1
Comprehensive Exam Review
12/03/2009
Structure & Properties of Water
Bent geometry, OH bond length of 0.958Å
Can form Hydrogen bonds
Henderson  Hasselbalch equation
]
[
]
][
[
HA
A
H
K
−
+
=
From
]
[
]
[
]
[
−
+
=
A
HA
K
H
Rearrange
Take ()Log of each
]
[
]
[
log
log
HA
A
K
pH
−
+
−
=
]
[
]
[
log
HA
A
pK
pH
−
+
=
The 6
step approach
1. Write the Henderson + Hasselbalch equation.
2. Write the acid base equation
3. Make sure either an H
+
or OH

is in the equation.
3. Find out what you are solving for
4. Write down all given values.
5. Set up equilibrium conditions.
6. Plug in H + H equation and solve.
What is the pH of a solution of that contains 0.1M
CH
3
COO

and 0.9 M CH
3
COOH?
1
) pH = pK + Log
[A

]
[HA]
2) CH
3
COOH
CH
3
COO

+ H
+
3) Find pH
4) pK = 4.76
A

= 0.1 M
HA = 0.9 M
5) Already at equilibrium
6)
X = 4.76 + Log 0.1
0.9
Log 0.111 =
.95
X = 4.76 + (.95)
X = 3.81
Amino Acids
You must know Table 4.1 p7677:
Their
names
Their
structure
Their
three letter code
h i
l
d
Their
one letter code
Tyrosine, Tyr, Y, aromatic, hydroxyl
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