CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
SAMPLE QUESTIONS
CHE CALCULATIONS
Compiled by: Engr. Albert D.C. Evangelista
MULTIPLE CHOICES:
1. Which of the following statements is incorrect?
(A) Recycling in a process stream helps utilize the valuable reactants to the maximum with
minimum loss of reactants.
(B) Recycling in a process does not help in getting a higher extent of reaction.
(C) Sometimes, in chemical processes, a part of the outlet stream is rejected as waste to keep
the impurity level in the system within limits. This phenomenon is termed as purging.
(D) Recycling is exemplified by refluxing back a part of the distillate to the distillation
column to maintain the quantity of liquid within the column.
2. A 'limiting reactant' is the one, which decides the ______________ in the chemical reaction.
(A) rate constant
(C) conversion
(B) time
(D) equilibrium constant
3.
It is used to indicate the strength of the sugar solution.
(A) Baume scale
(C) Twaddell scale
(B) API scale
(D) Brix scale
4. Which of the following statements is correct?
(A) Combined Water (CW) is the oxygen in the coal (present in moisture) is treated as though
it were already combined with carbon
(B) Proximate Analysis is based on the differences in the volatility of the components of the
coal.
(C) Proximate analysis is less expensive and is normally substituted for ultimate analysis.
(D) A higher cetane number indicates lower fuel efficiency
5. Soyabean seed oil is extracted with hexane in a batch extractor. The flaked seeds contain
18.2% oil, 69.5% solid, and 12.3% moisture. At the end of the process, the cake is separated
from the hexane oil mixture. The cake analysis yields 0.8% oil, 88.2% solids, and 11.0%
moisture. All percentages are by weight. The percentage recovery of oil is close to
(A) 91
(C) 97
(B) 88
(D) 94
6. It is the fraction of the feed or fraction of certain constituents of the feed that is converted into
products.
(A) selectivity
(C) conversion
(B) quality
(D) bypass
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
7. Which of the following statements is incorrect?
(A) Using pulverized coal in a boiler furnace provides better combustion.
(B) Recycling in a process does not help in getting a higher extent of reaction.
(C) Incomplete combustion of a fuel is characterized by the high carbon monoxide in the
flue gas.
(D) When steam is passed over coal resulting in the endothermic reaction, it is represented
by C + H2O = CO + H2, it is called the gasification of coal.
8. It is the conversion of the limiting reactant and may be defined as the ratio of the amount of
the limiting reactant that has undergone chemical transformation to the amount that was
available for the reaction.
(A) selectivity
(C) quality
(B) yield
(D) degree of completion
9. It is the ratio of the actual moles of the desired product to the moles which would have been
resulted if the reactant was converted entirely to form the desired products.
(A) selectivity
(C) quality
(B) yield
(D) degree of completion
10. A certain product stream consisting of 4.0% P (by weight), 22% M (by weight), and 28% R
(by weight) in water at 48,000 lbm/hr is produced by mixing two streams, A and B. Stream
A is produced in mixer 1 by mixing two streams, J1 and J2. Stream J1 is 99% M (by weight)
in water, and stream J2 is 95% P (by weight) in water. Stream B is 100% R. There is no M
or P in stream B. The percentage of component P in stream A is most nearly
(A) 5.11
(C) 12.31
(B) 21.33
(D) 15.13
11. It is another term used to indicate the relative prominence of side reactions over the desired
reactions. It is defined as moles of the reactant converted to the desired product divided by
moles of the reactant converted to undesired products.
(A) selectivity
(C) quality
(B) yield
(D) degree of completion
12. It is defined as the degree to which a reaction has advanced.
(A) selectivity
(C) yield
(B) order of reaction
(D) extent of reaction
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
13. A flow splitter (S1) divides a liquid stream flowing at 1000 lbmol/hr into three streams as
shown. The stream flow rates are regulated so that the flow rate in stream 2 is two times the
flow rate in stream 3 and the flow rate in stream 3 is one-third of the flow in stream 4. The
second splitter (S2) divides stream 3 into two streams flowing at equal flow rates. Steam 6 is
combined with stream 4 in mixer 1 to produce stream 7.
