Environmental Engineering Reference
In-Depth Information
5.36
2
The decomposition of N
2
O
5
to NO
2
in the gas phase occurs via the
following reaction scheme:
k
f1
k
b1
NO
2
+
NO
3
,
NO
2
+
NO
3
k
2
N
2
O
5
−→
NO
+
O
2
+
NO
2
,
NO
+
NO
3
k
3
−→
2NO
2
.
Derive the following equation for the overall decomposition rate of N
2
O
5
by using the PSSA to show that
−
d
[
N
2
O
5
]
/
d
t
=
k
tot
[
N
2
O
5
]
. Identify the
expression for
k
tot
.
5.37
3
A complete and general mechanism for enzyme catalysis should include a
reversible decomposition of the E-S complex:
E
+
S
k
1
k
−
1
E
−
S
k
2
k
−
2
E
+
P
Derive an equation for the rate of product formation. Contrast it with
that derived in the text where reversible decomposition of E-S was not
considered.
5.38
2
Some substrates can bind irreversibly to either an enzyme or the enzyme-
substrate complex and interfere with enzymatic reactions. These are called
inhibitors
and are of two types:
(a) Derive the rate expressions for product formation in each case and
sketch the behavior as Michaelis-Menten plots.
(b) The hydrolysis of sucrose is said to be inhibited by urea. The rate
data for the same are given below:
[S] (mol/L)
r
(mol/L s)
r
(mol/L s) with
[
I
]=
2M
0.03
0.18
0.08
0.06
0.27
0.11
0.10
0.33
0.18
0.18
0.37
0.19
0.24
0.37
0.18
What type of an inhibitor is urea?
5.39
1
The uptake of CO
2
in water and subsequent dissociation into bicarbon-
ate ion is shown to be accelerated by an enzyme called
bovine carbonic
anhydrase
. The following data are provided on the initial rate of the
reaction:
CO
2
(aq)
+
H
2
O(aq)
E
−→
H
+
(aq)
+
HCO
3
(aq).
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