Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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1.
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The
reaction between hydrogen and sulfur below is exothermic.
H2(g) + S(s) ® H2S(g)
Which one of the
following factors will increase the rate of this reaction? a. | Decreasing the
temperature | c. | Adding more
sulfur | b. | Decreasing the volume of the
container | d. | Removing
H2S | | | | |
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2.
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The
rates of many chemical reactions double for a ten degree rise in temperature. Which one of the
following factors does not contribute to this change in rate with increasing
temperature? a. | Changes in the
average kinetic energy of the reacting species | c. | Changes in the number of very energetic
species | b. | Changes in the number of collisions in a given
time | d. | Changes in the
activation energy | | | | |
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3.
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Raising the temperature speeds up most chemical reaction. This is due to an
increase in which of the following?
I. The number of collisions occurring in a given
time II. The energy of each
collision a. | I
only
| c. | Both I and II | b. | II
only | d. | Neither I nor II | | | | |
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4.
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One way of producing hydrogen gas in the laboratory is to add an active metal
such as zinc to an acid such as hydrochloric acid. Which combination will produce hydrogen at
the fastest rate? a. | A one
gram piece of zinc in 100 cm3 of 1 | c. | One gram of zinc dust in 100 cm3 of 1 molar
HCl | b. | A one gram piece
of zinc in 100 cm3 of 3 mola | d. | One gram of zinc dust in 100 cm3 of 3 molar
HCl | | | | |
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5.
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An increase in the rate of a reaction is generally brought about by increases
in which of the following?
I. Reactant
concentration II. Particle
size III.
Temperature a. | I and II
only | c. | II and III
only | b. | I and III
only | d. | I, II and III | | | | |
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6.
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Reaction rates generally increase in response to a decrease in a. | catalyst
concentration. | c. | C.
particle size. | b. | B. reagent concentration | d. | D. temperature. | | | | |
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7.
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The
rates of many reactions increase dramatically with small increases in temperature. Which of the
following best accounts for this behaviour? a. | the activation energy decreases | c. | the number of molecular collisions
increases | b. | the enthalpy change of the reaction
increases | d. | the number of
molecules with the necessary energy increases
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8.
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Which
of the following would not usually be expected to affect the rate of a chemical
reaction? a. | Adding more
reactants. | c. | Increasing the
temperature. | b. | Removing some products. | d. | Adding a catalyst. | | | | |
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9.
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Which
of the following statements is (are) true?
I. In order for a reaction to occur,
reactant molecules must collide with each other.
II. A catalyst alters the rate of a reaction but
is not consumed during the reaction.
III. Endothermic
reactions are faster than exothermic reactions. a. | I only | c. | I and II only | b. | II
only | d. | I, II ,
III | | | | |
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10.
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When
100 cm3 of 1.0 M HCl are added to 1 g of granular zinc at 25ºC, hydrogen is
evolved. All of the following will increase the initial rate of hydrogen evolution
EXCEPT a. | substituting 2.0
M HCl for 1.0 M HCl. | c. | substituting
powdered zinc for granular zinc. | b. | using 200 cm3 of 1.0 M HCl instead of 100
cm3. | d. | increasing the
temperature of the 1.0 M HCl to 50ºC. | | | | |
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11.
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The
rate of this reaction represented by the equation below will be increased by which of the changes
listed?
H2(g) + I2(g) ®
2HI(g)
I.
Decreasing the volume of the container
II. Increasing the temperature a. | I only | c. | Both I and II | b. | II
only | d. | Neither I nor II
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12.
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The
reaction 2ICl(g) + H2(g) ®
I2(g) + 2HCl(g) is first order in both reactants. Which one of the statements is
true? a. | The rate of the
reaction will increase more is the ICl concentration is doubled than is the H2
concentration in doubled. | c. | The rate of the
reaction will increase equally if the ICl or the H2 concentration is
doubled. | b. | The rate of the reaction will increase more if the
H2 concentration is doubled than if the ICl concentration is
doubled.
| d. | Reaction rates
cannot be predicted, they can only be measured. | | | | |
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13.
