CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
SET 1 - SAMPLE QUESTIONS
CHE CALCULATIONS
Compiled by: Engr. Albert D.C. Evangelista
MULTIPLE CHOICES:
1. Which of the following statements is incorrect?
(A) Measurement of the amount of dry gas collected over water from volume of moist gas is
based on the Dalton’s law of partial pressures.
(B) The pressure of 'V' liters of a dry gas is increased from 1 to 2 kgf/cm2 at a constant
temperature. The new volume will become 2V.
(C) Recycling in a chemical process facilitates heat conservation.
(D) The vapor pressure of a solution (made by dissolving a solute in a solvent) is greater
than that of the pure solvent.
2. Which of the following chart is related to Antoine’s equation?
(A) Mollier’s
(C) Cox
(B) Enthalpy-Concentration
(D) Ostwald
3.
It is used to indicate the strength of sugar solution.
(A) Baume scale
(C) Twaddell scale
(B) API scale
(D) Brix scale
4. Which of the following statements is incorrect?
(A) Validity of the relationship, inputs = outputs, holds good for the system at steady state
without chemical reaction & losses.
(B) Addition of a non-volatile solute to a solvent produces a vapor pressure increase in its
solvent.
(C) The ratio of existing moles of vapor per mole of vapor free gas to the moles of vapor
that would be present per mole of vapor free gas, if the mixture were saturated at the
existing temperature & pressure, is termed as the percentage saturation.
(D) Kirchoff’s equation gives the effect of temperature on heat of reaction.
5. The number of replaceable hydrogen atoms in a molecule of acid is known as the ________
of the acid
(A) conductivity
(C) basicity
(B) activity
(D) acidity
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
7. Which of the following statements is incorrect?
(A) Number of gm moles of solute dissolved in one liter of a solution is called its molarity.
(B) Recycling in a chemical process facilitates enrichment of product.
(C) Recycle stream/fresh feed stream defines the recycle ratio in a chemical process.
(D) Percentage saturation of a vapor bearing gas is always greater than the relative
saturation.
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
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
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. Which of the following statements is incorrect?
(A) 1 gm mole of methane (CH4) contains 4 gm atoms of hydrogen.
(B) Number of gram equivalent of solute dissolved in one liter of solution is called its
normality.
(C) Heat of reaction is not a function of the pressure.
(D) Recycling in a chemical process facilitates increased yield.
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
13. Which of the following statements is incorrect?
(A) Kopp's rule is concerned with the calculation of heat capacity
(B) For a given mass of a gas at constant temperature, if the volume 'V' becomes three
times, then the pressure 'P' will become 9P2.
(C) In a chemical process, the recycle stream is purged for limiting the inerts.
(D) Raoult's law states that 'the equilibrium vapor pressure that is exerted by a component in
a solution is proportional to the mole fraction of that component'. This generalization is
based on the assumption that the component molecules are non-polar and no chemical
combination or molecular association between unlike molecules takes place in the
formation of the solution.
14. It states that for a fixed quantity of a gas, the volume is inversely proportional to pressure at
constant temperature.
(A) Charles' law
(C) Boyle's law
(B) Avogadro's principle
(D) Gay-Lussac’s Law
15. It is obtained by combining Boyle's law and Charle's law.
(A) Ideal Gas Law
(C) Van der Waals equation
(B) Boycha Law
(D) Avogadro's principle
16. Which of the following statements is incorrect?
(A) Number of gm moles of solute dissolved in 1 kg of solvent is called its molality.
(B) Kinetic theory of gases stipulates that, the absolute temperature is a measure of the
kinetic energy of molecules.
(C) The heat capacity of a solid compound is calculated from the atomic heat capacities of
its constituent elements with the help of the Kopp's rule.
(D) For water evaporating into unsaturated air under adiabatic conditions and at constant
pressure, the dry bulb temperature remains constant throughout the period of
vaporization.
17. It states that the total pressure of a mixture of gases is equal to the sum of the partial
pressures of the individual components.
(A) Amagat's Law
(C) Dalton's Law
(B) Henry’s Law
(D) Avogadro's principle
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
18. It states that the total volume of a mixture of gases at a given temperature and pressure is
equal to the sum of the pure component volumes of the constituents at the same temperature
and pressure.
