GO FURTHER
A
CHEMICAL ENGINEERING REVIEW SERIES 2023
STOICHIOMETRY AND PROCESS CALCULATIONS
REACTION SYSTEMS
1-2: The gas reaction A  2B + C occurs such that the entering stream contains 65% A, 15% B, 2% C
and 18% inerts by mole at 80oF, 14.7 psia. The exiting stream contains 4.76% A, 59.5% B, 27.14%, and
8.57% inerts at 320 oF, 25 psia .
1.
The percentage conversion of A:
a. 78.5%
b. 84.6%
c. 92.4%
d. 89.3%
2.
The ft3 product gas/ft3 feed gas
a. 1.74
b. 1.24
c. 2.31
d. 2.78
3-4: Consider the following pair of reactions.
A → 2B (desired)
A → C (undesired)
100 moles of A are fed to a batch reactor and the final product contains 10 mol of A, 160 mol of B and 10
mol of C. Calculate:
3.
percentage plant yield of B,
a. 80%
b. 70%
4.
the selectivity of B relative to C
a. 6
b. 8
c. 60%
d. 30%
c. 12
d. 33
C2H6  C2H4 + H2
C2H6 + H2  2CH4
take place in a continuous reactor at steady state. The feed contains 85.0 mole% ethane and
the balance inerts. The fractional conversion of ethane is 0.501, and the fractional yield of
ethylene is 0.867. Calculate the selectivity of ethylene to methane production:
5.
The reactions
a. 6.5
b. 4.2
c. 7.7
d. 9.3
COMBUSTION OF FUELS
6.
7.
8.
One hundred mol per hour of butane (C4H10) and 5000 mol per hour of air are fed into a combustion
reactor. Calculate the percent excess air:
a. 45.7%
b. 132%
c. 61.6%
d. 78.3%
Supposing that an unknown saturated hydrocarbon is burned under excess air and the Orsat analysis
is given by: 6.82% CO2, 1.364%CO, 0.546% H2, 9.15% O2 and balance N2. Determine:
The hydrocarbon is:
a. Ethane
b. Propane
c. Butane
d. Pentane
The percentage excess air used:
a. 40%
b. 50%
c. 60%
d. 70%
A gas fuel containing 30% methane and 70%ethane is burned such that the Orsat analysis of the
combustion gas gives 6.3% CO2, 1.938% CO, 8.36% O2 and balance nitrogen. Compute:
9.
The percentage excess air used:
a. 20%
b. 40%
c. 50%
d. 100%
10. The ratio kmols dry burner gas/kmols gas fuel
a. 12.45
b. 20.64
c. 34.11
11. The absorber for oxygen in the Orsat analyser is:
a. CuCl2
b. KOH
c. pyrogallol
d. 61.3
d. ammoniacal silver
Ultimate analysis:
C- 63%, H – 12%, O- 16%, ash- 9%
Proximate analysis: FC-39%, VCM-42%, Moisture-10%, ash-9%
1000 cubic meters of dry air at STP is provided per 100 kg of coal fired. The dry refuse contains 10.5% FC, 9% VCM,
80.2% ash. Only 80% of carbon burned are converted to CO2 the rest to CO. Find:
12. The %carbon in VCM:
a. 34.2%
b. 41.8%
c. 57.1%
d. 68.5%
13. Mass of refuse:
a. 11.2kg
c. 7.3 kg
d. 23.1 kg
b.17.3kg
14. Percentage excess air supplied:
a. 21.22%
b. 54.3%
c. 35.7%
d. 44.2%
15-16: A sample of anthracitic coal from Congo is analysed to contain 65% FC, 24% VCM, 10% Ash, 1% Moisture. The
calorific value is 32.78 MJ/kg. If the N and S contents are negligible, determine:
15. The % net H in the VCM:
a. 16.6%
b. 17.3%
16. % O of the fuel:
a. 5.64%
b. 6.72%
c. 22.5%
c. 2.12%
d. 7.5%
d. 3.41%
GO FURTHER
B
CHEMICAL ENGINEERING REVIEW SERIES 2022
STOICHIOMETRY AND PROCESS CALCULATIONS
REACTION SYSTEMS
1-2: In the vapour-phase hydration of ethane to ethanol, diethyl ether is produced as by-product. The
mixture consists of 60% ethylene, 3% inerts, and 37% water is sent to the reactor. The product analyzes
53.89% ethylene, 14.37% ethanol, 1.80% ether, 26.35% water and 3.59% inerts. Compute:
1.
Conversion of ethylene:
a.
67.8%
b. 34.5%
c. 24.3%
d. 56.8%
2.
Plant yield of ethanol:
a. 34%
b. 20%
c. 76%
d. 35%
3.
