Exam 1 - Version 175 – Exam 1 – Mccord – (52385) 1...

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Unformatted text preview: Version 175 – Exam 1 – Mccord – (52385) 1 This print-out should have 31 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. McCord CH301 This exam is only for McCord’s CH301 class. c = 3 . 00 × 10 8 m/s h = 6 . 626 × 10- 34 J · s m e = 9 . 11 × 10- 31 kg (electron mass) N A = 6 . 022 × 10 23 mol- 1 1 eV = 1.602 × 10- 19 J ν = R parenleftbigg 1 n 2 y- 1 n 2 x parenrightbigg where R = 3 . 29 × 10 15 s- 1 ψ n ( x ) = parenleftbigg 2 L parenrightbigg 1 2 sin parenleftBig nπx L parenrightBig E n = n 2 h 2 8 mL 2 n = 1 , 2 , 3 , ··· 001 10.0 points For the following graph of Ψ 8 b b b X Y Z one particle in a box solution, at which point would you be most likely to find the particle? 1. point Z 2. point Y correct 3. point X Explanation: 002 10.0 points What is the energy of a photon of 320 nm ultraviolet light? 1. 2 . 10 × 10- 40 J 2. 2 . 10 × 10- 31 J 3. 6 . 21 × 10- 28 J 4. 3 . × 10 +8 J 5. 6 . 21 × 10- 19 J correct Explanation: We need Planck’s constant and the speed of light: c = 2 . 998 × 10 8 m / s λ = 320 nm h = 6 . 626 × 10- 34 J · s Δ E = hν = hc λ = 6 . 626 × 10- 34 J · s · 2 . 998 × 10 8 m / s 320 nm · 10 9 nm 1 m = 6 . 21 × 10- 19 J 003 10.0 points Particles of light are called photons and they have no mass and no charge. 1. False 2. True correct Explanation: A photon is a packet of light. 004 10.0 points Which of the following types of electromag- netic radiation has the shortest wavelength? 1. Microwave 2. Radio 3. Gamma correct 4. Ultraviolet Version 175 – Exam 1 – Mccord – (52385) 2 5. Infrared Explanation: 005 10.0 points The work function for chrominum metal is 4.37 eV. What wavelength of radiation must be used to eject electrons with a velocity of 8200 km / s? 1. 27.3157 2. 15.2719 3. 6.65925 4. 4.65786 5. 10.2696 6. 5.91469 7. 4.47265 8. 91.356 9. 6.34554 10. 28.6611 Correct answer: 6 . 34554 nm. Explanation: v = 8200 km / s = 8 . 2 × 10 6 m / s The wavelength of radiation needed will be the sum of the energy of the work function plus the kinetic energy of the ejected elctron. E work function = (4 . 37 eV) × (1 . 6022 × 10- 19 J / eV) = 7 . 00161 × 10- 19 J E kinetic = 1 2 mv 2 = 1 2 (9 . 10939 × 10- 31 kg) × (8 . 2 × 10 6 m / s) 2 = 3 . 06258 × 10- 17 J E total = E work function + E kinetic = 7 . 00161 × 10- 19 J + 3 . 06258 × 10- 17 J = 3 . 13259 × 10- 17 J Since c = ν λ , E = hν = hc λ λ = hc E = 6 . 626 × 10- 34 m 2 · kg / s 3 . 13259 × 10- 17 J × 3 . × 10 8 m / s = 6 . 34554 × 10- 9 m × 10 9 nm 1 m = 6 . 34554 nm 006 10.0 points Which one of the following isoelectronic ions would be expected to have the largest radius?...
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This note was uploaded on 10/25/2010 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas at Austin.

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Exam 1 - Version 175 – Exam 1 – Mccord – (52385) 1...

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