(A) Amagat's Law
(C) Dalton's Law
(B) Henry’s Law
(D) Avogadro's principle
19. This equation express the compressibility factor Z (= PV/RT) as functions of pressure or
volume.
(A) Peng-Robinson equation
(C) Redlich-Kwong-Soave equation
(B) Van der Waals equation
(D) Virial equations
20. Which of the following statements is incorrect?
(A) The temperature of a gas in a closed container is 27°C. If the temperature of the gas is
increased to 300°C, then the pressure exerted is doubled.
(B) Cv for monoatomic gases is equal to 1.5 R
(C) Boiling point of a solution as compared to that of the corresponding solvent is more.
(D) Pressure has the least (almost negligible) effect on the solubility of a solute in a solvent.
21. It measures the deviation of a gas from ideal behavior. It is defined as Z = PV/RT.
(A) Fugacity coefficient
(C) critical point
(B) Activity coefficient
(D) compressibility factor
22. Which of the following statements is incorrect?
(A) ''The total volume occupied by a gaseous mixture is equal to the sum of the pure
component volumes". This is the Amagat’s law.
(B) Heat of reaction is not a function of the temperature.
(C) Specific gravity on API scale is given by the relation 0API = (141.5/G) - 131.5.
(D) Raoult's law states that 'the equilibrium vapor pressure that is exerted by a component in
a solution is proportional to the mole fraction of that component'. This generalization is
based on the assumption that the attractive forces between like and unlike molecules are
approximately equal.
23. It states that the vapor pressure of a component in a solution (or the equilibrium partial
pressure of the component) is directly proportional to its concentration.
(A) Henry’s Law
(C) Dalton’s Law
(B) Raoult's Law
(D) Amagat’s Law
24. It states that the partial pressure of a component over a liquid solution is directly
proportional to the concentration of the component in the liquid.
(A) Henry’s Law
(C) Dalton’s Law
(B) Raoult's Law
(D) Amagat’s Law
25. Which of the following statements is incorrect?
(A) Equal masses of CH4 and H2 are mixed in an empty container. The partial pressure of
hydrogen in this container expressed as the fraction of total pressure is8/9.
(B) With rise in temperature, the heat capacity of a substance decreases.
(C) A 'limiting reactant' is the one, which decides the conversion in the chemical reaction.
(D) ''The equilibrium value of the mole fraction of the gas dissolved in a liquid is directly
proportional to the partial pressure of that gas above the liquid surface". This statement
pertaining to the solubility of gases in liquid is the Henry's law.
26. The temperature at which the first drop of condensate is formed when a vapor is cooled at
constant pressure is the
(A) triple point
(C) dew point
(B) sublimation point
(D) boiling point
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
27. It is the ratio of the actual partial pressure exerted by the vapor to its vapor pressure at the
same temperature, which is expressed as a percentage.
(A) percentage recovery
(C) percentage humidity
(B) percentage moisture
(D) percentage relative humidity
28. Which of the following statements is incorrect?
(A) For an ideal gas, the compressibility factor is 100 at all temperature.
(B) A bypass stream in a chemical process is useful, because it facilitates better control of
the process.
(C) 0Be = (140/G) -130 defines the Baume gravity scale for liquids lighter than water.
(D) Raoult's law states that 'the equilibrium vapor pressure that is exerted by a component in
a solution is proportional to the mole fraction of that component'. This generalization is
based on the assumption that the sizes of the component molecules are approximately
equal.
29. The difference between the dry-bulb and wet-bulb temperature is known as the
_____________ and is a measure of the humidity of the air stream.
(A) Range
(C) wet-bulb depression
(B) approach
(D) dry-bulb depression
30. The ratio of heat-transfer coefficient to the mass transfer coefficient of air film is also known
as
(A) Saturation ratio
(C) limiting ratio
(B) psychrometric ratio
(D) Lewis relation
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. What is the equivalent weight of CaC03?
(A) 100.08
(B) 50.4
(C) 33.33
(D) 66.7
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 density of water = 1000 kg/m3.)
