increases the free energy change in the reaction.. does not increases and decreases the free energy change in the reaction.. can either decreases or increases the free energy change depe
Trang 1HO CHI MINH CITY UNIVERSITY OF FOOD INDUSTRY
Falculty of Chemical Engineering
CATALYSIS ENGINEERING COURSE
Multiple Choice Question
January - 2024
Trang 2Contents
Chapter 1- 2 1 Chapter 3 - 4 8
Trang 3Chapter 1- 2
1 The addition of catalyst during a chemical reaction alters which of the following quantities?
A Entropy B Internal energy
C Enthalpy D Activation energy
2 A catalyst is a substance which ………
A increases the equilibrium concentration of the product
B changes the equilibrium constant of the reaction
C shortens the time to reach equilibrium
D supplies energy to the reaction
3 A catalyst … ………
A increases the free energy change in the reaction
B decreases the free energy change in the reaction
C does not increases and decreases the free energy change in the reaction
D can either decreases or increases the free energy change depending on what catalyst
we use
4 Regarding criteria of catalysis which one of the following statements is not true?
A The catalyst is unchanged chemically during the reaction
B A small quantity of catalyst is often sufficient to bring about a considerable amount of the reaction
C In reversible reaction, the catalyst alters the equilibrium position
D The catalyst accelerates the rate of reaction
5 The work of enzymes in living system is ………
A oxygen transfer B to provide immunity
C to catalyze biochemical reactions D to provide energy
6 A chemical reaction is catalyzed by catalyst X So X ………
A increases the activation energy of reaction
B does not affect equilibrium constant of reaction
C decreases the rate constant of reaction
D decreases enthalpy of reaction
7 How enzymes increase the rate of reactions?
A By lowering activation energy B By increasing activation energy
C By changing equilibrium constant D By forming enzyme substrate complex
8 The process which is catalyzed by one of the products is called ………
A acid-base catalysis B autocatalysis
C negative catalysis D None of these
Trang 49 Which of the following statements about a catalyst is not true?
A It lowers the energy of activation
B The catalyst altered during the reaction is regenerated
C It does not alter the equilibrium
D It does not alter the rate constant of reaction
10 A catalyst can effect reversible reaction by ………
A changing equilibrium B slowing forward reaction
C attaining equilibrium in both direction D None of these
11 Which one of the following is an example for homogeneous catalysis?
A Manufacture of sulfuric acid by contact process
B Manufacture of ammonia by Haber’s process
C Hydrolysis of sucrose in presence of dilute hydrochloric acid
D Hydrogenation of oil
12 The efficiency of enzyme catalysis is due to its capacity to ………
A form a strong enzyme-substrate complex B change the shape of the substrate
C lower the activation energy of the reaction D form a colloidal solution in water
13 Which of the following reaction is an example for homogeneous catalysis?
14 A catalyst ………
A initiates a reaction
B lowers the activation energy of reacting molecules
C is capable of reacting with any one of the reactants
D can not be recovered chemically unchanged at the end of a chemical reaction
15 The equilibrium constant of a catalytic chemical reaction due to the presence of a catalyst
A increases B decreases
C remains unaffected D unpredictable from the data
16. When a catalyst increases the rate of forward reaction, the value of rate constant ……… …
A increases B decreases C does not change D becomes infinite
17. In autocatalytic reactions, ………
A one of the reactants acts as a catalyst B one of the products acts as a catalyst
C catalysts have very high selectivity D no catalyst is used
18 The reason why a catalyst increases the rate of reaction is that, it ………
A decreases the energy barrier for reaction B increases the activation energy
C decreases the molecular collision diameter D None of these
Trang 519 A reaction which is catalyzed by a base is catalyzed by all substances which have a tendency to
A lose a proton B gain a proton C gain an electron D None of these
20 A reaction which is catalyzed by an acid is also catalyzed by any substance, which has a
tendency to …………
A lose a proton B gain a proton C lose an electron D None of these
21 A catalyst ………
A increases the equilibrium concentration of the product
B changes the equilibrium constant of the reaction
C shortens the time to reach the equilibrium
D None of these
22. The equilibrium constant of chemical reaction in the presence of catalyst
A increases
B decreases
C remains unaffected
D can either increase or decrease (depends on the type of catalyst)
23. Catalyst is a substance, which chemical reaction
A increases the speed of a
B decreases the speed of a
C can either increase or decrease the speed of a
D alters the value of equilibrium constant in a reversible
24. Pick out the correct statement
A A catalyst speeds up the forward reaction but slows shown the reverse reaction
B Addition of catalyst changes the equilibrium constant
C Pressure changes do not change the equilibrium concentrations
D The composition of equilibrium is changed by catalyst
25. Oxidation of SO2 to SO3 in the presence of nitric oxide (NO) as catalyst
What's kind of the catalyst for the above reaction?
