Reaction Kinetics, Gas Absorption, Drying Flashcards
(25 cards)
The second order irreversible elementary chemical reaction, 2A —–> B can be plotted in an x-y Cartesian plane. Determine the y-intercept.
A. CAO
B.1/CAO
C. 1/CAO^2
D. 1/2CAO
B.1/CAO
Discuss the following overall reaction with respect to order, catalysts, etc.
A. First order in A, second order in B, first order in C, product is inhibitor, fourth order
overall
B. First order in A, second order in B, first order in C, product is catalyst, fourth order
overall
C. First order in A, second order in B, first order in C, reactant is catalyst, fourth order
overall
D. First order in A, second order in B, first order in C, reactant is inhibitor, fourth order
overall
First order in A, second order in B, first order in C, product is catalyst,
fourth order overall
The half life for the given reaction was doubled as the initial concentration of a reactant is doubled. What is the order of the reaction?
A. 0
B.1
C. 1/2
D. 2
0
The concentration of A in a first order reaction A —–> B decreases
A. Linearly with time
B. Exponentially with time
C. Very abruptly toward the end of the
reaction
D. Logarithmically with time
B. Exponentially with time
The equilibrium constant of a chemical reaction
A. increases in the presence of catalyst
B. decreases in the presence of catalyst
C. remains unaffected in the presence of catalyst
D. can either increase or decrease; depends
on the type of catalyst
C. remains unaffected in the presence of catalyst
Reactions with high activation energy are
A. very temperature sensitive
B. temperature sensitive
C. always irreversible
D. always irreversible
A. very temperature sensitive
A second order reaction of the from A+B —-> C is called a pseudo-first order reaction when
A. CAO=CBO
B.CAO>CBO
C. CAO not equal to CBO
D. CBO>CAO
D. CBO>CAO
A first order irreversible reaction A —-> B is carried separately in a constant volume as well as in a variable volume reactor for a particular period. It signifies that
A. both conversion as well as concentration are the same in the two reactors
B. conversion in both will be the same but concentrations will be different in the two
reactors
C. both the conversion as well as concentrations will be different in the two reactors
D. none of these.
B. conversion in both will be the same but concentrations will be different in the two reactors
Which of the following is true about the elementary process?
A. A reaction involving only atoms is an elementary process.
B. A reaction that proceeds in only one step is an elementary process.
C. A reaction with zero order rate law is an elementary process.
D. All chemical reactions are elementary process.
B. A reaction that proceeds in only one step is an elementary process.
If a catalyst increases the rate of a reaction what happens to k(forward), the rate constant for the forward reaction, and to k(reverse), the rate constant of the reverse reaction?
A. k(forward) increases and k(reverse) increases
B. k(forward) increases and k(reverse) decreases
C. k(forward) increases and k(reverse) remains unchanged
D. k(forward) remains unchanged and k(reverse) decreases
A. k(forward) increases and k(reverse) increases
A liquid phase reaction: A+B < – > R+S, where k1=7 L/mol-min and k2=3 L/mol min is to take place in a 120-L CSTR. Two feed streams, one contaiming 2.8 mols A/L, and the other containing 1.6 mols B/L are to introduced in equal volumes into the reactor and 75% conversion of the limiting reactant is desired. What should be the flow rate of each stream? Assume a constant density throughout.
4 L/min
A liquid feed of pure A (1 mol/L) is treated in two reactors of two-liter volume each and reacts with the rate of rA=0.05 Ca2, mol/L-s. find what feed rate in L/min that will give a final outlet concentration of Ca=0.5 mol/L if two CSTRs in series are used?
8.49
A liquid feed of pure A (1 mol/L) is treated in two reactors of two-liter volume each and reacts with the rate of rA=0.05 Ca2, mol/L-s. find what feed rate in L/min that will give a final outlet concentration of Ca=0.5 mol/L if two CSTRs in parallel are used.
6
A liquid feed of pure A (1 mol/L) is treated in two reactors of two-liter volume each and reacts with the rate of rA=0.05 Ca2, mol/L-s. find what feed rate in L/min that will give a final outlet concentration of Ca=0.5 mol/L if two PFRs in parallel are used.
12
A liquid feed of pure A (1 mol/L) is treated in two reactors of two-liter volume each and reacts with the rate of rA=0.05 Ca2, mol/L-s. find what feed rate in L/min that will give a final outlet concentration of Ca=0.5 mol/L if a CSTR and PFR hooked up in parallel are used.
9
A liquid reactant stream (1 mol/L) passes through mixed-flow reactors in a series. The concentration of A in the exit of the first reactor is 0.5 mol/L. Find the concentration in the exit stream of the second reactor. The reaction is second order with respect to A and V2/V1=2.
0.25 mol/L
An aqueous reactant stream (4 A/L) passes through a mixed-flow reactor followed by a plug-flow reactor. Find the concentration at the exit of the plug-flow reactor. If in the mixed-flow reactor Ca = 1 mol/L. the reaction is second order with respect to A, and the volume of the plug-flow reactor is three times that of the mixed flow reactor.
0.1 mol/L
In general, operating pressure should be ___ and temperature ___ for an absorber, to minimize stage requirements and/or absorbent flow rate to lower the equipment volume required to accommodate the gas flow.
A. high, low
B. low, high
C. maximum, low
D. minimum, high
high, low
The reverse is true for stripping. However, the operating pressure should not be too high and operating temperature should not be too low as to ___ the feed gas.
A. Vaporize
B. condense
C. compress
D. none of these
condense
CO2 is to be absorbed from air using pure water in a countercurrent column. The ratio of mass fraction of CO2 in inlet air to that in exit air is 5 and the absorption factor 1.25. What is the theoretical number stages needed if the equilibrium line has a slope of 2?
2.63
CO2 is to be absorbed from air using pure water in a countercurrent column. The ratio of mass fraction of CO2 in inlet air to that in exit air is 5 and the absorption factor 1.25. What is the theoretical number stages needed if the equilibrium line has a slope of 2? If the liquid flow rate in the preceding item is 20 mol/s, what is the gas flow rate?
8 mole/s
What are the common symptoms of flooding?
A. Excessive entrainment, increase in pressure drop, increase in efficiency
B. Excessive entrainment, decrease in pressure drop, increase in efficiency
C. Excessive entrainment, decrease in pressure drop, decrease in efficiency
D. Excessive entrainment, increase in pressure drop, decrease in efficiency
Excessive entrainment, increase in pressure drop, decrease in efficiency
The initial moisture content of a food product is 77% (wet basis), and the critical moisture content is 30% (wet basis). If the constant drying rate is 0.1 kg H2O/ m2.s, compute the time required for the product to begin the falling rate drying period. The product has a cube shape with 5-cm sides, and the initial product density is 950 kg/m3.
53.2 s
A cabinet dryer is being used to dry a feed product from 68% moisture content (wet basis) to 5.5% moisture content (wet basis). The drying air enters the system at 54 degC and 10% RH. The product temperature is 25 degC throughout drying. Compute the quantity of air required for drying on the basis of 1 kg of product solid.
224.65 kg dry air/kg solids
