Assignment 1 (Subject: Ch.E.
401 Chemical Reactor Design)
(Due Date: 13 October 2020)
Review Problems
Q1
Suppose that a gaseous reaction between A and B is studied kinetically by making isothermal
measurements of the half-life period for several initial compositions of reactants. The results for each of
four different initial conditions are as follows:
(PA)o , mmHg 500 125 250 250
(PB)o , mmHg 10 15 10 20
(t1/2)B , min 80 213 160 80
If the rate is first order with respect to component A and second order with respect to B. what is the
numerical value of specific rate constant.
Q2
Find the rate equation for A+B R + S where CBo = 3CAo
t (hr) 0 1 2 4 6
CA (mol/lit) 500 225 110 30 10
Q3
The aqueous reaction for A R + S proceed as follows:
With CRo = 0 and CS0 = 55 mol/lit. Find the rate equation for this reaction.
t (min) 0 36 65 100 160 ∞
CA (mol/lit) 0.4823 0.1453 0.1216 0.1025 0.0795 0.0494
Q4
At high temperature Acetylene polymerize to produce an average tetramer complex as following
4(C2H2) (C2H2)4. In a constant Volume batch reactor, show that at 1atm, and 550°C pure
acetylene is 0.9% polymerized in 1sec and this reaction follows 2nd order kinetics. Find a rate equation in
units of moles, liter, and seconds to represent the pyrolysis.
Q5
An aqueous feed of reactants A and B (400 lit/min, 10mmolA/ lit, 2mmolB/lit) is to be
converted to product in a mixed flow reactor. The kinetics of the reaction is represented by:
A+B R -rA = 200 CA CB mol / lit.min
i. Find the reactor size needed for 99.9% conversion of A.
ii. Find the conversion in a 4 liter reactor.
Q6
Gaseous reactant A decomposes as follows:
A 3R, -rA = (0.6 min-1) CA
i. Find the conversion of a pure A feed (VO = 180 lit/min, 240 mmol/lit) to a 600 liter
mixed flow reactor.
ii. Find the volumetric flow rate into and out of a 50 liter mixed flow reactor which would
lower the concentration of A in a pure A feed from CAO = 600 mmol/lit to CA = 60
mmol/lit.
iii. Find the volume of mixed flow reactor needed for 50% conversion of a 50% A and 50%
inert feed (VO = 360 lit/min, CAO = 960 mmol/lit)
iv. Find the conversion of A in a 50% A and 50% inert feed (Vo=180 lit/min, CAO = 300
mmol/lit) to a 1m3 mixed flow reactor.
Q7
Gaseous A (1000 mmol/lit) enters a plug flow reactor (V=10 cm3) and there reacts isothermally
(A + B → 3R + S).For various feed rates the following exit concentrations are measured. From
this data find the rate of reaction at CA = 250 mmol/lit.
V (cm3/sec) 0.5 3 16 60
CAf (mmol/lit) 10 50 200 500
Q8
Aqueous reactant A at 1000 mmol/lit enters a plug flow reactor (V=100 cm3), reacts to form
products (A → 2R), and the exit concentration is measured at various feed rates. From the
following data find the rate of reaction at CA =300 mmol/lit.
V (cm3/sec) 40 60 120 300
CAf (mmol/lit) 80 190 435 715
Q9
Aqueous reactant A at 1000 mmo1/lit enters a plug flow reactor (V=24 cm3) , reacts away (A
→ R) , and exit concentration is measured at various feed rates. From the following data find the
rate of reaction at CA = 400 mmol/lit.
V (cm3/sec) 1 6 24
XA 0.96 0.80 0.50
Q10
The reaction of A to R is run a number of temperature levels in a 1litre mixed flow reactor. The
feed is introduced at v = 1lit/min at a concentration 100mmol/lit and the outlet concentration is
measured. Find the complete rate equation for the reaction from the following data.
i. Reaction is first order
T (°C) 16 25 31
CA (mmol/lit) 55.7 35.2 24.1
ii. First order reaction
T (°C) 4 12 24 30
CA (mmol/lit) 8.8 5.9 3.4 2.6
