5 Written questions
5 Matching questions
- A plot of ln [C] versus time is linear for the reaction C → D. What is the kinetic order of the reaction?
e. negative one
- The rate constant for a first-order reaction is 0.58 s−1 at 25°C. At what temperature would the rate constant have a value of 0.75 s−1? The activation energy is 84 kJ/mol and the universal gas constant = 8.314 J/mol•K.
c. 298 K
d. 301 K
e. 310 K
- Consider a chemical reaction involving compounds A and B, which is found to be first order in A and second order in B. At what rate will the reaction occur in experiment 2?
Experiment Rate (M•s−1) Initial [A] Initial [B]
1 0.10 1.0 M 0.20 M
2 ? 2.0 M 0.60 M
a. 1.2 M•s−1
b. 0.20 M•s−1
c. 0.60 M•s−1
d. 1.8 M•s−1
e. 0.36 M•s−1
- The decomposition of dinitrogen pentoxide obeys the rate-law expression rate = 0.080 min−1[N2O5]. If the initial concentration of N2O5 is 0.30 M, what is the concentration after 2.6 minutes?
N2O5 → N2O3 + O2
a. 0.38 M
b. 0.028 M
c. 0.24 M
d. 0.13 M
e. 0.32 M
- Which of the following statements concerning graphical methods for determining reaction order is false?
a. For a first-order reaction the plot of ln[A] vs. time gives a straight line.
b. For a first-order reaction the slope of the straight-line graph equals −ak.
c. For a second-order reaction the plot of [A]2 vs. time gives a straight line.
d. For a first-order reaction the intercept of the straight-line graph equals ln [A]0.
e. For a zero-order reaction the plot of [A] vs. time gives a straight line.
- a b. first
- b c. 0.24 M
- c c. For a second-order reaction the plot of [A]2 vs. time gives a straight line.
- d b. 300°K
- e d. 1.8 M•s−1
5 Multiple choice questions
- b. The rate is reduced by 3/4.
- b. 0.00648 M
- c. an equation in which reaction rate is equal to a mathematical expression involving, or related to, concentrations of reactants involved in the rate-determining step
- d. 2SO2(g) + O2(g) → 2SO3(g)
- a. 1.87 × 104 s−1
5 True/False questions
For a certain third-order reaction with the general form aA → products, the rate is 0.36 M·s−1 when the concentration of the reactant is 0.35 mol/L. What is the rate constant for this reaction?
a. 0.042 M−2⋅s−1
b. 8.4 M−2⋅s−1
c. 0.36 M−2⋅s−1
d. 0.34 M−2⋅s−1
e. 24 M−2⋅s−1 → e. 48 kJ/mol
The reaction, A + 2B → B2 + A, proceeds by the following mechanism: (A is a catalyst.)
A + B → AB (slow)
AB + B → B2 + A (fast)
What is the rate law expression for this reaction?
a. Rate = k[A]
b. Rate = k[B]
c. Rate = k[A][B]
d. Rate = k[A][B]2
e. Rate = k[A]2[B] → a. M−1•min−1
At 300 K the reaction below obeys the rate law Rate = k[NOCl]2 where k = 2.8 × 10−5 M−1•s−1.
2NOCl → 2NO + Cl2
Suppose 1.0 mole of NOCl is introduced into a 2.0-liter container at 300 K. Evaluate the half-life of the reaction.
a. 2.6 × 103 seconds
b. 3.6 × 104 seconds
c. 2.4 × 104 seconds
d. 1.1 × 103 seconds
e. 4.0 × 104 seconds → b. 3.6 × 104 seconds
A reaction mechanism will usually be
a. the only possible explanation for the reaction.
b. difficult to verify experimentally.
c. generally obvious from the balanced chemical equation.
d. obvious from a consideration of the balanced chemical equation.
e. obvious from a consideration of the reaction rate data. → a. M−1•min−1
Of the following questions, which ones are thermodynamic rather than kinetic concepts?
I. Can substances react when they are put together?
II. If a reaction occurs, how fast will it occur?
III. What is the mechanism by which the reaction occurs?
IV. If substances react, what energy changes are associated with the reaction?
a. I and III
b. II and IV
c. I and IV
d. II and III
e. I, III, and IV → c. I and IV