Chemistry 107 Exam 7-9 Good Luck!

1. Determine the wavelength (in nm) of an X-ray with a frequency of 4 1. Determine the wavelength (in nm) of an X-ray with a frequency of 4.2 x 1018 Hz. 7.1 x 10–11 7.1 x 10–2 1.3 x 1027 1.4 x 1010 7.1 x 10–18 Answer: b Copyright © 2011 Pearson Education, Inc. 2

2. A major league pitcher throws a 148. 8 g baseball at a speed of 92 2. A major league pitcher throws a 148.8 g baseball at a speed of 92.5 mph (41.4 m/s). What is the de Broglie wavelength of the baseball in meters? 4.81 x 10–38 4.81 x 10– 41 1.08 x 10– 34 1.08 x 10– 37 1.08 x 10– 40 Answer: c Copyright © 2011 Pearson Education, Inc. 3

3. An electron in a hydrogen atom in the n = 6 energy level emits 109 3. An electron in a hydrogen atom in the n = 6 energy level emits 109.4 kJ/ mol of energy in a transition to a lower energy level. To what energy level does the electron fall? 1 2 3 4 5 Answer: c Copyright © 2011 Pearson Education, Inc. 4

4. Which of the following transitions for an electron in a hydrogen atom would release the largest quantum of energy? n = 3 → n = 1 n = 4 → n = 3 n = 1 → n = 4 n = 2 → n = 1 Answer: a Copyright © 2011 Pearson Education, Inc. 5

5. Which of the following is NOT an allowed set of quantum numbers? n = 4 l = 3 ml = 3 n = 1 l = 0 ml = 0 n = 5 l = 4 ml = – 2 n = 2 l = 1 ml = 0 n = 3 l = 3 ml = – 2 Answer: e Copyright © 2011 Pearson Education, Inc. 6

6. What is the frequency (Hz) of a infrared light that emits 24 6. What is the frequency (Hz) of a infrared light that emits 24.5 kJ/ mol of energy? 3.70x1034 6.14x1013 4.92x1019 8.17x10–8 2.70x10–35 Answer: b Copyright © 2011 Pearson Education, Inc. 7

7. Ultraviolet light emits a total of 2 7. Ultraviolet light emits a total of 2.5x10–17 J of light at a wavelength of 9.8x10–7 m. How many photons does this correspond to? 1 10 25 100 125 Answer: e Copyright © 2011 Pearson Education, Inc. 8

8. Determine the wavelength (nm) of light absorbed when an electron in a hydrogen atom transitions from the n = 3 to the n = 5 energy level. 434 nm 656 nm 684 nm 780 nm 1280 nm Answer: e Copyright © 2011 Pearson Education, Inc. 9

9. The de Broglie wavelength of a 455 kg car is found to be 5 9. The de Broglie wavelength of a 455 kg car is found to be 5.43x10–38 nm. Calculate the speed (m/ s) of the car. 26.8 m/ s 37.3 m/ s 2.68x10–8 m/ s 3.73x107 m/ s 3.00x108 m/ s Answer: a Copyright © 2011 Pearson Education, Inc. 10

10. Which orbital is described by the following set of quantum numbers 10. Which orbital is described by the following set of quantum numbers? n = 3 l = 1 ml = –1 1s 2s 3s 3p 3d Answer: c Copyright © 2011 Pearson Education, Inc. 11

11. What is the ground state electron configuration for Mo? Mo: [Kr]5s24d4 Mo: [Kr]5s04d6 Mo: [Ar]4s23d4 Mo: [Ar]4s13d5 Mo: [Kr]5s14d5 Answer: e Copyright © 2011 Pearson Education, Inc. 12

12. Which of the following correctly illustrates the valence electron configuration of sulfur? b) c) Answer: a d) Copyright © 2011 Pearson Education, Inc. 13

a) Ge b) Te c) Sn d) Se e) Sb 13. Which element’s 4+ ion would have the following electron configuration? [Kr]4d10 a) Ge b) Te c) Sn d) Se e) Sb Copyright © 2011 Pearson Education, Inc. 14