(A) 1029
(C) 1031
(B) 1012
(D) 1019
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
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
38. 250 cubic meters of 30 °API gas oil is blended with 1000 cubic meters of 15 °API fuel oil.
What is the density of the resultant mixture in kg/m3? The density of water at 288.5 K = 999
kg/m3. Assume no volume change on mixing.
(A) 968
(C) 989
(B) 935
(D) 947
39. A wet stock of ammonium sulphate containing 25% water on dry basis is sent to a drier. The
material leaving the dryer contains 2.5% moisture on dry basis. The percentage of water
removed in the drying operation is
(A) 90
(C) 88
(B) 93
(D) 94
40. A solution of carbon tetrachloride and carbon disulfide containing 50% by weight of each is
continuously distilled at a rate of 4,000 kg/h. In terms of kmol/h, the rate is
(A) 27.39
(C) 32.79
(B) 29.37
(D) 39.27
41. On mixing 56 gm of CaO with 63 gm of HN03, the amount (g) of Ca(N03\ formed is
(A) 8.2
(C) 41
(B) 164
(D) 82
42. The solubility of sodium chloride in water at 290 K is 35.8 kg/100 kg of water. The mass
percent of NaCl is
(A) 25.11
(C) 24.76
(B) 26.36
(D) 23.54
43. Pure water and alcohol are mixed to get a 60% (weight) alcohol solution. The densities
(kg/m3) of water, alcohol and the solution may be taken to be 998, 798 and 895 respectively
at 293 K. Calculate the molarity.
(A) 13.76
(C) 12.65
(B) 10.22
(D) 11.67
SITUATION FOR PROBLEMS 44-46:
Carbon monoxide combines with chlorine in the presence of a suitable catalyst to form phosgene
according to the following reaction: CO(g) + Cl2(g) → COCl2(g). After reaction, the products
contained 12 moles of phosgene, 3 moles of chlorine and 8 moles of carbon monoxide.
Assuming that the original reactant mixture is free of phosgene.
44. The percent excess reactant used is close to
(A) 27.15
(B) 30.09
(C) 33.33
(D) 24.32
45. The percent conversion of the limiting reactant is close to
(A) 70
(C) 85
(B) 80
(D) 75
46. The moles of the total product per mole of the reactant mixture fed to the reactor is close to
(A) 0.66
(C) 0.83
(B) 0.76
(D) 0.71
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
SITUATION FOR PROBLEMS 47-49:
In the vapor-phase hydration of ethylene to ethanol, diethyl ether is obtained as a by-product.
C2H4 + H20 → C2H5OH
2C2H4 + H20 → (C2H5)20
A 100 mol feed mixture consisting of 60% ethylene, 3% inerts and 37% water is sent to the
reactor. The products analyzed 53.89% ethylene, 14.37% ethanol, 1.80% ether, 26.35% water,
and 3.59% inerts.
47. The conversion of ethylene is close to
(A) 27
(B) 30
(C) 25
(D) 32
48. The yield (%) of ethanol based on ethylene is close to
(A) 76
(C) 67
(B) 83
(D) 80
49. The yield (%) of ether based on ethylene is close to
(A) 27
(C) 24
(B) 20
(D) 17
50. An automobile tire is inflated to a pressure of 195 kPa at 273 K. If the pressure inside the
tire is not to exceed 250 kPa, what is the maximum temperature (K) to which the tire may be
heated?
(A) 333
(C) 367
(B) 350
(D) 317
51. Carbon dioxide is contained in a 250 L cylinder at a temperature of 300 K. The gas from the
cylinder is allowed to enter an evacuated chamber of capacity 750 L by opening a valve. The
flow of gas into the chamber stops when the pressures inside the chamber and the cylinder
equal 100 kPa. The temperature of the gas is uniform throughout and it is equal to 310 K.
What was the original pressure (kPa) inside the cylinder?