Supposing a reactor processes A and converted to B, but undesired product C is also formed:
AB+D
A  2C
The feed to the reactor contains 60% A, 15% B, 5% C, 3% D, and balance inerts. The exit stream
contains 14.29% A, 32.14%B and 12.14% inerts. Compute:
The conversion of A:
a. 70%
b. 75%
c. 67%
d. 51%
4. The plant yield:
a. 70%
b. 75%
c. 67%
5. The selectivity if B is the desired product:
a. 1
b. 2
c. 3
d. 51%
d. 4
COMBUSTION OF FUELS
6. A natural gas of an unknown composition is burned with air. An analysis of the product gas yields the
Orsat analysis of flue gas: 1.5% CO, 6.0% CO2, 8.2% O2, 84.3% N2. Determine the hydrocarbon fuel:
a. Ethane
b. Methane
c. Propane
d. Butane
7. Suppose that in a test 20 kg of propane (C3H8) is burned with 400 kg of air to produce 44 kg CO2
and 12 kg of CO. What was the percentage excess air?
a. 28%
b. 35%
c. 43%
d. 13%
8.
Ethane (C2H6) is burned with 50% excess air. The percentage conversion of the ethane is 90%;of
the ethane burned, 25% reacts to form CO and the balance to form CO2. Calculate the ratio of
water to dry fuel gas.
a. 0.456
b. 0.924
c. 0.113
d. 0.054
9.
What is the expected Orsat oxygen analysis of the complete combustion of pentane by200%
excess air?
a. 16.8%
b. 8.3%
c. 14.3%
d. 10.5%
10. The ultimate analysis of coal is 78% C, 6% H, 7% O, 3% S, 2% N, and 4% ash. The proximate
analysis is 65% FC, 4% moisture, 27% VCM, and 4 % ash. What is the percentage of net H from the
coal:
a. 7.88%
b. 5.12 kg
c. 6.74%
d. 10.21%
11-12: Sub-bituminous coal from Surigao Valley is analysed to contain 68% FC, 26% VCM, 5% Ash, and
1% Moisture. The higher heating value is 31.56 MJ/kg. If the N and S contents are negligible, determine:
11. The % net H in the VCM:
a. 13.7%
b. 18.9%
c. 16.4%
12. % O of the fuel:
a. 3.41%
c. 12.7%
b. 8.45%
d. 17.5%
d. 13.8%
13-14: A gas fuel containing 40% ethane(C2H6) and 60%propane(C3H8) is burned such that the Orsat
analysis of the combustion gas gives 4.95% CO2, 1.485% CO, 11.63% O2 and balance nitrogen.
Compute:
13. The percentage excess air used:
a. 50%
b. 100%
14. The ratio kmols dry burner gas/kmols gas fuel
a. 35.1
b. 64.2
c. 150%
c. 40.4
d. 200%
d. 73.5
GO FURTHER
A
CHEMICAL ENGINEERING REVIEW SERIES 2022
KINETICS AND REACTOR ENGINEERING
KINETICS AND REACTIONS ENGINEERING
1.
a.
The decomposition of NO2 to NO and O2 is studied in a batch inside a constant-volume reactor from an initial pressure of 1
atm of pure NO.
Time(min)
0
2
8
12
18
Total pressure(atm)
1
1.07
1.21
1.28
1.37
Determine the half-life of the reaction:
11 min
b. 10 min
c. 9 min
2.
Interpret the following kinetic data and determine the reaction order:
Time(h)
C(mol/Li)
a. First
3.
a.
4.
a.
5.
a.
6.
d. 12 min
0
0.2
b. second
0.5
0.182
c. zeroth
1.0
0.167
1.5
0.154
2.0
0.143
d. none of these.
The gas reaction, 3A  B occurs in a constant volume bomb such that 10% of A has been reacted in the first 50 seconds of
reaction. If the reaction is elementary, when will be the reaction 90% complete?
5.8 h
b. 1.3 h
c. 6.7 h
d. 1 month
The rate constant of the second-order reaction of a gas mixture containing 70% by of reactant A is 0.005/bar-s at 2 atm. What
is the half-life of the reaction?
321 sec
b. 89 sec
c. 213 s
d. 143 s
The third order reaction of 0.2 lbmol/ft3 of A occurs in a CSTR reactor such that the conversion is 50% when the liquid pumped
at 10 ft3/min. What rate should the pumping be so as to attain a 90% conversion in an plant-scale CSTR with 50 times the
volume of the pilot reactor?
2/7 ft3/min
b. 3/4 ft3/min
c. 3/7 ft3/min
d. 2/9 ft3/min
The series reaction X --(k1)--> Y –(k2)--> Z such that k1 = 0.127/h and k2 = 0.563/h. For a certain amount of X, what is the
time where the amount of Y is a maximum?
a. 9.6 sec
b. 2.1 sec
c. 3.4 sec
d. 7.1 sec
7.