The flow (kgmol/h) in stream 7 is most nearly
(A) 456
(C) 583
(B) 334
(D) 265
14. A bypass stream in a chemical process is useful because it
(A) increases the yield of products
(C) facilitates better control of the process
(B) improves the conversion
(D) to make the heartbeats
15. A system with this is one in which a stream leaving a processing unit is partly returned to the
same unit for reprocessing or reusing.
(A) Recycle
(C) Purge
(B) Bypass
(D) Blowdown
16. Milk contains around 5% fat. To prepare 100kg of skimmed milk which is found to contain
0.1% fat, the fresh milk is sent to a filter. Assuming that no liquid milk adheres to the solid
fat upon removal, calculate the mass of the removed fat.
(A) 5.16 kg
(C) 6.15 kg
(B) 5.61 kg
(D) 6.51 kg
17. The loss in weight when the coal sample is heated in a covered crucible for about 7 minutes
at 950°C minus the weight of the moisture.
(A) Moisture
(C) Volatile combustible matter
(B) Fixed carbon
(D) Ash
18. It gives the composition as the percentage by weight of the various elements such as C, H,
N, 0, S, etc., and the ash.
(A) Modified analysis
(C) ultimate analysis
(B) Orsat analysis
(D) proximate analysis
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
SITUATION FOR PROBLEMS 19-20
A saturated solution of salt is made by agitating 500kg salt in 1500kg water. The solubility of the
salt is 0.3kg per kg water. Upon filtration, 0.5kg of the solution adheres to every kg of
undissolved salt. Calculate the following:
19. Weight of the filtrate
(A) 50 kg
(B) 75 kg
(C) 1925 kg
(D) 1950 kg
20. Weight of dry salt recovered on the drying of the wet filter cake.
(A) 55.77 kg
(C) 442.43 kg
(B) 57.57 kg
(D) 444.23 kg
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
SITUATION FOR PROBLEMS 21-23:
Pyrite analyzing 78% FeS2 and 22% gangue is burned at the rate of 1000 kg/hr. Analysis of the
cinder shows 7.22% S as unburned FeS2 and SO3 absorbed by Fe2O3 and 27.9% gangue. Air
supplied is 70% in excess based on conversion of FeS2 to SO2. The ratio of SO2 to SO3 in the
burner gas is 3.48:1.
21.The % excess air (FeS2 to SO3) is about
(A) 10
(B) 20
(C) 25
(D) 56
22.The % of the FeS2 charged lost in the cinder is about
(A) 12
(C) 15
(B) 20
(D) 8
23.The % of SO2 in the burner gas is about
(A) 5.2
(B) 2.7
(C) 4.5
(D) 6.3
24. When a portion of the recycle stream is withdrawn and steady state condition is maintained.
The removal of impurities along with recycle stream partly under this situation is called
(A) recycling operation.
(C) bypass operation.
(B) weeping operation.
(D) purging operation
25.Carbon tetrachloride is produced by reacting carbon disulfide with a n excess amount of
chlorine gas. The following reaction occurs:
CS 2 + 3Cl 2 → CCl 4 + S 2Cl 2
Component
CS2
Cl2
CCl4
S2Cl2
MW
76
71
154
135
If 100 lb of Cl2 is reacted, the amount (lb) of carbon tetrachloride produced is most nearly:
(A) 63.4
(C) 138
(B) 72.3
(D) 217
SITUATION FOR PROBLEMS 26-30:
The combustion product from a hydrocarbon fuel has the following Orsat analysis: CO2 = 13%,
CO = 0.5%, O2 = 3.5%, N2 = 83%.