(A) 378.2
(C) 367.8
(B) 387.1
(D) 397.8
52. An analysis of the vent gases from the chlorinator in a plant for making chlorinated rubber
showed 70% by volume HCl, 20% by volume Cl2 and the rest CC14. The average molecular
weight of the gas is
(A) 46.77
(C) 49.00
(B) 55.08
(D) 52.98
53. Natural gas is piped from the well at 300 K and 400 kPa. The gas is found to contain 93.0%
methane, 4.5% ethane and the rest nitrogen. The pure-component volume (m3) of ethane in
10 m3 of the gas is
(A) 0.45
(C) 0.23
(B) 1.55
(D) 1.09
54. 100 m3/h of an ammonia-air mixture containing 20% ammonia by volume is admitted to an
absorption column at 120 kPa and 300 K in order to recover ammonia by absorbing in water.
90 percent of ammonia in the entering gas is absorbed and the gas leaves the column at 100
kPa and 280 K. What is the volume (m3) of gas leaving in one hour?
(A) 76.33
(C) 67.33
(B) 82.84
(D) 91.84
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
SITUATION FOR PROBLEMS 55-56:
100 m3 of Air is to be dehumidified by condensing the water vapor present in it by cooling at
constant pressure. 100 m3 of air at 100 kPa and 300 K contains water vapour which exerts a
partial pressure of 4 kPa. Keeping the pressure constant, this air is cooled to 275 K and the
condensed water is removed. The partial pressure of water in the air after cooling is found to be
1.8 kPa.
55. The volume of air after dehumidification in m3 is close to
(A) 98.32
(C) 80.32
(B) 89.61
(D) 74.22
56. The mass of water removed in kg is close to
(A) 1.62
(B) 2.12
(C) 1.24
(D) 0.89
57. Ammonia is made by the reaction between hydrogen and nitrogen according to the following
reaction: N2 + 3H2 → 2NH3. What is the volume (m3) of hydrogen at 5 bar and 290 K
required which is stoichiometrically equivalent to 100 m3 of nitrogen at 20 bar and 350 K?
(A) 1212
(C) 994
(B) 1087
(D) 976
58. Carbon dioxide dissociates into carbon monoxide and oxygen at 1 bar and 3500 K according
to the reaction: C02 → CO + 0.502. 25 L of C02 at 1 bar and 300 K is heated to 3500 K at
constant pressure. All gases behave ideally. If the final volume is found to be 0.35 m3, what
fraction of C02 is dissociated?
(A) 0.54
(C) 0.32
(B) 0.21
(D) 0.40
59.A mixture of noble gases (helium, krypton, argon, and xenon) is at a total pressure of 200 kPa
and a temperature of 400 K. If the mixture has equal mole fractions of each of the gases, the
mass density [kg/m3] of the mixture is
(A) 9.3
(C) 6.3
(B) 3.9
(D) 3.6
60.A sample of liquefied natural gas, LNG, from Alaska has the following molar composition:
93.5% CH4, 4.6% C2H6, 1.2% C3H8, and 0.7% CO2. The LNG is heated to 300 K and 140
kPa, and vaporizes completely. The estimated density [kg/m3] of the gas mixture under this
conditions is
(A) 0.967
(C) 0.796
(B) 0.697
(D) 0.267
61.A combustor generates 719 lb moles/hr of gases at 1,800oF and 1 atm. The actual flow rate
(ft3/min) at which exhaust gas leaves the combustor is most nearly:
(A) 4.3x103
(C) 2.6x105
4
(B) 2.0x10
(D) 1.2x106
62. The table below gives the characteristics of a gas stream flowing at a rate of 100 lb moles/hr.
Component
MW
N2
28
SO2
64
The N2 flow rate (lb/hr) is most nearly:
(A) 2,800
(B) 3,500
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
Mol%
80
20
(C) 2,250
(D) 80
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
63. What is the density of helium at 600 0F (300 0C) and one standard atmosphere?
(A) 0.0076 lbm/ft3 (0.12 kg/m3)
(C) 0.0061 lbm/ft3 (0.098 kg/m3)
3
3
(B) 0.0095 lbm/ft (0.15 kg/m )
(D) 0.0052 lbm/ft3 (0.085 kg/m3)
64. What is the pressure inside a 1 m3 container containing 104 g-moles of nitrogen gas at a
temperature of -122 0C? The critical temperature and pressure of nitrogen are 126K and 34
bar, respectively.