A Homogenous catalyst
B Heterogeneous catalyst
C Heterogeneous catalysts and homogenous catalysts
D Undefined
26. Manufacture of ammonia by Haber’s process using finely divided iron as catalyst
What's kind of the catalyst for the above reaction?
A Homogenous catalyst
B Heterogeneous catalyst
Trang 6C Heterogeneous catalysts and homogenous catalysts
D Undefined
27 In acid catalysis, the H+ (or a proton donated by Bronsted acid) forms an intermediate with the reactant, which then reacts to give back the proton For example, the mechanism of ketoenol tautomerism of acetone is:
Substance X is a/an ……
A reactant B catalysts C product D intermediate
28. For example of Homogeneous Catalytic Mechanism, the reaction takes place by a two-step mechanism as shown below:
Reaction intermediate is ………
29. Which statement about catalyst is universally correct?
A A catalyst does not take part in reaction
B A catalyst remains unchanged physically and chemically
C A catalyst lowers the energy of activation
D A catalyst is highly specific in action
30. In a reversible reaction, a catalyst ………
A increases the rate of forward reaction only
B increases the rate of forward reaction to a greater extent than of the backward reaction
C increases the rate of forward reaction to and decreases that of the backward reaction
D increases the rate of forward and backward reaction equally
31. The decomposition of CH3CHO in presence of I2 involves:
CH3CHO + I2 → CH3I + HI + CO
CH3I + HI → CH4 + I2
and rate = k[CH3CHO][I2] Is I2 catalyst for the reaction?
A No; I2 is intermediate
B Yes; the first step being slow and thus rate is given = k[CH3CHO][I2]
C No; HI is catalyst for the reaction
D No; I2 is reactant for the reaction
32. Mark the incorrect statement: A catalyst …………
A alters the velocity of reaction
B changes the energy of activation of given process
Trang 7C does not alter the state of equilibrium
D is a reactant required in small quantity
33 The exothermic reaction between substances A and B is presented in the plot below
Catalyst-induced preparation of the substance AB follows the pathway …
A (1) B (2) C (3) D None is correct
34 The catalyzed decomposition of hydrogen peroxide is believed to take place by a two-step path:
Step 1: H2O2 (aq) + I– (aq) → H2O + IO– (aq)
Step 2: H2O2 (aq) + IO– (aq) → H2O + O2 (g) + I– (aq)
2H2O2 (aq) → 2H2O + O2 (g)
Choose the correct statement about this reaction
A I– is a catalyst B H2O is a reactant
C IO– is a product D O2 is an intermediate
takes place by mechanism as follow:
(X)
Substance X takes part in this reaction as a/an ………….…
A catalyst B activated complex C intermediate D inhibitor
takes place by mechanism as follow:
The energy profile of the reaction should be:
Trang 837 The mechanism of the reaction: A + 2B → D + E; H = –ve is
Step I: A + 2B → C (slow)
Step II: C → D + E (fast)
The energy profile of the reaction should be:
38 Based on the following reaction profile, how is the enthalpy change of the reaction?
A Negative B Positive C Zero D Infinitive
39 Based on the following reaction profile, how many transition states are there in the reaction:
Reactant → Product ?
40 Based on the following reaction profile, how many intermediates are formed in the reaction:
A → D?
Trang 941 The following graph shows two different reaction pathways for the same overall reaction at the
same temperature Choose the correct statement
A The reaction rate is faster for the red path than for the blue path
B The equilibrium constants are different in two paths
C For both paths, the rate of the reverse reaction is faster than the rate of the forward
