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Unformatted text preview: roberts (eer474) Sample Exam One Shear (52375) 1 This printout should have 30 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. In all cases, select the answer that BEST answers the question asked. The total points on this exam is 300. Some questions provide fundamental constants in addition to those given here and on the scantron sheet. Watch your units! Shear 52375 c = 3 . 00 10 8 m/s h = 6 . 626 10 34 J s m e = 9 . 11 10 31 kg N A = 6 . 022 10 23 mol 1 E = R parenleftbigg 1 n 2 1 1 n 2 2 parenrightbigg where R = 2 . 178 10 18 J n ( x ) = parenleftbigg 2 L parenrightbigg 1 2 sin parenleftBig nx L parenrightBig E n = n 2 h 2 8 mL 2 n = 1 , 2 , 3 , 001 10.0 points Iron reacts with Cl 2 according to the equation 2 Fe(s) + 3 Cl 2 (g) 2 FeCl 3 (s) . How many moles of Cl 2 is needed to react with 4.4 mol Fe? 1. 6.6 correct 2. 3.3 3. 3.0 4. 4.4 Explanation: n Fe = 4.4 mol The balanced equation for the reaction in dicates that 3 mol Cl 2 are needed for every 2 mol Fe reacted. Using this mole ratio we find the moles Cl 2 needed to completely react 4.4 mol Fe: ? mol Cl 2 = 4 . 4 mol Fe 3 mol Cl 2 2 mol Fe = 6 . 6 mol Cl 2 002 10.0 points Which of the following is not a permitted combination of quantum numbers? 1. n = 4, = 3, m = 3, m s = 1 2 2. n = 3, = 0, m = 0, m s = 1 2 3. n = 4, = 2, m = 1, m s = 1 2 4. n = 2, = 1, m = 2, m s = 1 2 correct 5. n = 3, = 0, m = 0, m s = 1 2 Explanation: For n = 2, m can only have values of 1, 0, and +1. 003 10.0 points If a particle is confined to a onedimensional box of length 300 pm, for 3 the particle has zero probability of being found at 1. 150 pm only. 2. 50, 150, and 250 pm, respectively. 3. 50 and 250 pm, respectively. 4. 75, 125, 175, and 225 pm, respectively. 5. 100 and 200 pm, respectively. correct Explanation: 100 200 300 roberts (eer474) Sample Exam One Shear (52375) 2 004 10.0 points In a hydrogen atom which transition would emit the longest wavelength light? 1. n = 5 to n = 4 correct 2. n = 5 to n = 3 3. n = 1 to n = 2 4. n = 4 to n = 3 5. n = 2 to n = 4 6. n = 2 to n = 1 Explanation: To emit the first level needs to be higher energy than the second level. The longest wavelength will be lowest frequency. This will come from the two levels that are closest together. This is the n = 5 to n = 4 transition. 005 10.0 points Rank the following atoms in terms of decreas ing atomic radius. 1. F, O, N, Na, Mg 2. Na, N, O, Mg, F 3. F, O, N, Mg, Na 4. Na, Mg, N, O, F correct 5. F, Mg, Na, O, N Explanation: As you move down the periodic table atomic radius increases because the shielding effects of inner electrons reduces the effective nuclear charge experienced by outer shell elec trons. As you move across the periodic table the radius decreases because electrons are be ing added to the same electronic shell (and thus do not add additional shielding effects)...
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This note was uploaded on 11/08/2010 for the course CHEM 301 taught by Professor Wandelt during the Spring '08 term at University of Texas at Austin.
 Spring '08
 wandelt
 Chemistry

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