Exam_3_practice_key_2010

Exam_3_practice_key_2010 - CHEM 222, Fall 2009 (Exam #3)...

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CHEM 222, Fall 2009 (Exam #3) You have 50 min in which to take this exam. It is a closed book exam; only calculators are allowed. Show all of your work. Physical Constants (not all need to be used) c = 2.998 × 10 8 m/s h = 6.626 × 10 -34 J × s J = N m = kg m 2 /s 2 1 eV = 1.602 x 10 -19 J Atomic mass unit, u = 1.660 x 10 -27 kg; Mass of an electron, 9.11 x 10 -28 g
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Problem # 1 (12 pts) (A) Calculate the de Broglie wavelength of an electron with a velocity of 6.00 x 10 6 m/s. (B) Using the de Broglie equation, calculate the mass of a “blue” photon, λ = 400 nm. A. ) s / m 10 00 . 6 ( ) g 10 11 . 9 ( 10 626 . 6 mv h 6 28 34 × × × = = λ - - = 1.21 x 10 -13 J s 2 m -1 g -1 converting g to kg, and from kg m 2 /s 2 to Joules, = 1.21 x 10 -13 J s 2 m -1 g -1 (1000g / 1kg)(1kg m 2 s -2 /1J) = 1.21 x 10 -10 m = 0.121 nm B. mv h p h = = λ , ) s / m 10 998 . 2 ( ) m 10 400 ( Js 10 626 . 6 v h m 8 9 34 × × × = λ = - - = 5.53 x 10 -36 kg
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Problem #2 (18 pts) Complete the following table (show the equations you use). Type of Spectroscopy Wavelength Frequency, Hz Wavenumber, cm -1 Energy, J Vacuum UV 175 nm 1.71 x 10 15 5.71 x 10 4 1.13 5 x 10 -18 UV-Vis 780 nm 3.84 x 10 14 1.28 x 10 4 2.55 x 10 -19 Infrared 300 μ m 9.99 x 10 11 33.3 6.62 x 10 -22 For Vacuum UV, 175 nm m 10 175 s / m 10 998 . 2 c Frequency 9 8 - × × = λ = = 1.71 x 10 15 /s Wavenumber = 1/λ = 1/ (175 x 10 -9 m x 100 cm/1m) = 5.71 x 10 4 cm -1 Energy = hν = m 10 175 ) s / m 10 998 . 2 )( Js 10 626 . 6 ( hc 9 8 34 - - × × × = λ = 1.13 5 x 10 -18 J Or you can calculate energy using frequency. E = hν = (6.626 x 10 -34 Js)(1.71 x 10 15 Hz) = 1.13 x 10 -18 J It is the same calculation (with different numbers) for the remaining two.
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Problem # 3 (15 pts) A Raman spectrum of a compound was taken with 488.0 nm excitation radiation, and a
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Exam_3_practice_key_2010 - CHEM 222, Fall 2009 (Exam #3)...

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