 | Sample Lab Questions Investigation #20:
"The Kinetics of the Decomposition
of Hydrogen Peroxide"
|
Click HERE for an overview of Investigation 20, compliments of Mr. Alex Redd.
These questions have been taken from lab quizzes given in previous years.
Some of the answers are listed at the end.
Note: The subscripts and superscripts may not appear as such. It depends upon your web browser.
- 1.
- (1pt) Define catalyst.
- 2.
- (1pt) What role does KI play in the decomposition of hydrogen peroxide in INV #22?
- 3.
- (2 pts) The chemists working at a chemical company have an idea for a new reaction to produce a valuable product. They determine that
G is negative for this reaction. Should they recommend to the board of directors of the company that a new plant be built to use this reaction to produce the product? Why or why not?
- 4.
- (4pts) Use the table below to answer the following questions. Rate = k[H2O2]n[I-]m
| Vol. 0.15 M KI | Vol. 0.090 M H2O2 | Vol. H2O | Rate (mL O2/sec) |
|---|
| Trial 1 | 10 mL | 20 mL | 20 mL | 20 mL/sec |
|---|
| Trial 2 | 10 mL | 10 mL | 30 mL | 10 mL/sec |
|---|
| Trial 3 | 20 mL | 10 mL | 20 mL | 20 mL/sec |
|---|
- a. Calculate the initial concentrations of KI and H2O2 in the solution for each trial before any reaction starts.
- b. Determine the values of n and m.
- c. Calculate k (include its units).
- 5.
- a.(1pt) Complete and balance the following equation for the decomposition of H2O2:
H2O2
H2O + _______
- b.(1pt) Calculate the number of moles of O2 produced from the decomposition reaction, when 30.0 mL of 2.50% (w/w) H2O2 is mixed with KI, assuming the H2O2 decomposes completely. (Assume the density of 2.50% H2O2 is 1.00 g/mL.)
- c.(2pts) Calculate the volume this dry O2 would occupy at a pressure of 1.01 atm and 24ｰC. (R = 0.0821 L病tm/mol必)
- 6.
- (3pts) 15.0 mL of O2 saturated with H2O vapor were evolved during the decomposition of peroxide. The lab temperature was 23ｰC and barometric pressure was 763 torr. (Vapor pressure of H2O at 23ｰC = 21.1 torr, R = 0.0821 L病tm瀕ol-1必-1 or 62.4 L付orr瀕ol-1必-1)
- a. Calculate the volume in mL of dry O2 formed under these conditions.
- b. Calculate the number of grams of O2 formed under these conditions.
Answers
| 4. | a. | Trial 1: [KI] = 0.030 M, [H2O2] = 0.036 M
Trial 2: [KI] = 0.030 M, [H2O2] = 0.018 M
Trial 3: [KI] = 0.060 M, [H2O2] = 0.018 M
|
| b. | n=1, m=1 |
| c. | k = 1.9 x 104 mL M-2 sec-1 |
| 5. | b. | 0.0110 mol O2 |
| c. | 0.266 L or 266 mL |
| 6. | a. | 14.6 mL |
| b. | 0.0188 g O2 |
To report any corrections, please e-mail Dr. Wendy Keeney-Kennicutt.