(A) 150 bar
(C) 73 bar
(B) 126 bar
(D) 34 bar
65. An ideal gas is isentropically compressed from 50 psig to 250 psig. The Inlet temperature is
200 0F and outlet temperature is 701.50F. What gas is compressed? Use R = 1.98
BtU/(lbmole.0R)
(A) Methane
(C) Butane
(B) Helium
(D) Air
66. The pressure (bar) developed by one kmol gaseous ammonia contained in a vessel of 0.6 m 3
capacity at a constant temperature of 473 K by using the van der Waals equation given that
a= 0.4233 N m4/mol2; b = 3.73 x 10-5 m3/mol is about
(A) 87
(C) 74
(B) 58
(D) 66
67. Assume that gaseous ammonia follows the Redlich-Kwong equation of state. Calculate the
pressure developed by one mole of NH3 contained in a vessel of volume 0.6 x 10-3 m3 at 473
K given that the critical pressure and temperature are 112.8 bar and 405.5 K.
(A) 87
(C) 74
(B) 58
(D) 66
68. Calculate the vapor pressure (kPa) of water at 363 K if the vapor pressure at 373 K is 101.3
kPa. The mean heat of vaporization in this temperature range is 2275 kJ/kg.
(A) 73.8
(C) 70.4
(B) 67.3
(D) 72.6
69. A liquid mixture containing 25% A, 30% B and the rest C is in equilibrium with the vapor
which contains 50% B. All percentages are on a mole basis. The equilibrium pressure and
temperature are 200 kPa and 350 K. At 350 K the vapor pressure of C is 50 kPa. What is the
percentage of A in the vapor?
(A) 43.44
(C) 34.21
(B) 38.75
(D) 49.21
70. A liquid mixture containing 65 mol % benzene and 35 mol % toluene is subjected to flash
vaporization at 363 K and 101.3 kPa. The vapor pressure of benzene at this temperature is
136.09 kPa and the vapor pressure of toluene is 54.21 kPa. Flash vaporization is essentially
an equilibrium stage operation. Calculate the mole percent of the feed that is vaporized.
(A) 43.4%
(C) 54.2%
(B) 37.9%
(D) 47.2%
71. An aqueous solution of acetaldehyde contains 2% acetaldehyde by weight. The partial
pressure of acetaldehyde over the solution is found to be 41.4 kPa at 367 K. What will be the
partial pressure (kPa) over a 0.1 molal solution at the same temperature?
(A) 12
(C) 7
(B) 6
(D) 9
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
72. Dry air is blown through acetone at 285 K and a constant pressure of 101.3 kPa. If it is
desired that 5 kg of acetone be evaporated what is the minimum amount of dry air required in
kilograms? The vapor pressure of acetone at 285 K is 16.82 kPa.
(A) 21.12
(C) 17.76
(B) 24.86
(D) 12.55
73. A mixture of acetone vapor and nitrogen gas at 101.3 kPa and 295 K contains acetone vapor
to the extent that it exerts a partial pressure of 15 kPa. The vapor pressure of acetone at 295
K is 26.36 kPa. The molal humidity is
(A) 0.0033
(C) 0.0987
(B) 0.0021
(D) 0.1738
74. Air at 101.3 kPa is blown across the bulb of a mercury thermometer. The bulb is covered
with a wick. The wick is immersed in an organic liquid (MW = 58). The reading of the
thermometer is 280.8 K. At this temperature the vapor pressure of the liquid is 5 kPa. Find
the air temperature given that the psychrometric ratio is 2 kJ/kg K and the latent heat of
vaporization of the liquid is 360 kJ/kg. Assume that the air which is blown is free from the
organic vapor.
(A) 299 K
(C) 305 K
(B) 291 K
(D) 310 K
75. Wood containing 40% moisture is dried to 5% moisture. What mass of water in kilograms is
evaporated per kg of dry wood?
(A) 0.24
(C) 0.32
(B) 0.37
(D) 0.45
76. The liquid effluent from a processing unit is discharged into a stream. The flow rate and
BOD of the stream before the discharge point are respectively 6 m 3/s and 3 x 10-5 g/L. The
measurements made immediately below the discharge point indicated a BOD of 5 x 10-3 g/L.
