# Exam3 answer - Pietzsch Ashley Exam 3 Due Nov 9 2006 noon...

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Pietzsch, Ashley – Exam 3 – Due: Nov 9 2006, noon – Inst: Brodbelt 1 This print-out should have 23 questions. Multiple-choice questions may continue on the next column or page – ﬁnd all choices before answering. The due time is Central time. Exam 3. You must ﬁll in your version code, name, and EID on your bubblesheet. Save the hardcopy of your exam and self-grade it to make sure your score agrees with the com- puter score. Your score will be posted on the HW Service Web site within 48 hours. Pro- grammable calculators and cell phones may not be used. You may not leave the room dur- ing the exam. If you must leave the room, the exam is over for you. GOOD LUCK!!!! 001 (part 1 of 1) 10 points Which of the following statements is true about a molecule with a bond order of one? 1. The molecule has no electrons in anti- bonding orbitals. 2. The molecule is as stable as molecules with bond orders of two and three. 3. Two side-by-side p orbitals combine to form pi bond and pi antibond orbitals; there- fore the bond order is 1. 4. The molecule has a single bond. correct Explanation: The bond order corresponds to the number of bonds between two atoms. 002 (part 1 of 1) 10 points A 0 . 113 g sample of a gas exerts a pressure of 780 torr in a 50 . 4 mL container at 23 C. What is the molar mass of this gas? 1. 65.3 g/mol 2. 53.1 g/mol correct 3. 96.4 g/mol 4. 34.6 g/mol 5. 242. g/mol Explanation: V = 50 . 4 mL = 0 . 0504 L T = 23 C + 273 = 296 . 15 K P = 780 torr · 1 atm 760 torr = 1 . 02632 atm m = 0 . 113 g Applying the ideal gas law equation, P V = n R T n = P V R T = (1 . 02632 atm) (0 . 0504 L) 296 . 15 K · ± mol · K 0 . 08206 L · atm ² = 0 . 00212847 mol MW = 0 . 113 g 0 . 00212847 mol = 53 . 0897 g / mol 003 (part 1 of 1) 10 points In the heteronuclear diatomic molecule OF, the bonding molecular orbitals have 1. This molecule does not form any molecu- lar orbitals. 2. more oxygen-like atomic orbital charac- ter. 3. no electrons in them. 4. more ﬂuorine-like atomic orbital charac- ter. correct Explanation: The bonding molecular orbitals reﬂect the more electronegative element F and the an- tibonding molecular orbitals reﬂect the less electronegative element O. 004 (part 1 of 1) 10 points What is the molar mass of a gas that di f uses 1.414 times faster than nitrogen (N 2 )? 1. 14.0 g/mol correct 2. 4.85 g/mol 3. 56.0 g/mol

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Pietzsch, Ashley – Exam 3 – Due: Nov 9 2006, noon – Inst: Brodbelt 2 4. 39.5 g/mol 5. 19.8 g/mol Explanation: 005 (part 1 of 1) 10 points Which best describes the hydrogen bonding between two water molecules? hydrogen oxygen 1. correct 2. 3. 4. Explanation: 006 (part 1 of 1) 10 points The density of a gas is 1.96 g/L at STP. What would the mass of 2.00 moles of the gas be at STP? 1.
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## This note was uploaded on 02/04/2010 for the course CH 301 taught by Professor Fakhreddine/lyon during the Fall '07 term at University of Texas.

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Exam3 answer - Pietzsch Ashley Exam 3 Due Nov 9 2006 noon...

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