Chapter 13 – Chemical Kinetics
74.
The activation energy for the reaction O + O3 → 2O2 is 25 kJ/mol, and the enthalpy change is H = –388 kJ/mol. What is the
activation energy for the decomposition of O2 by the reverse reaction?
Chapter 13 – Chemical Kinetics
75.
For the chemical reaction system described by the diagram below, which statement is true?
Chapter 13 – Chemical Kinetics
76. An increase in the temperature of the reactants causes an increase in the rate of reaction.
The best explanation for this behavior is that as the temperature increases,
Chapter 13 – Chemical Kinetics
77.
For the chemical reaction system described by the diagram below, which statement is true?
If the Ea for the forward reaction is 25 kJ/mol and the enthalpy of reaction is –95 kJ/mol, what is Ea for the reverse reaction?
Chapter 13 – Chemical Kinetics
78.
According to the collision theory, all collisions do not lead to reaction. Which choice gives both reasons why not all
collisions between reactant molecules lead to reaction?
1. The total energy of two colliding molecules is less than some minimum amount of energy.
2. Molecules cannot react with each other unless a catalyst is present.
3. Molecules that are improperly oriented during collision will not react.
4. Solids cannot react with gases.
79. When the concentrations of reactant molecules are increased, the rate of reaction
increases. The best explanation for this phenomenon is that as the reactant concentration
increases,
Chapter 13 – Chemical Kinetics
80.
The following mechanism has been suggested for the reaction:
Identify all intermediates included in this mechanism.
Chapter 13 – Chemical Kinetics
81.
The following mechanism has been suggested for the reaction:
Identify the rate law that is consistent with this mechanism.
Chapter 13 – Chemical Kinetics
82.
The following mechanism has been suggested for the reaction:
Identify the molecularity of the rate determining step.
Chapter 13 – Chemical Kinetics
83.
The following reaction in aqueous solution was found to be first order in [OH–], first order in [C2H5Br], and inverse first
order in Br–.
C2H5Br + OH– → C2H5OH + Br–
Which one of the following mechanisms is consistent with the observed reaction order?
Chapter 13 – Chemical Kinetics
84.
The rate law for the reaction 2NO2 + O3 → N2O5 + O2 is rate = k[NO2][O3]. Which one of the following mechanisms is
consistent with this rate law?
Chapter 13 – Chemical Kinetics
85.
For the reaction X2 + Y + Z → XY + XZ, it is found that the rate equation is rate = k [X2][Y]. Why does the concentration of
Z have no effect on the rate?
Chapter 13 – Chemical Kinetics
86.
The gas phase reaction of nitrogen dioxide and carbon monoxide was found experimentally to be second-order with respect
to NO2, and zero-order with respect to CO below 25C.
NO2 + CO → NO + CO2
Which one of the following mechanisms is consistent with the observed reaction order?
Chapter 13 – Chemical Kinetics
87. Which of the following elementary steps is bimolecular?
Chapter 13 – Chemical Kinetics
88. Which of the following elementary steps is termolecular?
Chapter 13 – Chemical Kinetics
89. Which of the following statements is false?
90. Complete the following statement: A catalyst
Chapter 13 – Chemical Kinetics
91.
With respect to the figure below, which choice correctly identifies all the numbered positions?
Chapter 13 – Chemical Kinetics
92. The activation energy of a certain uncatalyzed reaction is 64 kJ/mol. In the presence of a
catalyst, the Ea is 55 kJ/mol. How many times faster is the catalyzed than the uncatalyzed
reaction at 400C? Assume that the frequency factor remains the same.
93.
Nitrous oxide (N2O) decomposes at 600C according to the balanced equation
2N2O(g) → 2N2(g) + O2(g)
A reaction mechanism involving three steps is shown below. Identify all of the catalysts in the following mechanism.
Cl2(g) → 2Cl(g)
N2O(g) + Cl(g) → N2(g) + ClO(g) (occurs twice)
ClO(g) + ClO(g) → Cl2(g) + O2(g)
Chapter 13 – Chemical Kinetics
94.
The peroxodisulfate ion can oxidize iodide ions to iodine according to the balanced equation
S2O82– + 2I – → 2SO42– + I2.
The reaction is catalyzed by certain chemical species. Identify the catalyst in the following mechanism:
step 1: Fe3+ + 2I – → Fe2+ + I2
step 2: S2O82– + Fe2+ → 2SO42– + Fe3+
95. For the reaction whose rate law is rate = k[X], a plot of which of the following is a straight
line?
Chapter 13 – Chemical Kinetics
96.
At a particular temperature the first-order gas-phase reaction 2N2O5 → 2N2O4 + O2 has a half-life for the disappearance of
dinitrogen pentoxide of 3240 s. If 1.00 atm of N2O5 is introduced into an evacuated 5.00 L flask, what will be the total
pressure of the gases in the flask after 1.50 hours?
97.
At a particular temperature the first-order gas-phase reaction N2O5 → 2NO2 + 1/2O2 has a half-life for the disappearance of
dinitrogen pentoxide of 5130 s. Suppose 0.450 atm of N2O5 is introduced into an evacuated 2.00 L flask. What will be the
total gas pressure inside the flask after 3.00 hours?