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Which
of the factors below is (are) expected to affect the rate of the reaction in which gaseous water and
solid carbon form hydrogen and carbon monoxide: H2O(g) + C(s)
®
H2(g) + CO(g)
I. Concentration of H2O in the
reaction vessel II. Size of the
carbon particles a. | I
only | c. | Neither I nor
II | b. | II
only | d. | Both I and
II | | | | |
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14.
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Which
of the following factors can be responsible for altering the rate of a chemical
reaction?
I.
Concentration II. Equilibrium
constant III.
Temperature a. | I and II
only | c. | II and III
only | b. | I and III only | d. | II only | | | | |
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15.
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A
catalyst a. | creates another
reaction pathway.
| c. | is always a
solid. | b. | is consumed in a chemical
reaction. | d. | is always a
transition element. | | | | |
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16.
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It
has been found that the rates of many reactions are doubled by a 10-degree (ºC) rise in
temperature. The main reason for this is that a. | the energy of
activation decreases with temperature. | c. | the speed of molecules is dramatically increased with a 10
ºC increase in temperature. | b. | the energy of activation increases with
temperature. | d. | the fraction of
high-energy molecules increases exponentially with temperature. | | | | |
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17.
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A
catalyst will a. | alter the
mechanism (pathway) of a reaction. | c. | decrease DH for the reaction. | b. | increase
DH for the
reaction. | d. | decrease Ea for the forward reaction
only. | | | | |
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18.
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Which
of the following factors does not influence reaction rates? a. | Heat of
reaction
| c. | Size of solid
reactant particles | b. | B.
Reaction temperature | d. | Concentration of
reactants | | | | |
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19.
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Which
one of the following factors does not affect the rate of a chemical
reaction? a. | The enthalpy change of the reaction
| c. | The
concentration of the reactants | b. | The nature of the reactants
| d. | The presence of
a catalyst | | | | |
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20.
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Which
of the following would NOT affect the rate of a given chemical reaction? a. | A. The magnitude
of the equilibrium constant | c. | The reaction
temperature | b. | The size of solid reactant particles
| d. | The
concentration of the reactants | | | | |
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21.
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Which
one of the following statements about the reaction shown is incorrect?
2NaI(aq) + Cl2(g) D> 2NaCl(aq) + I2(s) a. | A. Lowering the
temperature of the reaction vessel would decrease the rate of the forward
reaction. | c. | Dissolving a
small amount of sodium iodide in the solution would increase the rate of the forward
reaction. | b. | Adding a small amount of solid iodine in the solution would
increase the rate of the reverse reaction and hence effectively decrease the rate of the forward
reaction | d. | Adding the inert
gas helium to the gaseous phase at constant volume would not affect the rate of
reaction.
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22.
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Which
graph best represents the change in concentration of products with time for a reaction as it goes to
completion?
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23.
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Reactions between aqueous solutions of sodium thisosulfate and acid can be followed by
timing the appearance of the solid sulfur that is produced. The time required for the appearance of
sulfur would be increased by which of the following changes. a. | raising
temperature | c. | adding a
catalyst | b. | diluting the solution | d. | increasing the concentration of the sodium
thiosulfate | | | | |
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24.
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The
reaction between excess calcium carbonate and hydrochloric acid can be followed by measuring
the volume of carbon dioxide produced with time. The results or one such reaction are shown below.
How does the rate of this reaction change with time and what is the main reason for this
change? a. | The rate
increase with time because the calcium carbonate particles get
smaller | c. | The rate
decreases with time because the calcium carbonate particles get smaller | b. | The rate
increase with time because the acid becomes more dilute | d. | The rate decreases with time because the acid becomes more
dilute. | | | | |
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25.
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The
rate of reaction of a strip of magnesium and 50 cm3 of 1 mol dm-3 HCl is
determined at 25ºC. In which case would BOTH new conditions contribute to an increase in
the rate of reaction? a. | Mg powder and 100 cm3 of 1 mol dm-3
HCl | c. | 100
cm3 of 1 mol dm-3 HCl at 30ºC | b. | Mg powder and 50
cm3 of 0.8 mol dm-3 HCl | d. | 50 cm3 of 1.2 mol dm-3 HCl at
30ºC | | | | |
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