reaction
D The energy change ∆E is the same for both paths
Trang 10Chapter 3 - 4
1 The phenomenon of concentrations of molecules of a gas or liquid at a solid surface is called
A. absorption B. adsorption C. catalysis D. None of these
2 In gas masks, the poisonous gases are removed by the adsorbent by the process of _
A. absorption B. adsorption C. catalysis D. none of these
3 The adsorption of hydrogen on charcoal is
A. physical adsorption B. chemical adsorption C. sorption D. none of these
4 Heat of adsorption is defined as the energy liberated when of a gas is adsorbed on the
solid surface
A. 1 molecule B. 1 g C. 1 mole D. 1 kg
5 Which one of the following characteristics is associated with adsorption?
A. G is negative but H and S are positive
B. G, H and S all are negative
C. G and H are negative but S is positive
D. G and S are negative but H is positive
6 For physical adsorption of a gas on solid adsorbent
A. H is positive B. S is negative C. G is negative D. F is positive
7 Adsorption of gases on solid surface is generally exothermic because
A. chemical bonds are always formed
B. adsorbate decreases the surface energy of adsorbent
C. entropy increases
D. free energy increase
8 Which of the following is correct?
A. Adsorption is always exothermic
B. Adsorption is always endothermic
C. Physical adsorption is endothermic whereas chemical adsorption is exothermic
D. Chemical adsorption is endothermic whereas physical adsorption is exothermic
9. The heat of adsorption in physical adsorption lies in the range _ kJ/mole
A. – (1–10) B. – (10–400) C. – (4–100) D. – (100–400)
10 The enthalpy of adsorption in chemisorption lies in the range _ kJ/mole
A. – (40 – 400) B. – (100 – 400) C. – (4 – 100) D. – (1 – 10)
11 Physical adsorption is appreciable at
A. higher temperature B. lower temperature C. room temperature D. 100°C
Trang 1112 Rate of physical sorption increases with _
A. decrease in temperature B. increase in temperature
C. decrease in pressure D. decrease in surface area
13 Which characteristic of adsorption is wrong?
A. Physical adsorption decreases with increase in temperature
B. Physical adsorption increases with increase in temperature
C. Physical adsorption is a reversible process
D. Adsorption is limited only to the surface
14 Which one of the following characteristics is not correct for physical adsorption of a gas on
solid?
A. Adsorption is reversible
B. Adsorption increase with increase in temperature
C. Absorption is spontaneous
D. Both enthalpy and entropy of adsorption are negative
15 Which one of the following is an incorrect statement for physical sorption?
A. It is a reversible process B. It requires less heat of adsorption
C. It requires activation energy D. It takes place at low temperature
16 Which one of the following is not a correct statement?
A. Physical adsorption is reversible in nature
B. Physical adsorption involves Vander Waal’s forces
C. Rate of physical adsorption increases with increase of pressure on the adsorbate
D. High activation energy is involved in physical adsorption
17 Which one of the following is not applicable to chemisorption?
A. Its heat of adsorption is high B. It takes place at high temperature
C. It is reversible D. It forms mono-molecular layers
18 Which of the following is not a characteristic of chemisorption?
A. Adsorption is irreversible
B. Adsorption decreases with increase in temperature
C. Adsorption is specific
D. Adsorption increases with increase of surface area
19 Which one of the following is not applicable to chemisorption?
A. High magnitude of ΔH B. Occurs at higher temperature
C. It is reversible D. It forms mono layer
20 The nature of bonding forces in adsorption is _
A. purely physical like Vander Waal’s force B. purely chemical
C. both, physical and chemical, always D. None of these
21 In physical adsorption, the forces associated are _
A. ionic bond B. covalent bond
Trang 12C. vander Waal’s forces D. All of these
22 The nature of bonding forces in adsorption is _
A. purely physical such as Van der Waal’s forces
B. purely chemical
C. both chemical and physical always
D. None of these
23 In physical adsorption, the gas molecules are held to the solid surface by _
A. hydrogen bond B. sigma bond
C. pi bond D. van der Waals’ forces
24 The relationship between equilibrium pressure of gas and its amount adsorbed on the solid
adsorbent at constant temperature is called _
A. chemisorption B. adsorption isobars
C. adsorption isotherms D. None of these
25 The adsorption of a gas on a solid surface varies with pressure of the gas in which of the
following manner?
A. Fast → slow → independent of the pressure
B. Slow → fast → independent of the pressure
C. Independent of the pressure → fast → slow
D. Independent of the pressure → slow → fast
26 Langmuir isotherms hold at low pressure but fail at _
A. low temperature B. high pressure C. intermediate pressure D. None of these
27 Freundlich isotherms is not applicable at _
A. high pressure B. low pressure C. 273 K D. room
temperature
28 How many layers are adsorbed in chemical adsorption?
A. 1 B. 2 C. 3 D. 1 or more
29 Multi-molecular layers are formed in _
A. absorption B. physical adsorption
C. chemisorption D. reversible adsorption
30 Which among the following statements is false?
A. Increase of pressure increases the amount of adsorption
B. Increase of temperature may decrease the amount of adsorption
C. The adsorption may be monolayered or multilayered
D. Particle size of the adsorbent will not affect the amount of adsorption
31 A finely divided state of catalyst is more efficient because in this state:
A less active centers are formed B. more surface area is available
C more energy is stored in the catalyst D. more molecules are formed