A plug-flow is hooked with an MFR of five times the volume where a first order reaction occurs. If the conversion in the PFR is
20%, what is the overall conversion?
a. 45%
b. 62%
c. 89%
d. 72%
8.
A solution containing 0.4 mol/Li of reactant that decomposes in a second-order manner (half-life = 12 min) occurs in an MFR
followed by a PFR in series at. The conversion in the MFR is 20% and in the PFR is 80%. Determine the volume of
PFR/volume MFR:
a. 8
b. 12
c. 15
d. 20
9.
How many 210 Li –reactors connected in series are required for a 98% conversion of a first order conversion of lactose to
galactose and glucose(half-life = 35 minutes) at a rate of 10 Li/min?
a. 13
b. 11
c. 5
d. 8
10.
The conversion of diazoketine via Wolffe reaction isa competing system between the ketone and acid products. The rate
constant to ketone product is 0.074/min and to acid product is 0.0081/min. What is the conversion after 5minutes?
67%
b. 33%
c. 20%
d. 80%
a.
GO FURTHER
B
CHEMICAL ENGINEERING REVIEW SERIES 2022
KINETICS AND REACTOR ENGINEERING
KINETICS AND REACTIONS ENGINEERING
11.
Interpret the following kinetic data and determine the reaction order:
Time(h)
C(mol/Li)
a.
12.
a.
0
1.6
First
0.5
1.55
b. second
1.0
1.5
1.5
1.45
c. zeroth
2.0
1.4
d. none of these.
Determine the half-life of the reaction in problem no.1:
6h
b. 7 h
c. 8 h
d. 9 h
1.
A sample of gas P2O5 decomposes into solid P and O2 with a firs-order rate constant of 2.31 x1014 exp[ -13,400/T]/s. At t
= 0, pure P2O5 is admitted into a constant temperature and volume reactor with an initial pressure of 1 atm. After 1 min,
what is the total pressure of the reactor? T = 400 K .
a. 3.53 atm
b. 2.98 atm
c. 2.12 atm
d. 1.72 atm
2.
The gas reaction, A  2B occurs in a constant volume bomb such that the pressure is 3 atm in the first 5 minutes of
reaction with pure A present to start at 2 atm. If the reaction is elementary, when will be the reaction 99%complete?
b. 35
b. 54 min
c. 21 min
d. 33 min
3-4: Supposing that the reaction of the decomposition of CO to solid C and O2 at 500degC in a constant volume reactor
such that the initial pressure of CO is 1 atm. The decomposition is first order with k = 0.21/h at 100degC, and k = 0.64/h at
200degC :
3.
The rate constant at 500degC is nearly:
b. 5.62
a. 2.15
c. 1.74
d. none
4.
The pressure in the reactor at 80% conversion of CO:
a. 0.6 atm
b. 0.7 atm
c. 0.8 atm
d. none
5.
The time to reach 80% conversion is nearly:
a.
17 min
b. 28 min
c. 3 min
d. none
6.
The rate constant of the third-order reaction of equimolar mixture of NO2 and Cl2 is 0.082/atm2-s at 1 atm. What is thehalflife of the reaction?
b. 73 sec
b. 153 sec
c. 42 sec
d. none
7.
The series reaction X --(k1)--> Y –(k2)--> Z such that k1 = 0.053/s and k2 = 0.101/s. For a certain amount of X, what is
the time where the amount of Y is a maximum?
a. 8.5 sec
b. 7.4 sec
c. 13.4 sec
d. 16.2 sec
8.
The inversion of mannose in a solution occurs as an equilibrium reaction such that the kforward = 1.5 x 10-3/min and kreverse =
3.4 x 10-4/min. At what time will the 90% of the equilibrium conversion be attained?
a. 21 mins
b. 1.4 h
c. 781 sec
d. none
9.
A varying-volume bomb reactor is charged with 20 mols of air and 20 of hydrogen and heated to produce ammonia. The
ammonia reaction is approximately first order such that the reactor volume dropped by 20% in 30 minutes. Determine the
half-life of the reaction:
a. 58 min
b. 74 min
c. 41 min
d. none
10. The second order reaction of 0.5 mol/Li of S occurs in a pilot back-mix reactor such that the conversion is 70% when the
liquid pumped at 30 Li/min. What rate should the pumping be so as to attain a 95% conversion in an plant-scale CSTR
with 5 times the volume of the pilot reactor?
b. 3.1 Li/min
b. 7.4 Li/min
c. 1.5 Li/min
d. none.
11. The 65% conversion demethylation of phenoxyacetate(A) in antibiotic production is a first order reaction that is occurred
in a 530- cu. ft plug-flow reactor at such that a solution containing A is fed at 40 gal/min. What volume of a corresponding
MFR is required for the same conversion and feeding conditions?
a.
1200 ft3
b. 632 ft3
c. 1088 ft3
d. 940 ft3