14. Consider the following isoelectronic series: Cl– Ar K+ Ca2+ Which particle is the largest? a) Cl– b) Ar c) K+ d) Ca2+ e) All particles are the same size. Answer: a Copyright © 2011 Pearson Education, Inc. 15

15. Consider the following successive ionization energies (kJ/mol): IE1 IE2 IE3 IE4 IE5 IE6 IE7 1012 1900 2910 4960 6270 22,200 26,345 Which element in period three would most likely show this trend in ionization energies? a) Mg b) Al c) Si d) P e)S Answer: d Copyright © 2011 Pearson Education, Inc. 16

16. What is the ground state electron configuration for V? V: [Kr]4s33d2 V: [Kr]4s24d3 V: [Ar]4s23d3 V: [Ar]3d3 Answer: c Copyright © 2011 Pearson Education, Inc. 17

a) Rb b) Sr c) Cs d) Ba e) Cl 17. Which element is the largest? a) Rb b) Sr c) Cs d) Ba e) Cl Answer: c Copyright © 2011 Pearson Education, Inc. 18

a) Sn b) Sn2+ c) Sn4+ d) Sn2+ and Sn4+ e) All are paramagnetic 18. Which of the following is diamagnetic? a) Sn b) Sn2+ c) Sn4+ d) Sn2+ and Sn4+ e) All are paramagnetic Answer: d Copyright © 2011 Pearson Education, Inc. 19

19. Which element is the most non-metallic? a) K b) Ca c) Mg d) O e) F Answer: e Copyright © 2011 Pearson Education, Inc. 20

20. How many valence electrons does an atom of Sulfur possess? a. 2 b. 3 c. 4 d. 5 e. 6 Answer: e Copyright © 2011 Pearson Education, Inc. 21

21. Which element has the greatest effective nuclear charge? a. O b. F c. S d. Cl e. P Answer: b Copyright © 2011 Pearson Education, Inc. 22

22. Which of the following sets gives the correct formal charges for the elements in the Lewis structure below? S: –2 C: –4 N: –3 S: +6 C: +4 N: +5 S: –2 C: +4 N: –3 S: +1 C: 0 N: –1 S: 0 C: 0 N: –1 Answer: e Copyright © 2011 Pearson Education, Inc. 23

23. Rank the following in order of increasing bond polarity: H─F 23. Rank the following in order of increasing bond polarity: H─F H─Br F─F Na─Cl H─F < H─Br < F─F < Na─Cl F─F < H─F < H─Br < Na─Cl H─Br < H─F < F─F < Na─Cl F─F < H─Br < H─F < Na─Cl Na─Cl < H─F < H─Br < F─F Answer: d Copyright © 2011 Pearson Education, Inc. 24

24. Determine the formal charge of chlorine in the most stable Lewis structure for ClO2–. –2 –1 +1 +2 Answer: c Copyright © 2011 Pearson Education, Inc. 25

25. Which of the following compounds has ionic bonding? NO2 Al CaCO3 Answer: e Copyright © 2011 Pearson Education, Inc. 26

26. Use average bond energies to determine ΔHrxn for the burning of H2 26. Use average bond energies to determine ΔHrxn for the burning of H2. H2(g) + ½ O2(g) → H2O(g) 6 kJ 470 kJ –243 kJ –350 kJ –421 kJ Bond Bond Energy (kJ/mol) H─H 436 O═O 498 O─O 142 O─H 464 Answer: c Copyright © 2011 Pearson Education, Inc. 27

27. Estimate the enthalpy change for the combustion of methanol, using bond energies. -3454 kJ 2652 kJ -1426 kJ 126 kJ -802 kJ Answer: e Copyright © 2011 Pearson Education, Inc.

28. Draw the Lewis structure for NO3– 28. Draw the Lewis structure for NO3– . How many equivalent resonance structures can be drawn? 1 2 3 4 5 Answer: c Copyright © 2011 Pearson Education, Inc. 29

29. Draw the best Lewis structure for Ca(OH)2 29. Draw the best Lewis structure for Ca(OH)2. How many lone pairs of electrons are on Ca? 1 2 3 4 Answer: d Copyright © 2011 Pearson Education, Inc. 30

The Answers 1. B 2. C 3. C 4. A 5. E 6. B 7. E 8. E 9. A 10. D 11. E