If the plant discharges the effluents at a rate of 16 x 103 m3/day, what is the BOD of the
effluent from the plant? (Note: Biochemical Oxygen Demand, BOD, is a measure of the
oxygen utilized by microorganisms during the oxidation of organic materials. BOD is a direct
measure of oxygen requirement and is directly proportional to the amount of organic waste
which has to be broken down.)
(A) 0.341
(C) 0.166
(B) 0.037
(D) 0.245
77. After a crystallization process, a solution of calcium chloride in water contains 50 parts of
calcium chloride per 100 parts of water. Solubility of calcium chloride in water at 298 K is
7.38 kmol of calcium chloride per 1000 kg of water. The weight of this solution necessary to
dissolve 200 kg of CaCl2.6H2O crystals at a temperature of 298 K is close to
(A) 88 kg
(C) 97 kg
(B) 121 kg
(D) 56 kg
SITUATION FOR PROBLEMS 78-79:
A spent lye sample obtained from a soap making unit contains 14% glycerol and 12% sodium
chloride by weight. It is concentrated at the rate of 6 000 kg h -1 in a triple effect evaporator until
the final solution contains 85% glycerol and 5% sodium chloride by weight. Assuming that 6%
of glycerol is lost by entrainment.
78. The amount of evaporation taken place in the system is about
(A) 93 kg/h
(C) 4347 kg/h
(B) 4398 kg/h
(D) 50 kg/h
79. The amount of salt crystallized out in the salt box of the evaporator is close to
(A) 625 kg/h
(C) 455 kg/h
(B) 755 kg/h
(D) 675 kg/h
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
SITUATION FOR PROBLEMS 80-81:
1000 kg of mixed acid of composition 40% H2S04, 45% HN03 and 15% H20 is to be produced by
strengthening waste acid of composition 30% H2S04, 36% HN03 and 34% H20 by weight.
Concentrated sulphuric acid of strength 95% and concentrated nitric acid containing 80% acid
are available for this purpose.
80. The amount (kg) of waste acid needed is about
(A) 84.32
(C) 76.39
(B) 70.22
(D) 62.19
81. The amount (kg) of concentrated nitric acid needed is close to
(A) 531
(C) 498
(B) 554
(D) 542
82. A crystallizer is charged with 100 kg of a solution containing 25% Ba(N03)2 in water. On
cooling 10% of the original water present evaporates. Calculate the yield (kg) of crystals
when the solution is cooled to 283 K. The solubility at 283 K is 7.0 kg Ba(N03)2/100 kg total
water.
(A) 17.7
(C) 24.6
(B) 15.2
(D) 20.3
SITUATION FOR PROBLEMS 83-85:
An aqueous solution containing 60% Na2S203 and 1% soluble impurities is diluted with water
and fed to a crystallizer where it is cooled in order to crystallize Na2S203·5H20. The crystals
carry 0.05 kg of solution (excluding impurities) per kg of crystals. The free water present in the
adhering solution is removed on drying the crystals. The final dried product contains not more
than 0.1 % impurity. The solubility of the pentahydrate is 1.5 kg Na2S203·5H20/kg free water. On
the basis of 100 kg of 60% solution,
83. The amount of water in kilograms added before cooling is close to
(A) 17.7
(C) 14.6
(B) 19.2
(D) 11.3
84. The amount (kg) of crystals formed is close to
(A) 65
(B) 54
(C) 59
(D) 70
85. The percentage recovery of the Na2S203 in the dried hydrated crystals is close to
(A) 77
(C) 83
(B) 89
(D) 71
86. A tannery extracts certain wood barks which contains 40% tannin, 5% moisture, 23% soluble
non-tannin materials and the rest insoluble lignin. The residue removed from the extraction
tanks contain 50% water, 3% tannin and 1% soluble non-tannin materials. What percent of
the original tannin remains unextracted?
(A) 7.7
(C) 8.3
(B) 6.9
(D) 5.2
SITUATION FOR PROBLEMS 87-89:
100 kg of oilseeds containing 49% oils, 40% pulp, 3% mineral salts and the rest moisture are
leached with hexane as the solvent. The underflow from the leaching operation contains 25%
hexane, 2.5% salts, 15% oil and 7.5% moisture. The overflow contains 25% oil which is distilled
to recover the entire hexane in pure form leaving behind the oil, water and salt. The underflow is
subjected to steam distillation which recovers 95% hexane.
