CHAPTER 7 PRACTICE TEST QUESTIONS Information that most likely will be on the front cover of your exam: J = kgm2/s2 c = 3.00 x 108 m/s E=hν E=hc/λ h = 6.626 x 10‐34 J•s c = λν λ = h/mu 1/λ = R(1/n12 – 1/n22) ΔE = ‐2.18 x 10‐18 J(z2/nf2 – z2/ni2) Rydberg constant = 1.096776 x 107 m‐1 1. Place the following in order of increasing energy per photon. orange light (λ = 630 nm) violet light (λ = 405 nm) green light (λ = 510 nm) a. green < orange < violet b. violet < green < orange c. orange < green < violet d. green < violet < orange e. orange < violet < green 2. Determine the wavelength (in nm) associated with a photon of energy 5.22 x 10‐22 kJ. a. 346 nm b. 381 nm c. 104 nm d. 262 nm e. 522 nm 3. What is the energy of a photon of green light with a wavelength of 535 nm? a. 3.54 x 10‐40 J b. 1.06 x 10‐22 J c. 3.72 x 10‐19 J d. 3.54 x 10‐31 J e. 3.72 x 10‐28 J 4. How much total energy is emitted from a collection of 0.331 moles of H atoms if each atom is emitting a photon with a frequency of 6.17 x 1014 Hz? a. 4.09 x 10‐19 J b. 3.22 x 10‐40 J c. 6.42 x 10‐17 J d. 2.46 x 105 J e. 8.15 x 104 J 5. Which of the following transitions in a hydrogen atom will emit a photon with the longest wavelength of light? a. n = 3 to n = 4 b. n = 5 to n = 4 c. n = 2 to n = 1 d. n = 2 to n = 5 e. n = 3 to n = 2 6. Which of the following transitions in an H atom would have the highest frequency? a. n = 1 to n = 2 b. n = 2 to n = 4 c. n = 3 to n = 4 d. n = 4 to n = 5 e. n = 3 to n = 6 7. Which of the following transitions are associated with the largest wavelength of photon emitted? a. n = 2 to n = 1 b. n = 6 to n = 5 c. n = 6 to n = 1 d. n = 4 to n = 2 e. n = 5 to n = 2 8. Which of the following statements concerning the hydrogen atom is TRUE? a. A transition from n=1 to any n > 1 requires emission of energy from the atom. b. A transition from n=3 to n=4 involves greater energy than a transition from n=1 to n=2. c. A transition from n=5 to n=3 will emit radiation of longer wavelength than one from n=4 to n=2. d. A transition from n=1 to n=10 corresponds to the ionization energy of the H atom. e. None of the above are true. 9. Which of the following statements is TRUE? a. The highest frequency transition (with Δn=1) in an H atom is from n=1 to n=2. b. All transitions of Δn=1 have the same wavelength in the H atom. c. The transition from n=1 to n=3 has the same ΔE value in the H atom as it would in the He+ ion. d. The transition from n=4 to n=3 represents the absorption of a photon. e. None of the above statements is true. 10. Consider an atom that only contains the 5 energy levels shown below. How many different wavelengths of light could be observed in an emission spectrum for this atom? Hint: This is the same as the number of possible transitions. a. 1 b. 4 c. 5 d. 10 e. 15 11. Which of the following statements concerning the hydrogen atom is TRUE? a. The wavelength of light associated with the transition from n=1 to n=2 is longer than the wavelength of light associated with the transition from n=2 to n=3. b. The frequency of light associated with the transition from n=2 to n=3 is lower than the frequency of light associated with the transition from n=4 to n=5. c. The transition from n=1 to n=5 is called emission. d. The transition from n=3 to n=2 is an exothermic process. e. None of the above statements are true. 12. Determine ΔE for the n = 1 to n = 5 transition in the O7+ ion. a. 2.09 x 10‐18 J b. 1.34 x 10‐16 J c. 6.74 x 108 J d. 1.39 x 10‐17 J e. 1.74 x 10‐18 J 13. Determine the frequency of light associated with the transition from n = 4 to n = 2 in a Be3+ ion. a. 9.87 x 1015 s‐1 b. 4.09 x 10‐19 s‐1 c. 6.17 x 1014 s‐1 d. –6.54 x 1018 s‐1 e. 6.54 x 10‐18 s‐1 14. Determine the initial n value of a transition in a Li2+ ion if ΔE for the transition is –3.68 x 10‐18 J and the transition ends at n = 2. a. 5 b. 4 c. 3 d. 2 e. 1 15. Determine the amount of energy required to ionize 1.50 moles of H atoms if the ionization of hydrogen requires a photon with a wavelength of 91.2 nm. a. 3.94 x 10‐18 J b. 2.74 x 107 J c. 1.31 x 106 J d. 2.18 x 10‐18 J e. 1.97 x 106 J 16. The velocity of an electron emitted from a metallic surface by a photon is 2.2 x 106m/s. What is the wavelength of the electron if it weighs 9.11 x 10‐28 g? a. 1.5 x 10‐27 m b. 3.3 x 10‐10 m c. 1.4 x 10‐9 m d. 6.6 x 10‐7 m e. 3.3 x 10‐13 m 17. Which of the following objects would you estimate to have the shortest deBroglie wavelength if they are all traveling at the same speed? a. baseball b. marble c. bowling ball d. electron e. pebble 18. Which of the following objects is moving the slowest if they all have the same deBroglie wavelength? a. electron b. H atom c. Ar atom d. baseball e. They are all moving the same speed. 