Download Test 539 Kinetics Name Multiple Choice Identify the letter of the

Test 539 Kinetics Name __________________________________________________________________
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____
1. For the reaction below relate the rate of disappearance of hydrogen to the rate of formation of
ammonia.
N2(g) + 3H2(g) → 2NH3(g)
a.
b.
c.
d.
e.
____
2. The elementary steps for a catalyzed reaction are shown below. Identify the catalyst? Identify the
reactive intermediate?
H2O2(aq) + I-(aq) → H2O(l) + IO-(aq)
IO-(aq) + H2O2(aq) → H2O(l) + O2(g) + I-(aq)
a.
b.
c.
d.
e.
____
The catalyst is H2O(l); the reactive intermediate is I-(aq).
The catalyst is IO-(aq); the reactive intermediate is I-(aq).
The catalyst is I-(aq); the reactive intermediate is H2O2(aq).
The catalyst is I-(aq); the reactive intermediate is IO-(aq).
The catalyst is H2O2(aq); the reactive intermediate is I-(aq).
3. Which of the statements concerning the relative rates of reaction is correct for the chemical equation
below?
N2(g) + 3H2(g)
a.
b.
c.
d.
e.
2NH3(g)
The rate of disappearance of N2 equals 1/4 the rate of formation of NH3.
The rate of disappearance of N2 equals the rate of formation of NH3.
The rate of disappearance of N2 is twice the rate of formation of NH3.
The rate of disappearance of N2 is three times the rate of disappearance of H2.
The rate of disappearance of N2 is 1/3 the rate of disappearance of H2.
____
4. All of the following statements are correct EXCEPT
a. a heterogeneous catalyst is in a different phase from the reaction mixture.
b. enzymes are protein molecules that catalyze reactions.
c. catalysts are not consumed in reactions.
d. a reaction mechanism describes the path of a reaction at the molecular level.
e. elementary steps in a reaction mechanism are always unimolecular.
____
5. What are the units of the rate constant for the rate expression for the following chemical equation?
2NO(g) + Cl2(g) → 2NOCl(g)
rate = k[NO]2 [Cl2]
a.
b.
c.
d.
e.
____
mol/L·s
mol2/L2·s
L/mol·s
L2/mol2·s
L3/mol3·s
6. Write the correct rate expression for the chemical reaction below.
2C2H5OH(g) + 6O2(g) → 4CO2(g) + 6H2O(g)
a.
b.
c.
d.
e.
rate = k[C2H5OH] [O2]
rate = k[C2H5OH]2 [O2]6
rate = k[C2H5OH] [O2]3
rate = k[C2H5OH]2 [O2]
not enough information to solve
____
7. The effect of a catalyst on a chemical reaction is to
a. enable an alternate path for the reaction that has a lower activation barrier.
b. increase the energy of the products.
c. increase the activation barrier for the forward reaction.
d. increase the energy of the reactants.
e. increase the frequency of collisions between reactants and products.
____
8. For the second-order decomposition reaction,
2A → B
rate = k[A]2
which of the following relationships yields a straight line plot?
a. ln[A] versus k
b. ln [A]2 versus t
c. ln[A] versus t
d. 1/[A] versus t
e. 1/[A] versus k
____
9. Which of the following expressions corresponds to the integrated rate equation for a first-order
decomposition reaction?
a. [A] = -kt
b. [A] = [A]0 - kt
c. ln[A] = ln[A]0 - kt
d.
= -kt
e.
kt
____10. A possible reaction mechanism for the reaction of nitrogen dioxide with carbon monoxide is
2NO2(g) → NO3(g) + NO(g)
NO3(g) + CO(g) → NO2(g) + CO2(g)
(slow)
(fast)
What is the overall reaction and the most probable rate law for the reaction?
a. NO2(g) + CO(g)
NO(g) + CO2(g); rate = k[NO2]
b. NO2(g) + CO(g)
NO(g) + CO2(g); rate = k[NO2]2
c. NO2(g) + CO(g)
NO(g) + CO2(g); rate = k[NO3][CO]
d. 2NO2(g) + CO(g)
NO(g) + CO2(g); rate = k[NO2][ NO3][CO]
e. 2NO2(g) + CO(g)
NO(g) + CO2(g); rate = k[NO3][CO]
____ 11. A first-order reaction has a half-life of 1.34 103 hours. If the initial concentration of reactant is
8.00 M, what is its concentration after 4 half-lives?
a. 0.25 M
b. 0.50 M
c. 1.00 M
d. 2.00 M
e. 4.00 M
____ 12. Which of the following may affect the value of the rate constant for a chemical reaction?
1.
2.
3.
a.
b.
c.
d.
e.
the presence of a catalyst
the concentrations of the reactants
the temperature of the reactants
1 only
2 only
3 only
1 and 3
1, 2, and 3
Problems
Complete the following problems. Show all work.
1) Consider the following reaction:
2HgCl2(aq)
+
C2O4-2(aq)
→
2Cl-(aq)
+
2CO2(g)
+
Hg2Cl2(s)
The initial rates of the disappearance of oxalate were determined at varying concentrations of mercury(II)
chloride and oxalate.
[HgCl2] (M)
[C2O4-2] (M)
Rate (M/s)
0.164
0.15
3.2 x 10-5
0.164
0.45
2.9 x 10-4
0.082
0.45
1.4 x 10-4
0.246
0.15
4.8 x 10-5
a) What is the rate law of this reaction?
b) What is the value of the rate constant?
c) What is the reaction rate when the concentration of HgCl2 is 1.00M and that of C2O42- is 0.25M at the same
temperature as the data collected?
2) NO catalyzes the decomposition of N2O possibly by this proposed reaction:
2NO(g) +
2NO2(g)
2N2O(g)
→
→
2NO(g)
2N2(g) +
+
O2(g)
a) Write a chemical equation for the overall reaction:
2NO2(g)
b) Why is NO considered a catalyst not an intermediate? What is the reactive intermediate?
c) If NO2 doesn’t accumulate during the reaction can the proposed mechanism still be valid? If you think it is
explain why? (hint: Think about the relative rates of the reactions.)
3) The activation energy of a certain reaction is 65.7 kJ/mol. How many times faster does the reaction occur at
50oC than 0oC?
4) The gas phase decomposition of SO2Cl2, SO2Cl2 → SO2 + Cl2, is first order in respect to SO2Cl2.
a) At 600oC the half life for this process is 2.3 x 105s. What is the rate constant at this temperature?
b) At 320oC the rate constant is 2.2 x 10-5s-1. What is the half life at this temperature?