University of Baghdad - College of Engineering
Department of Chemical Engineering
M. Sc. Entry Exam
Date: 20/6/2021
Time: 3h (9:00 AM)
Q1: Choose the right answer of the following articles. (60 Marks)
1. How is a coal combustion reaction classified?
a. Heterogeneous non-catalytic.
c. Slow heterogeneous.
b. Heterogeneous catalytic.
c. Homogeneous catalytic.
2. A reactor performance equation (output of a reactor) depending on:
a. Reaction kinetics only.
b. Contacting pattern only.
c. Input, kinetics, and contacting pattern.
d. None of the above!
3. The reaction rate for component D according to the reaction rate of component A, for the liquid phase
reaction aA  bB  cC  dD is
a
a. rD  (rA )
d
d
b. rD  (rA )
a
d
c. rD  (rA )
a
d
d. rD 
(r )
a  b  c A
4. We are constructing a 1-liter popcorn popper to be operated in steady flow. First tests in this unit show that
1 liter/min of raw corn feed stream produces 28 liter/min of mixed exit stream. If independent tests show that
when raw corn pops its volume goes from 1 to 31, then the fraction of raw corn is popped in the unit is:
a. 0.9643
b. 0.9333
c. 0.9000
d. None of the above, calculate it
5. Milk I pasteurized if it is heated to 63 °C for 30 minutes, but if it is heated to 74 °C it only needs 15 seconds
for the same results. Then the activation energy of the sterilization process is:
a. 422 kJ/mole
b. 138 kJ/mole
c. 73 kJ/mole
d. 18 kJ/mole
6. The reaction rate value of oxidation reaction occurred in 0.21 m3 reactor and consumed 15 mole of oxygen
per 2 seconds is:
a. -rO2= 0.03
b. -rO2= 1.58
c. -rO2= 35.71
d. -rO2= 142.86
7. The disappearance of A in the gas reaction 2A  R occurring in variable volume constant pressure
reactor. If the volume of the reaction mixture, starting with 80% A, and decrease by 20% in 3 minutes, so
the first order reaction rate constant is:
a. 4.328 min-1
b. 0.400 min-1
c. 0.231 min-1
d. 0.005 min-1
Page 1 of 6
University of Baghdad - College of Engineering
Department of Chemical Engineering
M. Sc. Entry Exam
Date: 20/6/2021
Time: 3h (9:00 AM)
8. The unit of the reaction rate constant for second-order reaction is:
a. (time)-1
b. (conc.) (time)-1
c. (conc.)-1(time)-1
d. Dimensionless
9. ------------------------ is Newton's law of viscosity.
a. 𝜏 = 𝜇 𝛾̇ .
b. 𝛾̇ =
𝜏
𝜇
c. 𝜇 =
.
𝜏
.
𝛾̇
d. all the others.
[where: 𝜏 is the shear stress (Pa) , 𝜇 is dynamic viscosity (Pa.s) and 𝛾̇ is the shear rate (s-1) ].
10. A pressure drop occurs in pipes because of ----------------------.
a. frictional viscous forces.
b. forces acting outside the pipe .
previous.
11.The pressure drop in a pipe is defined as ∆p = 8 𝑗𝑓 (
a. the total length of the pipe.
c. the entrance length.
∑ 𝐿𝑒 𝜌𝑢2
𝑑𝑖
)
2
c. shear rate .
d. none of the
where∑ 𝐿𝑒 is ------------.
b. the sum of the equivalent lengths of various valves and fittings.
d. none of the previous
12. The pressure drop of flow of non-Newtonian fluids in pipes is a function of many factors such as:----------------.
a. density.
𝐿
b. velocity.
c. 𝑑 .
d. all the others.
13. The mean linear velocity of a liquid flowing in a circular pipe can be written as ----------.
𝑄
a. u = 𝜌𝑄 .
b. u = 𝜋 𝑑2 /4 .
c. u = 𝜌𝑣.
d. u =
𝑀
𝐴
.
[where: u is the mean linear velocity, Q is the volumetric flowrate, d is the inner pipe diameter, v is the
volume of the liquid, M is the mass of the liquid, and A is the cross-sectional area of flow].
