PreAP Chemistry Unit 18 Review Sheet



PreAP Chemistry Unit 18 Review Sheet

Use the following data to answer questions 1-3 for the reaction 4NO2 + O2 → 2N2O5

|Trial |[NO2] |[O2] |Rate (M/s) |

|1 |0.025 |0.011 |3.1 x 10-4 |

|2 |0.025 |0.022 |6.2 x 10-4 |

|3 |0.050 |0.011 |6.2 x 10-4 |

1. Write the rate law expression for the reaction.

2. Calculate the rate constant (including units).

3. Use the rate law expression and calculated value of k to compute the initial rate of formation of N2O5 if the initial concentrations of NO2 and O2 were each 0.030 M.

4. The following initial rate data for the reaction A + B → C were observed. Write the rate law for the reaction.

|Trial |[A] |[B] |Rate (M/s) |

|1 |0.15 |0.15 |3 x 10-4 |

|2 |0.15 |0.33 |3 x 10-4 |

|3 |0.30 |0.33 |1.2 x 10-3 |

5. A reaction has the rate law, rate = k[A][B]2. If the numerical value of k = 2.5 x 10-2 M-2s-1, what is the rate when the concentration of A is 0.20 M and the concentration of B is 0.30 M?

6. The thermal decomposition of ethylene oxide, C2H4O, produces methane and carbon monoxide: C2H4O ↔ CH4 + CO. The following data was collected at 725 K.

|Trial |[C2H4O] |Rate (M/s) |

|1 |0.001412 |3.451 x 10-5 |

|2 |0.002824 |6.902 x 10-5 |

a. Write the rate law for the reaction.

b. Calculate the value of the specific rate constant (including units).

7. Below is data collected for a single reactant equation:

|Time (sec) |[A] | | |

|17 |2.24 | |a. What is the order of the reaction? |

|23 |2.15 | |b. What is the value of the rate constant (with units)? |

|31 |2.04 | |c. What was the initial concentration? |

|39 |1.94 | | |

|47 |1.84 | | |

8. Below is data collected for a single reactant equation:

|Time (min) |[A] | | |

|5 |0.48 | |a. What is the order of the reaction? |

|10 |0.47 | |b. What is the value of the rate constant (with units)? |

|15 |0.46 | |c. What was the initial concentration? |

|20 |0.45 | | |

|25 |0.44 | | |

9. Below is data collected for a single reactant equation:

|Time (sec) |[A] | | |

|45 |0.0118 | |a. What is the order of the reaction? |

|60 |0.0089 | |b. What is the value of the rate constant (with units)? |

|75 |0.0071 | |c. What was the initial concentration? |

|90 |0.0059 | | |

|105 |0.0051 | | |

10. Using the periodic table, write nuclear symbols for the isotopes:

a. lead-208 b. lead-210 c. uranium-235 d. carbon-14

e. helium-5 f. potassium-40 g. lithium-8 h. uranium-238

11. Complete and balance the following equations:

a. [pic] b. [pic] c. [pic] d. [pic]

e. [pic] f. [pic] g. [pic] h. [pic]

12. In a portion of the uranium decay series, lead-214 decays to bismuth-214 by beta emission. The bismuth-214 decays to polonium-214 by beta emission. The polonium-214 decays to lead-210 by alpha emission. Write balanced nuclear equations to represent these three steps.

13. The half-life of zinc-71 is 2.4 minutes. How long will it take for a sample of zinc-71 to decay to 1/16 of its original mass?

14. A radioactive tracer, sodium-24, is used to study circulatory problems. If you start with 5.85 x 1023 atoms, how many atoms will remain after 12.0 days? The half-life of sodium-24 is 4.0 days.

15. some patients with thyroid disorders receive radioactive iodine-131. The half-life of iodine-131 is 8.07 days. If you start with 7.73 x 1012 atoms, how much time will pass before the amount is reduced to 7.55 x 109 atoms?

16. Complete the following nuclear equations. Identify the type of radioactive decay.

a. [pic] b. [pic] c. [pic] d. [pic]

17. Complete the following nuclear equations:

a. [pic] b. [pic] c. [pic] d. [pic]

18. Batteries used in heart pacemakers contain plutonium-238. If your original sample contains 2.57 x 109 atoms of plutonium-238, how much time will pass before the amount is reduced to 5.02 x 106 atoms? The half-life is 27.1 years.

19. Carbon-14 has a half-life of 5730 years and is used for radioactive dating. Assume we started with 2.18 x 1017 atoms of carbon-14 in a wood sample obtained from a wooden beam from an ancient tomb. There are 1.21 x 1017 atoms remaining. How old can we assume the wooden beam to be?

20. Promethium-147 has a half-life of 2.5 years and is used to paint luminous dials. If a sample originally contains 9.72 x 1023 atoms of promethium-147, how many atoms will remain after 10.0 years?

21. What name is used to describe synthesized element that have atomic numbers greater than 92?

22. How do scientists refer to natural radiation from rocks, building materials and outer space?

23. What is nuclear fusion?

24. What word is used to describe the splitting of heavy nucleus into two parts?

25. What device is constructed to contain and control a nuclear fission reaction?

Answers:

1. Rate = k[NO2][O2]

2. 1.1 M-1s-1

3. rate = 9.9 x 10-4 M/s

4. Rate = k[A]2

5. 4.5 x10-4 M/s

6. a. Rate = k[C2H4O] b. 0.02444 s-1

7. a. 1st order b. 6.5 x 10-3 s-1 c. 2.5 M

8. a. 0 order b. 0.002 M/min c. 0.49 M

9. a. 2nd order b. 1.865 M-1s-1 c. 1.2416 M

10. a. [pic] b. [pic] c. [pic] d. [pic]

e. [pic] f. [pic] g. [pic] h. [pic]

11. a. [pic] b. [pic] c. [pic] d. [pic]

e. [pic] f. [pic] g. [pic] h.[pic]

12. [pic], [pic], [pic]

13. 9.6 minutes

14. 7.3 x 1022 atoms

15. 80.7 days

16. a. [pic], beta decay b. [pic], beta decay

c. [pic], alpha decay d. [pic], positron emission

17. a. [pic] b. [pic] c. [pic] d. [pic]

18. 244 years

19. 4860 years

20. 6.08 x 1022 atoms

21. transuranium elements

22. back ground radiation

23. two or more small nuclei combine to form one larger nucleus

24. fission

25. nuclear reactor

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