DEPARTMENT OF CHEMICAL ENGINEERING
INSTRUCTIONAL PROGRAMME: BENG TECH CHEM ENG
INSTRUCTIONAL OFFERING : REACTION ENGINEERING
PAPER NUMBER : TEST 1
SUBJECT CODE : RCNE101
DATE : 06 MAY 2021
DURATION : 90 MINUTES
TOTAL MARKS : 60
NUMBER OF PAGES :4
EXAMINER/S : DR T.P MAHLANGU
MODERATOR : MR N BRIJMOHAN
INSTRUCTION/ REQUIREMENTS
1. ANSWER ALL QUESTIONS
2. WRITE YOUR NAME AND STUDENT NUMBER ON ANSWERSHEETS
3. MARKS WILL BE DEDUCTED FOR UNTIDY AND ILLEGIBLE ANSWERS
1
, QUESTION ONE
X 0 0.1 0.2 0.4 0.6 0.75 0.9
-rA
0.5 0.42 0.38 0.15 0.109 0.082 0.04
(mol/m3.s)
A reaction A B + C is carried out in a CSTR where pure A enters at 8 mol/min. Using the reaction
data in the table above,
a) Calculate the volume required to reach 85% conversion of A.
b) Graphically display the area required to achieve a conversion of 85%.
c) If the same reaction was carried out in a PFR, what would the volume be for a conversion of
60%?
15 marks
QUESTION TWO
The rate constant for a second-order reaction at 85 degrees Celsius is 2.5 and the activation energy
is 20 KJ/mole. What are the units of the rate constant? At what temperature would the rate be triple
(of the rate at 85 degrees Celsius) for this reaction?
12 marks
QUESTION THREE
A gas phase reaction
2A + B ---> C + D
takes place in a PFR at a constant pressure of 25 atm and temperature of 350 K. The feed at a flow
rate of 5 dm3/min is 20% A and 80% B. Determine the PFR volume. The reaction is irreversible and
follows an elementary rate law. X = 0.9 and the rate constant is k = 8 dm6/mol2.s. Vo = 5dm3.
a) Construct a stoichiometric table.
b) Determine the volume required to reach the above-mentioned conversion.
c) Calculate the time it takes to reach the conversion.
33 Marks
2
INSTRUCTIONAL PROGRAMME: BENG TECH CHEM ENG
INSTRUCTIONAL OFFERING : REACTION ENGINEERING
PAPER NUMBER : TEST 1
SUBJECT CODE : RCNE101
DATE : 06 MAY 2021
DURATION : 90 MINUTES
TOTAL MARKS : 60
NUMBER OF PAGES :4
EXAMINER/S : DR T.P MAHLANGU
MODERATOR : MR N BRIJMOHAN
INSTRUCTION/ REQUIREMENTS
1. ANSWER ALL QUESTIONS
2. WRITE YOUR NAME AND STUDENT NUMBER ON ANSWERSHEETS
3. MARKS WILL BE DEDUCTED FOR UNTIDY AND ILLEGIBLE ANSWERS
1
, QUESTION ONE
X 0 0.1 0.2 0.4 0.6 0.75 0.9
-rA
0.5 0.42 0.38 0.15 0.109 0.082 0.04
(mol/m3.s)
A reaction A B + C is carried out in a CSTR where pure A enters at 8 mol/min. Using the reaction
data in the table above,
a) Calculate the volume required to reach 85% conversion of A.
b) Graphically display the area required to achieve a conversion of 85%.
c) If the same reaction was carried out in a PFR, what would the volume be for a conversion of
60%?
15 marks
QUESTION TWO
The rate constant for a second-order reaction at 85 degrees Celsius is 2.5 and the activation energy
is 20 KJ/mole. What are the units of the rate constant? At what temperature would the rate be triple
(of the rate at 85 degrees Celsius) for this reaction?
12 marks
QUESTION THREE
A gas phase reaction
2A + B ---> C + D
takes place in a PFR at a constant pressure of 25 atm and temperature of 350 K. The feed at a flow
rate of 5 dm3/min is 20% A and 80% B. Determine the PFR volume. The reaction is irreversible and
follows an elementary rate law. X = 0.9 and the rate constant is k = 8 dm6/mol2.s. Vo = 5dm3.
a) Construct a stoichiometric table.
b) Determine the volume required to reach the above-mentioned conversion.
c) Calculate the time it takes to reach the conversion.
33 Marks
2
