Biomedical Engineering Reference
In-Depth Information
PROBLEMS
6.1.
The gas-phase decomposition of azomethane (AZO) to give ethane and nitrogen:
ð
CH
3
Þ
2
N
2
/
C
H
6
þ
N
2
2
is believed to progress in the following fashion:
2
2 ð
CH
3
Þ
2
N
2
%ð
CH
3
Þ
2
N
2
þ½ð
CH
3
Þ
2
N
2
/
½ð
3
Þ
2
6
þ
CH
N
C
H
N
2
Derive the rate of formation of ethane (C
2
H
6
) that is consistent with this mechanism.
Clearly define the symbols you use and state your assumptions.
2
6.2.
The reaction to form NO: N
2
þ
2 NO, in high-temperature combustion processes,
is thought to proceed by the following elementary steps:
O
2
/
k
1
%
O
2
O
2
k
1
k
2
NO
N
2
þ
O
/
þ
N
k
3
NO
O
2
þ
N
/
þ
O
Find a reasonable reaction rate for the overall reaction.
6.3.
The gas-phase dehydrogenation of ethane to ethylene
C
H
6
/
C
H
4
þ
H
2
2
2
Proceeds through the elementary reaction steps
k
1
C
C
H
6
þ
H
$/
H
5
$ þ
H
2
2
2
k
1
6
%
C
H
C
H
5
$ þ
H
$
2
2
k
2
k
3
C
C
H
5
$/
H
4
þ
H
$
2
2
(a)
Identify the initiation, propagation, and termination steps.
(b)
Find a reasonable expression for the overall reaction rate.
(c)
The bond energy of ethane is 104 kcal/mol, and the propagation steps have very
low activation energies. What is the approximate activation energy of this reaction?
6.4.
The Goldschmidt mechanism (Smith, 1939) for the esterification of methyl alcohol (M)
with acetic acid (A) catalyzed by a strong acid (e.g. HCl) involves the following steps:
H
þ
/
OH
2
ð
M
þ
CH
C
Þ
; rapid
(1)
3
O
þ
; slow
A
þ
C
/
CH
COOCH
3
ð
E
Þþ
H
(2)
3
3
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