14. Consider two identical centrifugal pumps connected in parallel, the total head ∆ℎ𝑇 is --------------------.
a. ∆ℎ𝑇 = ∆ℎ1 = ∆ℎ2 .
b. ∆ℎ𝑇 = ∆ℎ1 + ∆ℎ2 .
c. ∆ℎ𝑇 = 𝑄1 + 𝑄2 .
d. ∆ℎ𝑇 = 𝑄1 = 𝑄2 .
15. High- viscosity liquids can be mixed thoroughly and efficiently in a tank by using -----------.
a. six- blade flat turbine.
b. marine propeller.
c. anchor agitator.
d. helical screw.
16. The net positive suction head NPSH can be defined by the relation:
( 𝑝𝑠 − 𝑝𝑣𝑝 )
NPSH = zs +
a. suction.
𝜌𝑔
- ℎ𝑓𝑠
where: zs is the ----------- head.
b. static.
17. 1 Liquids transmit heat by:
a. Conduction.
b. Convection.
c. discharge
c. Radiation.
18. Thermal diffusivity of the solid is :
Page 2 of 6
d. loss of friction.
d. All of the above.
University of Baghdad - College of Engineering
Department of Chemical Engineering
M. Sc. Entry Exam
Date: 20/6/2021
Time: 3h (9:00 AM)
a. (k/ρ Cp) with the dimensions of m2/s
b. (ρ k/Cp) with the dimensions of m2/s
c. (ρ k Cp) with the dimensions of m2/s
19. 5.67x10-8 W/m2 K4 .
a. is Biot number .
b. is Stefan-Boltzmann's constant.
c. is emissivity of a gray body.
20.
a. Gases are poor conductors of heat, and circulating currents are small, so convection is therefore much more
important than conduction in a gas.
b. Gases are good conductors of heat, with no circulating currents, so convection is therefore much more
important than conduction in a gas.
c. Gases are poor conductors of heat, and circulating currents are difficult to suppress; convection is therefore
much more important than conduction in a gas.
21. In the conduction of heat through a composite wall:
a. 𝑄 =
b. 𝑄 =
∆𝑇
∑𝑛
𝑖 𝑥𝑖 𝑘𝑖
𝑡𝑜𝑡𝑎𝑙 𝑑𝑟𝑖𝑣𝑖𝑛𝑔 𝑓𝑜𝑟𝑐𝑒
𝑡𝑜𝑡𝑎𝑙 (
𝑡ℎ𝑒𝑡𝑟𝑚𝑎𝑙 𝑟𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒
)
𝑎𝑟𝑒𝑎
c. Either of the above
22. Baffles in a shell and tube heat exchanger are used :
a. Across the tube bundle in order to increase the velocity over the tubes.
b. In the tubes to increase the velocity in the tubes.
23.
a. In natural convection, the currents arise from the heat transfer process itself, so Nu is a function of both
Grashof and Prandtl numbers.
b. In forced convection, the currents arise from the heat transfer process itself, so Nu is a function of both
Reynold’s and Prandtl numbers.
c. In forced convection, the circulating currents are produced by an external factor, so Nu is a function of both
Reynold’s and Prandtl numbers.
24. In dropwise condensation,
a. the rate of heat transfer is higher than that of filmwise condensation.
b. the rate of heat transfer is smaller than that of filmwise condensation.
25. Fickʼs first law is given by the formula:
a. 𝑗𝐴 = −𝐷𝐴𝐵
𝑑𝐶𝐴
𝑑𝑦
Page 3 of 6
University of Baghdad - College of Engineering
Department of Chemical Engineering
M. Sc. Entry Exam
Date: 20/6/2021
b. 𝑗𝐴 = −𝐷𝐴𝐵
c. 𝑗𝐴 = −
Time: 3h (9:00 AM)
𝑑𝐶𝐴
𝑑𝑡
𝐷𝐴𝐵 𝑑𝐶𝐴
𝑅𝑇 𝑑𝑦
26. Diffusivity increases with
a. increasing the pressure.
b. Increasing the temperature.
c. both a and b.
27. In the gas-liquid absorption column, for obtaining the maximum efficiency,
a. liquid stream should be distributed uniformly.
b. gas stream should be distributed uniformly.
c. both a and b.
28. With increasing temperature, the leaching rate increases due to
a. decreased liquid viscosity and increased diffusivity.
b. increased diffusivity and saturation concentration.
c. Neither a nor b.
