8.18: Untitled Page 207
- Page ID
- 18340
Chapter 8
Figure 8.8. Accidental overflow from a stirred tank reactor Section 8.2
8‐9. Show how Eq. 8‐27 can be used to derive Eq. 8‐28.
8‐10. A perfectly mixed batch reactor is used to carry out the reversible reaction described by
k 1
Chemical kinetic schema:
A E
B
(1)
k 2
and the use of mass action kinetics provides a chemical reaction rate equation given by
Chemical reaction rate equation:
R
k c c
k c
(2)
A
1 A E
2
B
second order
first order
reaction
decomposition
If species E is present in great excess, the concentration c will undergo E
negligible changes during the course of the process and we can define a pseudo first order rate coefficient by
k
k c
(3)
1
1 E
Given initial conditions of the form
I.C.
o
o
c
c ,
c
c ,
t 0
(4)
A
A
B
B
use the pseudo first order rate coefficient to determine the concentration of species A and B as a function of time.
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8‐11. When molecular species A and B combine to form a product, one often adopts the chemical kinetic schema given by
k
A B
products
(1)
Use of mass action kinetics then leads to a chemical kinetic rate equation of the form
R
k c c
(2)
A
A B
One must always look upon such rate expressions as hypotheses to be tested by experimental studies. For a homogeneous, liquid‐phase reaction, this test can be carried out in a batch reactor which is subject to the initial conditions I.C.1
o
c
c , t 0
(3)
A
A
I.C.2
o
c
c , t 0
(4)
B
B
Use the macroscopic mole balances for both species A and B along with the stoichiometric constraint
R
R
(5)
A
B
in order to derive an expression for c as a function of time. In this case one is A
forced to assume perfect mixing so that c c can be replaced by c c .
A B
A
B
8‐12. A batch reactor illustrated in Figure 8.12 is used to study the irreversible, decomposition reaction
k
A
products
(1)
The proposed chemical kinetic rate equation is
R
k c
(2)
A
A
and this decomposition reaction is catalyzed by sulfuric acid. To initiate the batch process, a small volume of catalyst is placed in the reactor as illustrated in Figure 8.12. At the time, t 0 , the solution of species A is added at a volumetric
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