Name ____________________________________________________ Date _______________ Period ___
Homework
Chapter 14: Chemical Kinetics
Exercises: Sections 14.3: Change of Rate with Time - Rate Laws
1.
(a) What is the difference between a rate law and the rate constant?
(b) What is the difference between the reaction order for a specific reactant and the overall reaction
order?
(c) What are the units of the rate constant for a reaction in solution that has an overall reaction order of
two?
2. The decomposition of N2O5 in carbon tetrachloride proceeds as follows:
2 N2O5 → 4 NO2 + O2.
The rate law is first order in N2O5. At 64oC the rate constant is 4.82 x 10 – 3 s– 1.
(a) Write the rate law for the reaction.
(b) What is the rate of reaction when [N2O5] = 0.0240 M?
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2. Continued:
(c) What happens to the rate when the concentration of N2O5 is doubled to 0.0480 M?
3. The reaction between ethyl bromide, C2H5Br, and hydroxide ion in ethyl alcohol at 330 K,
C2H5Br(aq) + OH– (aq) → C2H5OH(l) + Br – (aq)
is first order each in ethyl bromide and hydroxide ion. When [C2H5Br] is 0.0477 M and [OH¯] is
0.100 M, the rate of disappearance of ethyl bromide is 1.7 x 10 – 7 M/ s.
a) What is the value of the rate constant?
(b) What are the units of the rate constant? ____________________
4. The following data were measured for the reaction BF3(g) + NH3(g) →
F3BNH3(g):
Initial Rate
Experiment
1
2
3
4
5
[BF3](M)
[NH3](M)
(M/ s)
0.250
0.250
0.200
0.350
0.175
0.250
0.125
0.100
0.100
0.100
0.2130
0.1065
0.0682
0.1193
0.0596
(a) What is the rate law for the reaction?
(b) What is the overall order of the reaction?
(c) What is the value of the rate constant for the reaction? Follow ALL math work rules!
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5. The iodide ion reacts with hypochlorite ion (the active ingredient in chlorine bleaches) in the following way:
OCl – + I – → OI – + Cl –
This rapid reaction gives the following rate data:
[OCl – ], M
[I – ] , M
Rate, M/s
1.5 x 10 – 3
1.5 x 10 – 3
1.36 x 10 – 4
3.0 x 10 – 3
1.5 x 10 – 3
2.72 x 10 – 4
1.5 x 10 – 3
3.0 x 10 – 3
2.72 x 10 –4
(a) Write the rate law for this reaction:
(b) Calculate the rate constant. Follow ALL math work rules!
(c) Calculate the rate when [OCl – ], = 2.0 x 10 – 3 M and [I1 – 1] = 5.0 x 10 – 4 M. Follow ALL math work rules!
6. Consider the gas-phase reaction between nitric oxide and bromine at 273oC:
2 NO (g) + Br2(g) → 2 NOBr (g)
The following data for the initial rate of appearance of NOBr were obtained:
Experiment
[NO] (M)
[Br2] (M)
Initial Rate (M/s)
1
0.10
0.20
24
2
0.25
0.20
150
3
0.10
0.50
60
4
0.35
0.50
735
(a) Determine the rate law.
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6. Continued:
(b) Calculate the average value of the rate constant for the appearance of NOBr from the four data sets.
Follow ALL math work rules!
(c) How is the rate of appearance of NOBr related to the rate of disappearance of Br2?
(d) What is the rate of disappearance of Br2 when [NO] = 0.075 M and [Br2] = 0.25 M? Follow ALL
math work rules!
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