Advanced Chemistry II
Rate Law Practice Problems
Simple Rate Expressions
Write the simple rate expression for the following reaction in terms of both the disappearance of the reactants
and the appearance of the products:
1. I-(aq) + OCl-(aq)  Cl-(aq) + OI-(aq)
Simple Rate Problems
2. Thiosulfate ion is oxidized by iodine in aqueous solution according to the equation:
2S2O32-(aq) + I2(aq)  S4O62-(aq) + 2I-(aq). If 0.025 moles of thiosulfate is consumed in 0.50 L of solution
per minute, calculate the rate of removal of S2O32- in M/s.
3. N2O5 is an unstable compound that decomposes according to the following equation:
2N2O5  4NO2 + O2. The following data was obtained at 50°C:
[N2O5]
1.00
0.88
0.78
0.69
0.61
0.54
0.48
Time (s) 0
200
400
600
800
1000
1200
a. What is the average rate of N2O5 disappearance in the time interval 200-400 s?
b. What is the average rate of N2O5 disappearance in the time interval 800-1000 s?
0.43
1400
Rate Constant
4. Consider the reaction 2 N2O5  4 NO2 + O2. Using the data below, calculate the rate constant (k). The
reaction is first-order.
[N2O5]
1.00
0.88
0.78
0.69
0.61
0.54
0.48
0.43
Time (s) 0
200
400
600
800
1000
1200
1400
Rate Law
5. Use the following data to determine a) the reaction order of A and B, b) the rate constant (k), and c) the
rate law equation for the reaction that proceeds by the equation 2A + B  C.
Experiment
[A]
[B]
Rate (M/s)
1
0.25
0.10
0.012
2
0.25
0.20
0.048
3
0.50
0.10
0.024
6. The following rate data is for the reaction 2NO + 2H2  N2 + 2H2O. Use the data to calculate a) the
reaction order of NO and H2, b) the rate constant (k), and c) the rate law equation.
Experiment
[NO]
[H2]
Rate (M/s)
1
0.60
0.15
0.076
2
0.60
0.30
0.15
3
0.60
0.60
0.30
4
1.20
0.60
1.21
7. The following experimental data were obtained for the reaction 2A + B  C.
What is the rate law for this reaction?
Experiment
[A]
[B]
Rate (M/s)
1
0.40
0.20
0.0056
2
0.80
0.20
0.0055
3
0.40
0.40
0.0223