Workshop CHE 168
Problem Set #4
1.
(a) How is the rate of disappearance of ozone related to the rate of appearance of oxygen in the following reaction:
2 O3 (g) ® 3 O2 (g)?
(b) If the rate of appearance of oxygen is 6.0 x 10-5 M/s, what is the rate of disappearance of ozone?
2. The rate of decomposition of N2O5 proceeds according to the equation2 N2O5 (g) ® 4 NO2 (g) + O2 (g)
If the rate of decompostion of N2O5 is 4.2 x 10-7 M/s, what is the rate of appearance of:
(a) NO2
(b) O2
3. The initial rate of a reaction, A + B ® C, was measured for several different starting (initial) concentrations of A and B with the following results:
Experiment No. [A], M [B], M +Rate(C), M/s 1. 0.100 0.100 4.0 x 10-5 2. 0.100 0.200 4.0 x 10-5 3. 0.200 0.100 16.0 x 10-5 Using these data, determine
(a) the rate law for the reaction
(b) the value of the rate constant (with units!)
(c) the rate of the reaction when [A] = 0.050 M and [B] = 0.100 M.
4. The following data were collected for the rate of disappearance of NO in the reaction2 NO (g) + O2 (g) ® 2 NO2 (g):
Experiment No. [NO], M [O2], M - Rate(NO), M/s 1. 0.0126 0.0125 1.41 x 10-2 2. 0.0252 0.0250 1.13 x 10-2 3. 0.0252 0.0125 5.64 x 10-2 Using these data, determine
(a) the rate law for the reaction
(b) the value of the rate constant (with units!).
5. Consider the gas-phase reaction between nitric oxide and bromine at 273 oC:2 NO (g) + Br2 (g) ® 2 NOBr (g)
The following data for the initial rate of apparance of NOBr were determined:
Experiment No. [NO], M [Br2], M +Rate(NOBr), 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 Using these data, determine
(a) the rate law for the reaction
(b) the value of the rate constant (with units!)
(c) For Experiment No. 3, what is the value of the initial rate of disappearance of Br2?
(d) the rate of the reaction when [NO] = 0.075 M and [Br2] = 0.185 M.
6. The following table shows the rate constants for the rearrangement of methyl isonitrile at various temperatures:
Temperature, oC k, s-1 189.7 2.52 x 10-5 198.9 5.25 x 10-5 230.3 6.30 x 10-4 251.2 3.16 x 10-3 (a) From these data, calculate the activation energy for the reaction.
(b) What is the value of the rate constant at 430.0 oC?
7. The reaction 2 NO (g) + Cl2 (g) ® 2 NOCl (g) obeys the rate law, Rate = k[NO]2[Cl2]. The following mechanism has been proposed for this reaction:NO (g) + Cl2 (g) ® NOCl2 (g)
NOCl2 (g) + NO (g) ® 2 NOCl (g)
(a) What would the rate law be if the first step were rate determining?
(b) Based on the observed rate law, what can we conclude about the relative rates of the two steps?