5 Written questions
5 Matching questions
- In the following reaction, = −0.89 mol/L•s. What is the value of the rate of the reaction at this time?
A + 3B → AB3
a. 0.30 mol/L•s
b. 0.89 mol/L•s
c. −0.30 mol/L•s
d. 2.67 mol/L•s
e. 0.22 mol/L•s
- The rate constant for the second order reaction below is 2.79 L/mol •min at 48°C. If the initial concentration of NO2 is 1.05 M , what is the half-life?
2NO2 → N2O4
a. 20.5 s
b. 10.3 s
c. 0.341 min
d. 176 s
e. 14.9 s
- Which of the following statements about reaction mechanisms is false?
a. A reaction can have more than one possible mechanism.
b. A reaction mechanism must be consistent with the experimentally observed rate law.
c. The slowest step in the reaction mechanism is called the rate-determining step.
d. Reaction mechanisms involve complex reaction steps.
e. Reaction mechanisms are difficult to prove.
- Calculate the activation energy of a reaction if its rate constant is 2.8 × 106 s−1 at 24°C and 1.5 × 107 s−1 at 48°C.
a. 26 kJ/mol
b. 80. kJ/mol
c. 55 kJ/mol
d. 67 J/mol
e. 3.51 J/mol
- The oxidation of NO by O3 is first order in each of the reactants, and its rate constant is 1.5 × 107 M−1•s−1. If the concentrations of NO and O3 are each 5.0 × 10−7 M, what is the rate of oxidation of NO in M•s−1?
a. 3.8 × 10−6
b. 2.5 × 10−14
c. 7.5 × 10−7
- a d. Reaction mechanisms involve complex reaction steps.
- b a. 0.30 mol/L•s
- c c. 55 kJ/mol
- d a. 3.8 × 10−6
- e b. 10.3 s
5 Multiple choice questions
- d. 18
- a. decrease by 3/4
- e. 6.4 × 10−3 M•s−1
- a. 21 min
- c. is third.
5 True/False questions
The rate constant for a first-order reaction is 1.4 × 10-2 s-1 at 716 K and 5.5 × 10-2 s-1 at 864 K. What is the activation energy?
a. 27 kJ/mol
b. 21 kJ/mol
c. 47 kJ/mol
d. 5700 kJ/mol
e. 48 kJ/mol → a. 1.87 × 104 s−1
Which of the following statements about catalysts are false?
a. A catalyst lowers the activation energy.
b. A catalyst can make a nonspontaneous reaction spontaneous.
c. A catalyst speeds up both the forward and reverse reaction.
d. A catalyst speeds up the rate of reaction.
e. Catalyst are often transition metals and transition metal oxides. → d. Reaction mechanisms involve complex reaction steps.
Which term is incorrectly matched with its description?
a. Activation Energy / kinetic energy required for reaction to occur
b. Transition State / short-lived high-energy intermediate state
c. Effective Collision / molecular collision resulting in a reaction
d. Net energy change of the reaction / Ea, forward − Ea, reverse
e. Endothermic Reaction / reaction having Ea, reverse > Ea, forward → e. The Grand Canyon was created by dissolution by water over millions of years.
Cyclopropane rearranges to form propene in a reaction that is first order. If the rate constant is 2.74 × 10−3 s−1, how long would it take for 85.6% of the cyclopropane to rearrange if the initial concentration was 0.460 M?
a. 51.0 s
b. 62.0 s
c. 707 s
d. 2.74 × 10−3 s
e. 3.83 × 10−4 s → d. 0.491
The gas phase reaction below obeys the rate-law expression rate = k[SO2Cl2]. At 593 K the specific rate constant is 2.2 × 10−5 s−1. A 2.0-g sample of SO2Cl2 is introduced into a closed 4.0-L container.
SO2Cl2 → SO2 + Cl2
How much time must pass in order to reduce the amount of SO2Cl2 present to 1.8 grams?
a. 7.4 × 103 seconds
b. 2.1 × 102 seconds
c. 3.5 × 102 seconds
d. 4.8 × 103 seconds
e. 5.8 × 104 seconds → b. 3.6 × 104 seconds