26. How many mols of water vapor are formed per mol of fuel burned?
(A) 9.82
(C) 11.1
(B) 10.6
(D) 12.2
27. What is the molecular formula of the fuel?
(A) C10.6H20.2
(B) C11.2H22.4
(C) C13.5H21.3
(D) C14.2H26.4
28. What is the air-fuel ratio on a mass basis?
(A) 10 kg air/kg fuel
(B) 12 kg air/kg fuel
(C) 15 kg air/kg fuel
(D) 17 kg air/kg fuel
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
29. What is the percent excess air supplied?
(A) 17%
(B) 19%
FEBRUARY 10, 17, 24, 2024
(C) 22%
(D) 26%
30. If the total pressure is 1 atm, what is the dew point of the combustion product?
(A) 112 0F
(C) 131 0F
0
(B) 122 F
(D) 140 0F
31. 1000 pounds per minute of a gas (average molecular weight= 30.24) is being sent to an
absorption column. What is the molar flow rate of the gas in kmol/h?
(A) 780
(C) 900
(B) 987
(D) 678
32. Sulphur trioxide gas is obtained by the combustion of iron pyrites (FeS2) according to the
following reaction: 4FeS2 + 1502 → 2Fe203 + 8S03. How many kilograms of oxygen are
consumed in the production of 50 kg of S03?
(A) 37.48
(C) 41.88
(B) 45.43
(D) 49.32
33. Iron reacts with steam according to the following reaction: 3Fe + 4H20 → Fe304 + 4H2. How
many kilograms of iron are required to produce 100 kg of hydrogen?
(A) 2233
(C) 1677
(B) 1889
(D) 2078
34. The final purification stage in the preparation of a pharmaceutical product A from natural
sources requires centrifuging and continuous filtration as shown in the figure below.
Determine the flow rate of the recycle stream in kg/h.
(A) 23
(B) 26
(C) 17
(D) 19
35. A body weighs 1.0 kg in air, 0.90 kg in water and 0.82 kg in a liquid. What is the specific
gravity of the liquid?
(A) 1.08
(C) 1.45
(B) 1.8
(D) 1.6
36. 10 kg of liquid A of specific gravity 1.17 is mixed with 5 kg of liquid B of specific gravity
0.83. Assuming that there is no volume change on mixing, what is the density (kg/m3) of the
mixture? (Take the density of water = 1000 kg/m3.)
(A) 1029
(C) 1031
(B) 1012
(D) 1019
37. What is the specific gravity on the Baume scale for a 100°Tw solution?
(A) 43.7
(C) 39.8
(B) 50.2
(D) 48.3
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
38. Blast furnace gas constitutes mainly of
(A) CH4 & C02
(B) N2 & CO
FEBRUARY 10, 17, 24, 2024
(C) N2 & H2
(D) N2 & CH4
39. Liquid fuel for an automobile engine has the following composition (wt%):
Element
Wt%
Atomic Weight
C
88.7
12.00
H
9.3
1.01
O
2.0
16.00
The theoretical amount of oxygen (lb moles) per 100 lb of fuel is most nearly:
(A) 7.4
(C) 12.0
(B) 9.6
(D) 45.9
40. A mixture of air and water vapor weighs 75 kg. If the water vapor weighs 1.3 kg, the
humidity of air is close to
(A) 0.0173
(C) 0.0176
(B) 0.0188
(D) 0.1610
41. How many pounds of calcium fluoride rock is needed to produce 3000 lbs of a 60% HF per
day if the yield is 90% and the rock contains 95% CaF2?
(A) 4105.2
(C) 3510.0
(B) 3694.7
(D) 3900.0
42. The partial pressure of water vapor is 50 mmHg in a mixture of air and water vapor at 110
0
F and 1 atm. The percentage relative humidity of the mixture is closest to
(A) 85.66
(C) 75.92
(B) 95.72
(D) 65.86
43. At certain temperature and 1 atm total pressure, the partial pressure of water in air is 25
mmHg. What is the humidity of the air?
(A) 0.1120
(C) 0.0053
(B) 0.0211
(D) 0.2111
SITUATION FOR PROBLEMS 44-49:
Methane reacts with oxygen to form carbon dioxide and water. 200 lbmol/h of a feed consisting
of 25% methane, 65% oxygen, and 10% carbon dioxide are fed to a reactor that achieves a 90%
conversion of the limiting reactant.
