5 Written questions
5 Matching questions
- Which statement concerning a possible mechanism for a reaction is false?
a. A possible mechanism must be consistent with the experimental data.
b. Each elementary step is represented by a balanced equation.
c. The elementary steps must add to give the equation for the overall reaction.
d. The speed of the slow step limits the rate at which the overall reaction occurs.
e. The slow step will only include reactants listed in the overall chemical equation.
- #126 go to graph
- The second order reaction below has a rate constant of 5.76 M−1•min−1 at 1600 K.
2CH4 → C2H2 + 3H2
How long would it take for the concentration of CH4 to be reduced from 0.89 M to 5.25 × 10−4 M?
a. 165 hrs
b. 0.15 hrs
c. 2.75 hrs
d. 5.51 hrs
e. 9.27 hrs
- 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
- #128 graph
- a go to graph
- b c. 2.75 hrs
- c c. 0.24 M
- d e. The slow step will only include reactants listed in the overall chemical equation.
- e graph
5 Multiple choice questions
- e. The larger its value, the slower the reaction rate.
- d. 1 and 2
- c. rate = k1[A]2
- a. 3.10 hrs
- d. 525
5 True/False questions
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. → d. Reaction mechanisms involve complex reaction steps.
The reaction of ICl with hydrogen : 2 ICl + H2 → I2 + 2 HCl
is first order in ICl and second order in H2. In an experiment to determine the rate law, the rate constant was determined to be 2.24 M-2s-1. Using this value for the rate constant, the rate of the reaction when [ICl] = 0.314M and [H2] = 0.179M would be:
a. 1.26 x 10-3 Ms-1
b. 2.25 x 10-2 Ms-1
c. 3.95 x 10-2 Ms-1
d. 2.23 x 102 Ms-1
e. 2.52 x 10-1 Ms-1 → b. 2.25 x 10-2 Ms-1
Evaluate the specific rate constant for the reaction at the temperature for which the data were obtained. The rate-law expression is rate = k[A][B]2.
A + B → C
Experiment Initial [A] Initial [B] Initial Rate of Formation of C
1 0.10 M 0.10 M 4.0 × 10−4 M/min
2 0.20 M 0.20 M 3.2 × 10−3 M/min
3 0.10 M 0.20 M 1.6 × 10−3 M/min
a. 1.2 × 10−2 M−2•min−1
b. 3.6 × 10−2 M−2•min−1
c. 4.0 × 10−1 M−2•min−1
d. 6.2 × 10−1 M−2•min−1
e. 7.0 × 10−3 M−2•min−1 → e. 9.0 × 10−2 M−2•s−1
Which of the following is a kinetics concept?
a. free energy
d. reaction mechanism
e. entropy → e. Reactions involving simultaneous trimolecular collisions are very common in gases.
Which statement is incorrect?
a. The reaction rate for a zero-order reaction is independent of concentrations.
b. The specific rate constant for a zero-order reaction is independent of temperature.
c. The half-life for a first-order reaction is independent of initial concentrations.
d. The rate law expression relates rate and concentration.
e. The integrated rate equation relates time and concentration. → b. The specific rate constant for a zero-order reaction is independent of temperature.