Chapter 5: Isothermal Reactor Design: Conversion
Pressure and Reaction Orders
A. Which of the following reaction orders is most affected by presure drop?
zero order
first order
third order
out of order
Solution A
B. For negative reaction orders (e.g.n=-1), pressure drop
will:
increase the conversion
decrease the conversion
not affect the conversion
produce negative conversion
over and above what it would be if there were no pressure drop.
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A. Which of the following reaction orders is most affected by presure drop?
a) zero order
b) first order
c) third order
d) out of order
Solution
(A) zero order
\(-r_A = k\)
(B) first order
\(V = \frac{F_{A0} X}{-r_A}\)
\(-r_A = k_A\)
(C) third order
\(-r_A = kC_{A0}^3 (1 - X)^3 \left(\frac{P}{P_0}\right)^3\)
\(V = \frac{F_{A0} X}{k_A}\)
Answer: (C)
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B. For negative reaction orders (e.g.n=-1), pressure drop will:
a) increase the conversion
b) decrease the conversion
c) not affect the conversion
d) produce negative conversion
over and above what it would be if there were no pressure drop.
Solution
\(V = \frac{C_{A0} \, v_0 \, X}{k_A}\)
\(\frac{V}{v_0} = \tau = V = \frac{C_{A0} \, X}{k} = \frac{\left(0.5 \, \text{mol}/\text{dm}^3\right)(0.9)}{0.01 \, \text{mol}/\text{dm}^3}\)