44. What is the percent excess reactant?
(A) 15%
(B) 23%
(C) 30%
(D) 36%
45. What is the molar flow rate of methane in the product stream?
(A) 3 lbmol/h
(C) 7 lbmol/h
(B) 5 lbmol/h
(D) 9 lbmol/h
46. What is the molar flow rate of the product stream?
(A) 100 lbmol/h
(C) 300 lbmol/h
(B) 200 lbmol/h
(D) 400 lbmol/h
47. What is the mol fraction of carbon dioxide in the product stream?
(A) 0.20
(C) 0.28
(B) 0.25
(D) 0.33
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
48. If the total pressure is 14.7 psia, what is the partial pressure of oxygen?
(A) 2.9 psia
(C) 4.2 psia
(B) 3.6 psia
(D) 4.9 psia
49. If the temperature of the product gas is 360 0F, what is the volume flow rate of the product
gas?
(A) 1600 ft3/min
(C) 2000 ft3/min
(B) 1800 ft3/min
(D) 2300 ft3/min
SITUATION FOR PROBLEMS 50-51:
A wet solid containing 70% water is mixed with a recycled dry solid to reduce the water content
to 50% before being admitted into the granulator. The solid leaving the granulator is fed to a
drier where it is brought into contact with dry air initially containing 0.25% water by weight. In
the drier, the air picks up moisture and leaves with a moisture content of 5%. The solids leaving
the drier contain 20% water. A portion of this solid is recycled. For 1000 kg/h of wet solid sent
to the granulator as fresh feed,
50. The amount (kg/h) of solid recycled is close to
(A) 569
(C) 723
(B) 667
(D) 594
51. The circulation rate (kg/h) of air in the drier on a dry basis is close to
(A) 11000
(C) 11250
(B) 12500
(D) 12100
52. A mixture of pure benzene and toluene is sampled and found to have a boiling point of 84 0C
at 760 mmHg. The vapor pressure of pure benzene at this temperature is 852 mmHg and of
pure toluene 333 mmHg. Calculate the weight percent of benzene in this mixture.
(A) 82.27
(C) 68.71
(B) 79.73
(D) 86.17
SITUATION FOR PROBLEMS 53-55:
A 10 N aqueous solution of sulfuric acid (30 0Tw) is made to react with a 55% aqueous solution
of sodium hydroxide (640Be) to form 1350 g of sodium sulfate per liter of sodium hydroxide
solution. The volume ratio of the acid to the base solution is 2:1.
53. The limiting reactant in the reaction is
(A) NaOH
(B) H2SO4
(C) Na2SO4
(D) H2O
54. The degree of completion of the above reaction is
(A) 85%
(C) 95%
(B) 92%
(D) 72%
55. A mixture of 4 moles of benzene and 6 moles of toluene will boil at approximately
(A) 95 0C
(C) 100 0C
0
(B) 215 F
(D) 220 0F
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
56. Liquid fuel for an automobile engine has the following composition (wt%):
Element
Wt%
Atomic Weight
C
88.7
12.00
H
9.3
1.01
O
2.0
16.00
The gas composition (mole%, dry basis) leaving the engine is:
Component
Mole% (Dry Basis)
CO2
14.00
CO
1.50
H2
1.00
N2
80.96
O2
2.54
Molecular Weight
44.01
28.01
2.02
28.02
32.00
The fuel (lb) supplied to the engine per 100 lb moles of dry exhaust gas is most nearly:
(A) 17.5
(C) 189
(B) 200
(D) 210
57. A plant makes very high-grade lime by calcination of pure CaCO3 in rotary kilns. In one kiln,
the reaction goes to 95% completion. The yield in terms of lb of CO2 produced per lb of
calcium carbonate is
(A) 0.242
(C) 0.324
(B) 0.418
(D) 0.366
58. Aluminum sulfate is manufactured by treating crushed bauxite ore with sulfuric acid. The ore
contains 55.4% Al2O3. Sulfuric acid is 77.7% H2SO4. In one batch, 2160 lb of bauxite ore
was treated with 5020 lb of sulfuric acid to obtain a final solution containing 3600 lb of
aluminum sulfate. Percent conversion of Al2O3 is near to
(A) 84.7
(C) 89.6
(B) 67.4
(D) 96.2
59. An adiabatic humidifier operates at atmospheric pressure under such conditions that the air
leaving the unit is saturated at the adiabatic saturation temperature. If the air enters the
humidifier at 80 0F with a humidity of 0.005 lb of water vapor per lb of dry air, what will be
the humidity of the air leaving the unit?
