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# #C9F00~1 - CHEM 161-2007 CHAPTER 7 LIGHT AND ATOMIC...

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CHEM 161-2007 CHAPTER 7 – LIGHT AND ATOMIC STRUCTURE PRACTICE PROBLEMS DR. ED TAVSS Light and matter Bohr hydrogen atom De Broglie/Photoelectric effect Quantum nos./orbitals 1

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LIGHT AND MATTER CHEM 161-2006 EXAM III CHAPTER 7 – ATOMIC STRUCTURE LIGHT AND MATTER 20. What is the mass-to-charge ratio for 27 Al 3+ ? The charge on an electron is −1.602 x 10 −19 C. A. 2.8 x 10 −7 kg/C B. 3.1 x 10 −8 kg/C C. 8.8 x 10 −11 kg/C D. 4.7 x 10 −9 kg/C E . 9.3 x 10 −8 kg/C One would assume that the mass to charge ratio is grams of a mole of Al per number of electron change, is 27:3 = 9gAl/electron. However, the convention for mass-to-charge ratio is mass of an atom (in kg)/charge (in Coulombs). -1.602 x 10 -19 C = the electric charge on one electron. (27 g/mol x (1 kg/1000 g)x(1 mol/6.022 x 10 23 atom))/((1.602x10 -19 C/electron) x (3 electrons)) = 9.33 x 10 -8 kg Al/C CHEM 161-2006 EXAM III CHAPTER 7 – ATOMIC STRUCTURE LIGHT AND MATTER 11. A laser produces a light of wavelength 575 nm. How many photons of this light would have to strike a material for the material to absorb 55.1 kJ? A . 1.59 x 10 23 B. 5.31 x 10 22 C. 3.45 x 10 20 D. 6.36 x 10 23 E. 2.76 x 10 22 E photon = hc/λ 2
h = 6.626 x 10 -34 Js c = 3 x 10 8 m/s E photon = ((6.626 x 10 -34 Js) x (3 x 10 8 m/s))/(575 nm x (1 x 10 -9 m/nm)) = 3.457 x 10 -19 J/photon 55100J/(3.457 x 10 -19 J/photon) = 1.59 x 10 23 photons ZUMDAHL 5 TH EDITION CHEM 161-2002 RECITATION 8 TH WEEK CHAPTER 7 - LIGHT, ATOMIC STRUCTURE AND PERIODIC TABLE TRENDS LIGHT AND MATTER 7-37 The laser in an audio compact disc player uses light with a wavelength of 7.80 x 10 2 nm. Calculate the frequency of this light. c = λν c = 3 x 10 8 m/s ν = c /λ (3 x 10 8 m/s)/(780 nm x (1 x 10 -9 m/nm)) = 3.85 x 10 14 s -1 3

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ZUMDAHL 5 TH EDITION CHEM 161-2002 RECITATION 8 TH WEEK CHAPTER 7 - LIGHT, ATOMIC STRUCTURE AND PERIODIC TABLE TRENDS LIGHT AND MATTER 43 It takes 7.21 x 10 -19 J of energy to remove an electron from an iron atom. What is the maximum wavelength of light than can do this? E photon = hν c = λν c = 3 x 10 8 m/s h = 6.626 x 10 -34 Js λ=hc/E ((6.626 x 10 -34 Js) x (3 x 10 8 m/s))/( 7.21 x 10 -19 J) = 2.75 x 10 -7 m 4
CHEM 161- 2002 FINAL EXAM + ANSWERS CHAPTER 7 - LIGHT, ATOMIC STRUCTURE & PERIODIC TABLE TRENDS LIGHT AND MATTER 7. What is the energy of a photon with a wavelength of 459 nm? A. 3.52 xl0 -19 J B. 2.13 xl0 -19 J C. 6.26 xl0 -19 J D . 4.33 xl0 -19 J E. 5.49 xl0 -19 J E = hυ c = λυ E = hc/λ E = ((6.626 x 10 -34 Js) x (3 x 10 8 m/s))/459 x 10 -9 m = 0.0433 x 10 -17 J = 4.33 x 10 -19 J CHEM 161-2000 FINAL EXAM + ANSWERS CHAPTER 7 - LIGHT, ATOMIC STRUCTURE & PERIODIC TABLE TRENDS LIGHT AND MATTER 7. The wavelength of a water wave is 10.0 meter and its speed is 12.0 meter/second. The frequency of the water wave is: A . 1.20 s -1 B. 120 s -1 C. 0.833 s -1 D. 3.00 x 10 8 s -1 E. 12.0 s -1 υ = c/λ υ = (12 m/s)/10.0 m = 1.20s -1 CHEM 161-2000 FINAL EXAM + ANSWERS CHAPTER 7 - LIGHT, ATOMIC STRUCTURE & PERIODIC TABLE TRENDS LIGHT AND MATTER 48. A 5.25 milliwatt (1W = 1J/s) laser produces a beam of radiation with a wavelength of 632.8 nm. How many photons are produced by the laser in 60.0 seconds?

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#C9F00~1 - CHEM 161-2007 CHAPTER 7 LIGHT AND ATOMIC...

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