exam 3 - Version 097 Exam 3 mcdevitt (52365) This print-out...

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Version 097 – Exam 3 – mcdevitt – (52365) 1 This print-out should have 27 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points What is the total pressure exerted by a mix- ture oF 2.00 grams oF hydrogen gas and 8.00 grams oF nitrogen gas at zero degrees Celsius in a 10.0 liter vessel? 1. 2.86 atm correct 2. 0.244 atm 3. 1.00 atm 4. 0.800 atm 5. 0.655 atm Explanation: 002 10.0 points Which is the weakest type oF attractive Force between particles? 1. covalent bond 2. dispersion Forces correct 3. ionic bond 4. hydrogen bond Explanation: London Forces, dispersion Forces, or induced dipoles all describe the same intermolecular Force. London Forces are induced, short-lived, and very weak. Molecules and atoms can experience London Forces because they have electron clouds. London Forces result From the distortion oF the electron cloud oF an atom or molecule by the presence oF nearby atoms or molecules. Permanent dipole-dipole interactions are stronger than London Forces and occur be- tween polar covalent molecules due to charge separation. H-bonds are a special case oF very strong dipole-dipole interactions. They only occur when H is bonded to small, highly electro- magnetic atoms – ±, O or N only. Ion-ion interactions are the strongest due to extreme charge separation and occur between ionic molecules. They can be thought oF as both inter- and intramolecular bonding. 003 10.0 points What are the strongest inter molecular Forces present in a liquid sample oF PCl 3 ? 1. dispersion 2. dipole-dipole correct 3. covalent 4. hydrogen bonding 5. interionic Explanation: 004 10.0 points At a certain low temperature the conductivity oF a metal suddenly increases. This is 1. the boiling point oF liquid helium. 2. absolute zero, since molecular motion ceases at this point. 3. at the crystallization temperature oF the metal. 4. the superconducting transition tempera- ture. correct Explanation: 005 10.0 points Considering the ideal gas law P V = nRT , what is P directly proportional to? 1. only V 2. n and T correct 3. only T
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Version 097 – Exam 3 – mcdevitt – (52365) 2 4. T and V 5. only n Explanation: Rearrange the equation so that P is the subject of the formula: P = nRT V R is the gas constant and does not appear in any of the responses. V is in the denominator; P is inversely proportional to V . T and n are in the numerator; P is directly proportional to both n and T , meaning as the number of moles of a gas or the temperature of a gas increases, the pressure will also increase by the same factor. 006 10.0 points Valence band theory deals with the valence band and conduction band of various chemical species. Which substance would have the largest gap between these two bands? 1.
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exam 3 - Version 097 Exam 3 mcdevitt (52365) This print-out...

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