(A) 0.050
(C) 0.110
(B) 0.125
(D) 0.010
60. Air at 150 0F and a humidity of 0.0012 kg water per kg dry air at 1 atm enters a drier. If the
mass rate of dry air is 50 kg per hour, then the volumetric flowrate [ft3/hr] of air is
approximately equal to
(A) 1693.61
(C) 936.00
(B) 6319.10
(D) 3190.61
61. A compressor delivers air at a total pressure of 40 psia and a temperature of 90 0F. If this air
is saturated with water vapor, what is the humidity of the air? Assume Dalton’s law applies
to this mixture.
(A) 0.1010
(C) 0.1521
(B) 0.0525
(D) 0.0111
62. Air at 760 mmHg pressure, having a wet bulb temperature of 50 0F and a dry bulb
temperature of 70 0F, enters a humidifier. If the air leaving the unit has a humidity of 0.007
kg of water vapor per kg of dry air, how many kg of water vapor are evaporated into the air
for every 100 kg of dry air entering the unit?
(A) 0.2
(C) 0.4
(B) 0.78
(D) 0.65
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
SITUATION FOR PROBLEMS 63-65:
For the reaction A→ B, the process flow diagram is shown in Figure below. The fresh feed of A
contains 0.5% of inerts by volume. 60% conversion of A per pass is obtained. The concentration
of inerts going into the reactor at (1) must be held at 2% by volume. All streams are ideal gases
and the process is at steady state.
63. How many moles need to be recycled per mole of total feed to the reactor at (1)?
(A) 0.56
(C) 0.34
(B) 0.23
(D) 0.45
64. How many moles need to be purged?
(A) 0.18
(B) 0.45
(C) 0.32
(D) 0.07
65. What is the overall percentage conversion of A?
(A) 90.2
(C) 93.1
(B) 88.9
(D) 82.9
SITUATION FOR PROBLEMS 66-68:
Formaldehyde is produced by oxidizing methane using air. A side reaction is the combustion of
methane to form carbon dioxide. The reactions are as follows.
CH4 + O2 → HCHO(g) + H2O(g)
CH4(g) + 2O2 → CO2 + 2H2O(g)
100 mol/h of methane at 25 0C is fed to a reactor, and there is a 30% (mol%) conversion to
formaldehyde. 20% of the remaining methane participates in the side reaction to form carbon
dioxide. Air at 100 0C is fed at the rate of 500 mol/h.
66. What is the molar flow rate of nitrogen in the feed stream?
(A) 100 mol/h
(C) 300 mol/h
(B) 200 mol/h
(D) 400 mol/h
67. What is the molar flow rate of methane in the product stream?
(A) 44 mol/h
(C) 62 mol/h
(B) 56 mol/h
(D) 70 mol/h
68. What is the molar flow rate of water vapor in the product stream?
(A) 35 mol/h
(C) 49 mol/h
(B) 41 mol/h
(D) 58 mol/h
SITUATION FOR PROBLEMS 69-71:
A liquid mixture containing benzene and toluene is in equilibrium with the vapor phase at a
temperature of 70 0F. Use the following Antoine’s Equation [log P = A – B/(C + t)] constants for
C6H6: A=6.89272, B=1203.531, C=219.888. For C6H5CH3: A=6.95805, B=1346.773,
C=219.693. The composition of the liquid is 40% benzene by mass.