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
87. The kilograms of hexane used is close to
(A) 121
(B) 117
MARCH 30 & APRIL 6, 2019
(C) 111
(D) 128
88. The percent of hexane used that is recovered from the underflow is close to
(A) 10
(C) 21
(B) 15
(D) 19
89. Percent recovery of oil is close to
(A) 82
(B) 70
(C) 76
(D) 65
SITUATION FOR PROBLEMS 90-91:
A drier is fed with wet solid to reduce the moisture content from 80% to 15%. The product
leaving the drier is admitted into an oven which further brings down the moisture to 2%. If the
drier can handle 1000 kg of wet solid per day,
90. The weight (kg) of products leaving the drier and the oven per day is close to
(A) 178
(C) 234
(B) 195
(D) 204
91. The percentage of the original water that is removed in the oven is close to
(A) 3.9
(C) 7.4
(B) 5.8
(D) 1.8
SITUATION FOR PROBLEMS 92-94:
Isopropyl alcohol and water can be separated by extraction with ethylene tetrachloride (C2Cl4).
100 kg of a solution containing 30% (weight) isopropyl alcohol and the rest water is mixed with
the solvent ethylene tetrachloride. After extraction, the raffinate phase analyzed 71% water,
28.1% isopropyl alcohol and 0.9% ethylene tetrachloride. The extract phase analyzed 94%
ethylene tetrachloride, 5.2% isopropyl alcohol and the rest water.
92. The amount (kg) of solvent is close to
(A) 39
(C) 54
(B) 45
(D) 49
93. The quantity (kg) of extract phase is close to
(A) 39
(B) 53
(C) 41
(D) 47
94. The percent extraction of isopropy1 alcohol is close to
(A) 6.9
(C) 8.2
(B) 8.8
(D) 7.8
95. Acetone is recovered from an acetone-air mixture containing 25% (volume) acetone by
scrubbing with water. Assuming that air is insoluble in water, determine the percent of
acetone in the entering gas that is absorbed if the gas leaving the scrubber analyzes 5%
acetone.
(A) 69
(C) 89
(B) 84
(D) 78
96. A gas mixture consisting of 65% N2 and 35% S03 by volume is admitted to an absorption
column at a rate of 4500 kg/h. It is contacted with a stream of 50% H2S04 flowing countercurrent to the gas stream at a rate of 5000 kg/h. The gases leave at 101.3 kPa. Water lost with
the exit gases exerts a partial pressure of 25.0 kPa. If the concentrated acid leaving the
bottom of the column contained 75.0% H2S04, what percent of the entering S03 is absorbed
and converted to acid?
(A) 66
(C) 84
(B) 71
(D) 78
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA
CHEMICAL ENGINEERING BOARD EXAM REVIEWER
MARCH 30 & APRIL 6, 2019
97. A continuous distillation column is used to regenerate solvent for use in a solvent extraction
unit. The column treats 200 kmol/h of a feed containing 10% (mol) ethyl alcohol and the rest
water. The overhead product is 89% (mol) alcohol and the bottom product is 0.3% (mol)
alcohol. The overhead is sent to the extraction unit and the bottom is wasted. What is the
daily requirement (kg) of make-up alcohol in the solvent extraction unit?
(A) 466
(C) 684
(B) 521
(D) 590
SITUATION FOR PROBLEMS 98-100:
An aqueous solution of methanol containing 20% (weight) methanol is to be separated into a
distillate product containing 97% (weight) methanol and a bottom product containing 2%
(weight) methanol. For treating 100 kg of feed with a reflux ratio of 3.5 on a weight basis,
98. The amount (kg/h) of distillate product is close to
(A) 19
(C) 24
(B) 34
(D) 29
99. The amount (kg) of vapor condensed in the condenser per kg of distillate is close to
(A) 6.4
(C) 6.0
(B) 4.5
(D) 5.3
100.The amount (kg) of vapor condensed in the condenser per kg of feed. is close to
(A) 0.76
(C) 1.11
(B) 0.96
(D) 0.85
COMPILED BY: ENGR. ALBERT D.C. EVANGELISTA