29. In distillation process with saturated liquid feed,
a. q > 1.
b. q = 1.
c. q < 1.
30. The reflux to a distillation column is 100 moles/h, when the overhead product rate is 50 moles/h. The
reflux ratio is
a. 50
b. 0.5
c. 2
31. Experimental determination of ……………. is done by wetted wall column method.
a. mass transfer coefficient
b. diffusivity
c. HETP
32. NA/NB = -1 means:
a. stagnant diffusion.
b. Equi-molecular counter diffusion.
c. Unequi-molecular counter diffusion.
33. A difference of temperature of 25 ⁰C is equivalent to a difference of
a. 72 ⁰F
b. 45 ⁰F
c. 32 ⁰F
c. 25 ⁰F
34. If du represents the increase in internal energy of a thermodynamic system and dw the work done by the
system, which of the following statement is true?
a. du = dw in isothermal process
b. du = dw in adiabatic process
c. du = -2 dw in an aidabadic process
d. du = -2 dw in an isothermal process
35. In thermodynamics, the work done by the system is considered ................. and the work done on the system
is considered …………..
a. Positive, zero
b. negative, Positive
c. zero, negative
d. Positive, negative
Page 4 of 6
University of Baghdad - College of Engineering
Department of Chemical Engineering
M. Sc. Entry Exam
Date: 20/6/2021
Time: 3h (9:00 AM)
36. In an isochoric Process T1 = 27 ⁰C and T2 = 127 ⁰C then (P1/P2) will be equal to
a. 0.213
b. 2/3
c. 4/3
d. 3/4
37. A Carnot cycle consists of the following steps:
a. Two isothermal and two isentropic.
b. Two isobaric and two isothermal.
c. Two isochoric and two isobaric.
d. Two isothermal and two isochoric.
38. The compressibility factor for an ideal gas is 1. Its value for any other real gas is
a. 1
b. < 1
c. > 1
d. Either (b) or (c), depends on the nature of the gas
39. A refrigeration cycle is the same as a …………....cycle,
a. Turbine
b. Heat engine
c. Reversed heat engine
d. None of these
40. Enthalpy of a gas depends upon its
a. Temperature
b. Mass
c. Volume
d. Pressure
_________________________________________________________________________________
Q2: Answer the following questions. (40 Marks)
1. Find the maximum concentration of R and when it is reached, for the elementary reactions in series:
2. Apply Bernoulli's equation on water (density 1000 Kg/m3) flowing through an inclined pipe between section
1 and 2 to calculate the friction losses ℎ𝑓 if the following data are available [Note: the correction factor, ∝,
can be assumed 0.5].
Elevation ( m)
Pressure (Pa)
Velocity (m/s)
Section 1
E
4*105
25
Section 2
20
1.013*105
10
3. In an oil cooler, 216 kg/h of hot oil enters a thin metal pipe of diameter 25 mm. An equal mass of cooling
water flows through the annular space between the pipe and a larger concentric pipe; the oil and water moving
in opposite directions. The oil enters at 420 K and is to be cooled to 320 K. If the water enters at 290 K, what
length of pipe will be required? Take coefficients of 1.6 kW/m2.K on the oil side and 3.6 kW/m2.K on the
water side, and 2.0 kJ/kg K for the specific heat of the oil.
Page 5 of 6
University of Baghdad - College of Engineering
Department of Chemical Engineering
M. Sc. Entry Exam
Date: 20/6/2021
Time: 3h (9:00 AM)
4. From principles, derive the equation of mass transfer rate with stagnant diffusion.
5. Air expands from 700 kPa, 650 K, to 200 kPa in an isentropic process. Calculate the final temperature and
change in enthalpy (J/mol). {Cp = (7/2) R}.
R = 8.314 J/mol.K
𝐾1
6. The first order reversible reaction 𝐴 ↔ 𝐵 occur in continuous stirred tank reactor. Find the differential
K2
equation which relate CA with time.
7. Solve the nonlinear equation;
𝑦2 + 𝑥2
𝑑𝑦
𝑑𝑦
= 𝑥𝑦
𝑑𝑥
𝑑𝑥
8. By using the Laplace transformation, solve the equation
𝑑𝑦
+ 2𝑦 = 𝑒 𝑡
𝑑𝑡
𝑦(0) = 1
Page 6 of 6