Chemical Process Analysis Concept Inventory – Project 4
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Answer
Key
The purpose of this multiple-choice inventory is to help you assess your understanding of basic concepts in chemical
process analysis. Please do the following:
1.
You are to complete the “Project P4 Concept Inventory, Part A” survey in Team 360 by yourself,
using the questions below. Write your selected options (like A or C) for each question on some scrap paper.
2.
After all members in your team have completed this survey, your team is to meet, compare answers,
resolve any differences, and be ready to state “why” for each answer.
3.
Member Diamond is to complete the “Project P4 Concept Inventory, Part B” survey in Team 360
using the consensus answers of your team.
4.
Your team is to consult with the instructor and address the “why’s” for your team’s answers.
∟ What principle did you use to figure out the answer?
Please return this paper copy of the concept inventory to the instructor before you leave class today.
Q01. At 50 kPa a substance boils at 70ºC. The substance is observed to boil when the pressure is
increased to 100 kPa. At a pressure of 100 kPa, the substance will boil at:
a) The same temperature (i.e., at 70ºC) because for liquids the boiling point is
independent of the pressure.
b) A temperature less than 70ºC because for all compounds the boiling point
decreases with increasing pressure.
c) A temperature greater than 70ºC because for all compounds the boiling point
increases with increasing pressure.
how boiling point varies with temperature
d) 140ºC.
e) An unknown temperature. There is insufficient information to answer whether
the temperature will be less than, greater than or equal to 70ºC.
Q03. Generally if the pressure is held constant the density of a gas does what with increasing
temperature?
a) decreases.
ideal gas: rho = M * P / (R*T)
b) stays the same.
c) increases.
d) can’t answer as it depends on the type of gas.
e) it may increase or decrease depending on how close it is to its critical point.
Q04. Which ball in the list below has the highest potential energy relative to the ground? Assume that
all the balls have the same mass.
a) a stationary ball sitting on a table 80 cm above the ground.
b) a ball moving vertically upwards as it passes through a height 130 cm.
c) a ball moving vertically downwards as it passes through a height of 150 cm.
d) a ball moving horizontally at a height of 120 cm and at a speed of 1 m/s.
e) a ball at rest on the ground but at a temperature of 800ºC.
delta PE = m * g * h
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Chemical Process Analysis Concept Inventory – Project 4
Answer
Key
DO NOT WRITE ON THIS PAPER COPY!
Q06. A gas is flowing along through a pipe at a rate of 150 litre/min when it enters a heater. When it
emerges its temperature has increased by 50ºC. The pressure is approximately atmospheric. What
is the volumetric flow rate of the gas leaving the heater?
a) less than 150 litre/min.
material equation and ideal gas law:
b) 150 litre/min.
n1 = n2;
P1* V1 = n1*R* T1
c) greater than 150 litre/min.
P2* V2 = n2*R* T2
d) either less than or equal to 150 litre/min.
V2 = V1* (T2 / T1)
e) impossible to say as it depends on the nature of the gas.
Q08. Which one of the following statements is false?
a) The boiling point of water at one standard atmosphere is 100ºC.
b) Steam cannot exist in a room at temperatures less than 100ºC if the total pressure
in the room is one standard atmosphere.
c) Water can only exist at a temperature of 200ºC if the pressure is very much
greater than one standard atmosphere.
d) The temperature at which water boils increases with increasing pressure.
e) The wisps of ‘steam’ seen coming off the surface of a hot mug of tea or coffee on
a cold day are actually water vapor.
vapor pressure and partial pressure of one-condensable water vapor (i.e., steam)
Q15. 1 kg of a particular gas at 10ºC is mixed with 1 kg of the same gas at 90ºC. What will be the
temperature of the 2 kg gas sample?
a) Less than 50ºC.
b) 50ºC.
only if heat capacity is not function of T
c) Greater than 50ºC.
d) Either less than or equal to 50ºC.
e) Impossible to say as it depends on the thermal properties of the particular gas.
energy balance :
T1
m1

CˆVGˆ dT
m1Uˆ1
T2
T1

T

 m2
T0
m1
 m2Uˆ 2
 m3Uˆ 3
T3

CˆVGˆ dT
 m3 CˆVGˆ dT
T0

Cˆ PG  R dT
T2
 m2
0

T
T0

Cˆ PG  R dT
0
T3
 m3
 Cˆ
T
0
assuming constant pressure for an ideal gas
but Cˆ G  a  bT  bT 2  bT 3
P
50 C is only correct if Cˆ PG  a
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G
P

 R dT
Chemical Process Analysis Concept Inventory – Project 4
DO NOT WRITE ON THIS PAPER COPY!
Answer
Key
Q26. The chemical reaction of 2 A + 1 B → 1 P takes place in the following steady-state reactor:
20 g-mol/s
F
pure A
reactor
60 g-mol/s
H
? g-mol/s
G
pure B
A chemical engineer has determined that the extent of reaction is 5 g-rxn/s, in order to maintain the
desired molar conversion in the reactor. What is the total molar flow rate of the exit Stream H?
a) Nothing can be determined without the molecular weights.
b) It is 90 g-mol/s.
c) It is 80 g-mol/s.
d) It is 70 g-mol/s.
nF + nG - nH - 2 RI = 0
e) It is 60 g-mol/s.
Q27. What is the percent molar conversion of chemical Compound A in Question 26?
a) It is
0%.
b) It is
25%.
nF - nH,A - 2 RI = 0
c) It is
50%.
conversion = 2 RI / nF
d) It is
75%.
e) It is 100%.
Please return this paper copy of the concept inventory to the
instructor before you leave class today.
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