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
69. What is the mole fraction of benzene in the liquid phase?
(A) 0.38
(C) 0.51
(B) 0.44
(D) 0.62
70. What is the total pressure in the vapor phase?
(A) 0.061 atm
(B) 0.072 atm
(C) 0.083 atm
(D) 0.094 atm
71. What is the mole fraction of benzene in the vapor phase?
(A) 0.51
(C) 0.65
(B) 0.58
(D) 0.73
SITUATION FOR PROBLEMS 72-74:
Air at 320 K saturated with water vapor is dehumidified by cooling to 285 K and by
condensation of water vapor. Air leaving the dehumidifier saturated at 285 K is mixed with a
part of the original air which has bypassed the dehumidifier. The resulting air stream is reheated
to 320 K. It is desired that the final air contains water vapor not more than 0.03 kg per kg of dry
air.
72. The dry air bypassed (kg) per each kg of dry air sent through the dehumidifier is about
(A) 1.0
(C) 0.5
(B) 0.7
(D) 0.3
73. The water vapor condensed in the dehumidifier (kg) per 100 m3 of air sent through it is close
to
(A) 4.7
(C) 5.2
(B) 7.0
(D) 6.3
74. The volume (m3) of final air obtained per 100 m3 of air passed through the dehumidifier is
close to
(A) 154
(C) 123
(B) 141
(D) 134
75. A mixture of air and water vapor contains 5 lb of water vapor for every 200 lb of dry air. If
the temperature of the mixture is 120 0F and the total pressure is 760 mmHg, which of the
following statements is incorrect?
(A) The actual pressure of water in the air is 29.4 mmHg
(B) The dew point of the mixture is 28.6 0C
(C) The percentage humidity of the air is 40.5
(D) The percentage relative humidity of the air is 33.6
76. The partial pressure of water vapor is 50 mmHg in a mixture of air and water vapor at 110 0F
and 1 atm pressure. How much BtU of heat energy must be added to 25 lb of this mixture to
raise the temperature to 125 0F?
(A) 34.9
(C) 58.9
(B) 43.9
(D) 93.4
SITUATION FOR PROBLEMS 77-80:
One Hundred kgmoles per hour of dry air mixture containing 50% SO3 is fed to the bottom of a
countercurrent absorption tower to concentrate 5MT/hr dilute acid solution (5% H2SO4) flowing
down from the top of the tower, the exit gas contains 5% of the original SO3 at 101.325 kPa total
pressure and 30 kPa water vapor pressure.
77. The amount (kgmol/hr) of water evaporated from the entering liquid is about
(A) 24
(C) 22
(B) 18
(D) 20
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
78. The amount (kgmol/hr) of SO3 absorbed and converted to H2SO4 is
(A) 57.4
(C) 75.4
(B) 44.7
(D) 47.5
79. The total (kgmol/hr) amount of H20 as H2SO4 in weak liquor is about
(A) 266
(C) 213
(B) 314
(D) 411
80. The percentage of H2SO4 in the exit liquid is about
(A) 53.88
(C) 35.88
(B) 83.85
(D) 58.38
SITUATION FOR PROBLEMS 81-84:
Coal-fired in a furnace analyzes 16.6% VCM, 16% ash, 61.4% FC, 6% M, 1.2%N, and 1.8%S
with a calorific value of 26.75 MJ/kg. Analysis of the Residue shows 44% ash, 8% VCM, 34%
FC, and 14% H2O. Partial Orsat analysis of the stack gas shows 10.77% CO2, 1.62% CO and
0.81% H2. Air supplied is at 27oC, 765 torrs with 80% RH.
81. The %VCM lost in the Residue is about
(A) 19.92
(B) 17.52
(C) 21.09
(D) 14.33
82. The % excess air is about
(A) 4.8
(B) 15.8
(C) 20.4
(D) 12.3
83. The amount (m3) of air supplied per kg of coal is about
(A) 9.04
(C) 12.93
(B) 5.99
(D) 3.87
84. The % O2 in the dry stack gas is about
(A) 0.44
(B) 5.67
(C) 3.09
(D) 8.17
SITUATION FOR PROBLEMS 85-87:
In the burning of pyrite containing 92% FeS2 and 8% gangue, 13% of the FeS2 charged is lost in
the cinder. A partial analysis of the cinder also shows 5.31% SO3. The orsat analysis of the
burner gases shows 6.75% SO2, 6.88% O2 and 86.37% N2. Air supplied is at 23oC , 743 mm Hg
and 88% RH.
