che3 - Version 074 Exam 3: Shear shear (52375) 1 This...

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Unformatted text preview: Version 074 Exam 3: Shear shear (52375) 1 This print-out should have 28 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. DrRuth says: In all cases, select the answer that BEST answers the question asked. The total points on this exam is 350, but it counts equally with the previous exams that were 400 points. Read the whole thing first and plan which to answer first because you feel confident about them. Notice the harder ones and save them up till last so you dont use up all your time working on them. Shear 52375 g = 9 . 8 m / s 2 1 atm = 101325 Pa = 760 torr R = see back of answer sheet ( P + a ( n/V ) 2 )( V- nb ) = nRT 001 15.0 points Which one of the following statements is FALSE? 1. When one considers the molecular or- bitals resulting from the overlap of any two specific atomic orbitals, the bonding orbitals are always lower in energy than the antibond- ing orbitals. 2. One of the shortcomings of valence bond theory is its inability to account for the para- magnetism of O 2 . 3. Valence bond theory and molecular or- bital theory can be described as two different views of the same thing. 4. One of the shortcomings of molecular or- bital theory is its inability to account for a triple bond in the N 2 molecule. correct 5. Molecular orbitals are generally described as being more delocalized than hybridized atomic orbitals. Explanation: The molecular orbital theory predicts a bonding order of 3 for N 2 , which is equiva- lent to a triple bond. 002 10.0 points Under what conditions is a gas most likely to deviate from ideal behavior? 1. when considering noble gases 2. high pressure correct 3. high temperatures 4. low density Explanation: Under high pressure, there are many more collisions between molecules. This increases the likelihood that a non-ideal interaction will occur. 003 10.0 points Which would you expect to be least viscous? 1. C 8 H 18 at 50 C 2. C 8 H 18 at 30 C 3. C 4 H 8 at 50 C correct 4. C 4 H 8 at 30 C Explanation: 004 20.0 points An ideal gas occupies 45.0 L at 938 torr and 36.8 C. What volume would it occupy at STP? 1. 0.0204 L 2. 81.8 L 3. 63.0 L 4. 0.0159 L 5. 48.9 L correct Version 074 Exam 3: Shear shear (52375) 2 6. 50.9 L 7. 60.6 L 8. 37.7 L 9. 22.4 L Explanation: P 1 = 938 torr P 2 = 760 torr V 1 = 45 L T 2 = 309 . 95 K T 1 = 36 . 8 C + 273 . 15 = 309 . 95 K Using the Combined Gas Law P 1 V 1 T 1 = P 2 V 2 T 2 , and recalling that STP implies standard tem- perature (0 C or 273.15 K) and pressure (1 atm or 760 torr), we have V 2 = P 1 V 1 T 2 T 1 P 2 = (938 torr) (45 L) (273 . 15 K) (309 . 95 K) (760 torr) = 48 . 9453 L 005 10.0 points If it takes 15 s for a certain sample of neon to effuse through a porous barrier, how much time will it take for the same amount of ni- trogen gas to effuse through the barrier under the same conditions?...
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This note was uploaded on 03/31/2010 for the course CH ch302 taught by Professor F during the Spring '09 term at University of Texas-Tyler.

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che3 - Version 074 Exam 3: Shear shear (52375) 1 This...

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