19. Which of the following processes is endothermic? A) Combustion of natural gas. B) Condensation of water. C) Transition of an electron in a hydrogen atom from n=4 to n=2. D) Vaporization of ethanol. E) None of the above are endothermic. 20. Which of the following processes is exothermic? a. CH3OH (s) → CH3OH (g) b. Zr (s) + O2 (g) → ZrO2 (s) c. N2 (g) + O2 (g) + 180.6 kJ → 2NO (g) d. An electron undergoing a transition in an H atom from n = 1 to n = 2 e. None of the above. 21. Which of the following processes are exothermic? a. liquid → solid b. light absorption by an atom c. the temperature of a water sample increases due to its warmer surroundings d. heat of vaporization e. None of the above are exothermic processes. 22. Which of the following processes is endothermic? a. The freezing of water. b. The emission of a photon from an excited atom. c. The combustion of methane (CH4). d. The reaction of H2 and O2 to form water vapor (balloon demos in class). e. None of the above processes are endothermic. 23. Which of the following processes is exothermic? a. Thermite reaction (class demo); 2Al(s)+Fe2O3(s) → 2Fe(s)+Al2O3(s) b. Freezing liquid water to make an ice cube. c. The transition of an electron from n=3 to n=1 in a hydrogen atom. d. Zr(s) + O2(g) → ZrO2(s) + 1099 kJ e. All of the above are exothermic processes. 24. Which of the following processes is ENDOTHERMIC? a. H2O (l) → H2O (s) b. A hydrogen atom undergoing a transition from n = 2 to n = 1 c. C2H5OH (l) + 3O2 (g) → 2CO2 (g) + 3H2O (l) d. C2H5OH (s) → C2H5OH (g) e. None of the above. EXTRA CHAPTER 7 PRACTICE TEST QUESTIONS Information that most likely will be on the front cover of your exam: J = kgm2/s2 c = 3.00 x 108 m/s E=hν E=hc/λ h = 6.626 x 10‐34 J•s c = λν λ = h/mu 1/λ = R(1/n12 – 1/n22) ΔE = ‐2.18 x 10‐18 J(z2/nf2 – z2/ni2) Rydberg constant = 1.096776 x 107 m‐1 1. Which of the following statements is TRUE? a. An orbital describes the exact path of an electron around a nucleus. b. It is possible to determine the exact location and trajectory of an electron at any given point in time. c. It is possible to calculate the wavelength of a moving electron. d. None of these statements is true. 2. Determine the wavelength (in nm) associated with a photon of energy 5.22 x 10‐22 kJ. a. 346 nm b. 381 nm c. 104 nm d. 262 nm e. 522 nm 3. How fast would a marble (mass = 5.00 g) have to travel to have a wavelength of 411 nm (equivalent to violet light)? a. 3.11 x 1024 m/s b. 3.22 x 10‐25 m/s c. 3.00 x 108 m/s d. 3.22 x 10‐37 m/s e. 4.11 x 10‐24 m/s 4. Covalent bonds in a molecule absorb radiation in the IR region and vibrate at certain frequencies. The HCl bond has a frequency of 8.652 x 1013 s‐1. What wavelength corresponds to this frequency? a. 2884 nm b. 3467 nm c. 573 nm d. 335 nm e. 174 nm 5. Which of the following one‐electron species will be the easiest (requires least amount of energy) to ionize? a. N6+ b. F8+ c. K18+ d. He+ e. B4+ 6. An electron in the n= 5 level emits a photon with a wavelength of 1282 nm. To what level has the electron moved? a. n = 1 b. n = 2 c. n = 3 d. n = 4 e. n = ∞ 7. Choose the FALSE statement from below. a. It is possible to know the exact location and speed of an electron at any given time. b. Light has been shown to have momentum. c. All matter travels in waves. d. The energy of an atom is quantized because of the wave motion of electrons. e. Orbitals can be described as the small volume around a nucleus where a particular electron has the highest probability of being found. 8. Which of the following frequencies corresponds to light with the longest wavelength? a. 3.88 x 105 Hz b. 4.97 x 1012 Hz c. 6.73 x 107 Hz d. 2.11 x 109 Hz e. 8.45 x 1015 Hz 9. Which of the following transitions in an H atom would have the highest frequency? a. n = 1 to n = 2 b. n = 2 to n = 4 c. n = 3 to n = 4 d. n = 4 to n = 5 e. n = 3 to n = 6 10. Red light (671 nm) is emitted by excited Li atoms. How much energy is emitted by 0.25 moles of Li atoms? a. 44.6 kJ b. 1.33 x 10‐31 kJ c. 2.96 x 10‐19 kJ d. 20.1 kJ e. 7.40 x 10‐20 kJ