85. The % excess air (FeS2 to SO2) is about
(A) 24
(B) 47
(C) 40
(D) 16
86. The m3 air/kg pyrite is about
(A) 3.58
(B) 1.43
(C) 0.89
(D) 5.87
87. The m3 burner gas (205oC, 750 mm Hg)/kg pyrite is about
(A) 3.76
(C) 7.66
(B) 5.95
(D) 1.98
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
SITUATION FOR PROBLEMS 88-89:
A plant is burning limestone which analyzes 52% CaO, 41% CO2, and 7% inerts using coke that
analyzes 90% C and 10% ash. The lime product obtained contains 3% CO2 and 1% unburned C.
The top gas shows 24.1% CO2, 1% CO, and 74.9% N2.
88. The kg limestone/kg coke is about
(A) 1.12
(B) 1.91
(C) 0.70
(D) 0.09
89. The Lime-Fuel Ratio is about
(A) 1.18
(B) 2.55
(C) 2.99
(D) 0.54
SITUATION FOR PROBLEMS 90-97:
A continuous dryer is designed to produce 20,000 kg of product containing 5% water in a 24 h
period. The product enters the dryer with 35% water. The air used for drying has an inlet
temperature of 20oC and a relative humidity of 45%, and it is preheated to 55oC before it is fed to
the dyer. The air leaves the dryer fully saturated at 32oC.
90. What is the mass flow rate of dry (0% moisture) solid?
(A) 792 kg/h
(C) 896 kg/h
(B) 833 kg/h
(D) 948 kg/h
91. What is the feed rate of the wet solid (35% moisture) to the dryer?
(A) 1055 kg/h
(C) 1281 kg/h
(B) 1218 kg/h
(D) 1346 kg/h
92. What is the rate of removal of water from the wet solid in the dryer?
(A) 384 kg/h
(C) 483 kg/h
(B) 427 kg/h
(D) 548 kg/h
93. What is the moisture content of the air entering the dryer?
(A) 0.0048 kg water/kg dry air
(C) 0.0058 kg water/kg dry air
(B) 0.0052 kg water/kg dry air
(D) 0.0065 kg water/kg dry air
94.What is the relative humidity of the air entering the dryer?
(A) 5%
(C) 15%
(B) 10%
(D) 20%
95. What is the moisture content of the air leaving the dryer?
(A) 0.016 kg water/kg dry air
(C) 0.031 kg water/kg dry air
(B) 0.021 kg water/kg dry air
(D) 0.050 kg water/kg dry air
96. What volume flow rate of air must to be fed to the pre-heater?
(A) 1.6 m3/s
(C) 3.1 m3/s
(B) 2.4 m3/s
(D) 3.7 m3/s
97. What is the rate at which heat is added in the pre-heater?
(A) 146 kW
(C) 161 kW
(B) 143 kW
(D) 172 kW
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
FEBRUARY 10, 17, 24, 2024
SITUATION FOR PROBLEMS 98-99:
A natural gas analyzes 90% methane and 10% nitrogen. It is burned under a boiler and the
carbon dioxide is scrubbed out from the gases for the production of dry ice. The analysis of the
gas leaving the scrubber shows 1.1% carbon monoxide, 5% oxygen, and 93.9% nitrogen.
98. The percent carbon dioxide absorbed in the scrubber is
(A) 88.8
(C) 76.4
(B) 95.2
(D) 85.7
99. The percent excess air used is
(A) 20
(B) 22.5
(C) 25.4
(D) 28.6
100.The cinder from the combustion of iron pyrites containing 80% wt FeS2 and 20% wt gangue
carries 1.2% S as SO3. How many pounds of SO3 are lost in the cinder per 100 lb of pyrites
charged?
(A) 3.24
(C) 2.65
(B) 1.88
(D) 0.98
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA