the material
balance for any solution. Note that it is all the species in
the material balance that make up a fraction of species
diagram.
Fraction of Species
•
Know about Fraction of Species and the way the plot looks
and how you would use it to answer various questions
about what species is the major species at a given pH. See
my “Fraction of Species” help sheet. Below is a fraction of
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 Spring '07
 Holcombe
 pH, buffer solution, Dr. McCord CH302

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