Chapter 13 – Chemical Kinetics
Chapter 13
Chemical Kinetics
1.
Chlorine dioxide reacts in basic water to form chlorite and chlorate according to the following chemical equation:
2ClO2(aq) + 2OH–(aq) → ClO2–(aq) + ClO3–(aq) + H2O(l)
Under a certain set of conditions, the initial rate of disappearance of chlorine dioxide was determined to be 2.30 x 10–1 M/s.
What is the initial rate of appearance of chlorite ion under those same conditions?
Chapter 13 – Chemical Kinetics
2.
For the reaction BrO3– + 5Br–+ 6H+ → 3Br2 + 3H2O at a particular time, –[BrO3–]/t = 1.5 10–2 M/s. What is –[Br–]/t
at the same instant?
3.
For the following reaction, P(C6H14)/t was found to be –6.2 10–3 atm/s.
C6H14(g) → C6H6(g) + 4H2(g)
Determine P(H2)/t for this reaction at the same time.
Chapter 13 – Chemical Kinetics
4.
For the reaction C6H14(g) → C6H6(g) + 4H2(g), P(H2)/t was found to be 2.5 10–2 atm/s, where P(H2) is the change in
pressure of hydrogen. Determine P(C6H14)/t for this reaction at the same time.
5.
For the hypothetical reaction A + 3B → 2C, the rate of appearance of C given by ([C]/t) may also be expressed as
Chapter 13 – Chemical Kinetics
6.
For the overall chemical reaction shown below, which one of the following statements can be rightly assumed?
2H2S(g) + O2(g) → 2S(s) + 2H2O(l)
7.
The reaction A + 2B → products has been found to have the rate law, rate = k[A] [B]2. While holding the concentration of A
constant, the concentration of B is increased from x to 3x. Predict by what factor the rate of reaction increases.
Chapter 13 – Chemical Kinetics
8.
For the reaction A + 3B → 2C, the rate of disappearance of B given by ([B]/t) may also be expressed as
9.
The reaction A + 2B → products has the rate law, rate = k[A][B]3. If the concentration of B is doubled while that of A is
unchanged, by what factor will the rate of reaction increase?
Chapter 13 – Chemical Kinetics
10.
The reaction A + 2B → products was found to have the rate law, rate = k[A] [B]2. Predict by what factor the rate of reaction
will increase when the concentration of A is doubled and the concentration of B is also doubled.
11.
The reaction A + 2B → products was found to follow the rate law: rate = k[A]2[B]. Predict by what factor the rate of reaction
will increase when the concentration of A is doubled, the concentration of B is tripled, and the temperature remains constant.
Chapter 13 – Chemical Kinetics
12. Concerning the rate law, Rate = k[A][B], what are appropriate units for the rate constant
k?
13. Concerning the rate law, Rate = k[A]0, what are appropriate units for the rate constant k?
Chapter 13 – Chemical Kinetics
14. Concerning the rate law, Rate = k[A]2[B], what are appropriate units for the rate constant
k?
15. Concerning the rate law, Rate = k[A][B][C], what are appropriate units for the rate
constant k?
16. Appropriate units for a first-order rate constant are
Chapter 13 – Chemical Kinetics
17. It takes 42.0 min for the concentration of a reactant in a first-order reaction to drop from
0.45 M to 0.32 M at 25C. How long will it take for the reaction to be 90% complete?
18.
Chlorine dioxide reacts in basic water to form chlorite and chlorate according to the following chemical equation:
2ClO2(aq) + 2OH–(aq) → ClO2–(aq) + ClO3–(aq) + H2O(l)
A kinetic study of this reaction under a certain set of conditions yielded the data below.
Which one of the following is the rate law for this reaction?
Chapter 13 – Chemical Kinetics
19.
Nitric oxide gas (NO) reacts with chlorine gas according to the chemical equation given below.
NO + ½Cl2 → NOCl
The following initial rates of reaction have been measured for the given reagent concentrations.
Which of the following is the rate law (rate equation) for this reaction?
Chapter 13 – Chemical Kinetics
20.
Use the following data to determine the rate law for the reaction shown below.
2NO + H2 → N2O + H2O
Chapter 13 – Chemical Kinetics
21.
The data below were determined for the reaction shown below.
S2O82– + 3I – (aq) → 2SO42– + I3–
The rate law for this reaction must be:
22. At 25C the rate constant for the first-order decomposition of a pesticide solution is 6.40
10–3 min–1. If the starting concentration of pesticide is 0.0314 M, what concentration will
remain after 62.0 min at 25C?
Chapter 13 – Chemical Kinetics
23.
A certain first-order reaction A → B is 25% complete in 42 min at 25C. What is the half-life of the reaction?
24. The half life for a first order reaction is 27 min. How long will it take for 4 half lives to
occur?
Chapter 13 – Chemical Kinetics
25. The half life for a first order reaction is 45 min. What is the rate constant in units of s-1?
26.
The following initial rate data apply to the reaction below.
F2(g) + 2Cl2O(g) → 2FClO2(g) + Cl2(g)
Which of the following is the rate law (rate equation) for this reaction?
Chapter 13 – Chemical Kinetics
27.
Nitric oxide reacts with chlorine to form nitrosyl chloride, NOCl. Use the following data to determine the rate equation for
the reaction.
NO + 1/2Cl2 → NOCl
28.
The first-order decomposition, A → products, has a rate constant of 0.150 s–1. Starting with [A]o = 0.350 M, how much time
is required for [A]t = 0.125 M?
Chapter 13 – Chemical Kinetics
29.
A certain reaction, reaction A → products, is first order with respect to A. Starting with [A] = 0.250M, it takes 45 min to
reduce the concentration of A to 0.110M. What is its rate constant for this reaction?
30.
Ammonium ion (NH4+) reacts with nitrite ion (NO2–) to yield nitrogen gas and liquid water. The following initial rates of
reaction have been measured for the given reactant concentrations.
Which of the following is the rate law (rate equation) for this reaction?
Chapter 13 – Chemical Kinetics
31. Appropriate units for a second-order rate constant are
32.
The isomerization of cyclopropane to form propene is a first-order reaction.
At 760 K, 15% of a sample of cyclopropane changes to propene in 6.8 min. What is the half-life of cyclopropane at 760 K?
Chapter 13 – Chemical Kinetics
33.
The isomerization of cyclopropane to form propene is a first-order reaction.
At 760 K, 85% of a sample of cyclopropane changes to propene in 79.0 min. Determine the rate constant for this reaction at
760 K.
Chapter 13 – Chemical Kinetics
34.
The isomerization of cyclopropane to propene follows first-order kinetics.
At 700 K, the rate constant for this reaction is 6.2 10–4 min–1. How many minutes are required for 10.0% of a sample of
cyclopropane to isomerize to propene?
Chapter 13 – Chemical Kinetics
35.
At 700 K, the rate constant for the following reaction is 6.2 10–4 min–1.
How many minutes are required for 20% of a sample of cyclopropane to isomerize to propene?
36. A city’s water supply is contaminated with a toxin at a concentration of 0.63 mg/L.
Fortunately, this toxin decomposes to a safe mixture of products by first-order kinetics with a
rate constant of 0.27 day–1. How long will it take for half of the toxin to decompose?