UMass_F03_FinalExamKey

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Unformatted text preview: Page 1 of 12 Name: _______________________________ Chem 111 10:10a section Final Exam This exam is composed of 50 questions. Go initially through the exam and answer the questions you can answer quickly . Then go back and try the ones that are more challenging to you and/or that require calculations. Periodic table, solubility rules, and valuable constants are on the last page of the exam. Feel free to tear it off. As discussed on the course syllabus, honesty and integrity are absolute essentials for this class. In fairness to others, dishonest behavior will be dealt with to the full extent of University regulations. 1. The average molecular speed in a sample of N 2 gas is 478 m/s at 303 K. The average molecular speed in a sample of CO 2 gas at the same temperature is: 1) 304 m s-1 2) 381 m s-1 3) 478 m s-1 4) 326 m s-1 5) 600 m s-1 (2) Same temperature means same kinetic energy, so (OWL 12-6d) KE = 1 2 m N 2 u N 2 2 = 1 2 m CO 2 u CO 2 2 u CO 2 2 = m N 2 m CO 2 u N 2 2 = 2 x 14.01 g mol − 1 ( ) 12.01 g mol − 1 ( ) + 2 x 16.00 g mol − 1 ( ) 478 m s − 1 ( ) 2 = 145500 m s − 1 ( ) 2 = 381 m s − 1 ( ) 2 2. A 1.28 mol sample of Ar gas is confined in a 31.5 liter container at 26.5 °C. If 1.28 mol of F 2 gas is added while doubling the volume and keeping the temperature constant, the average kinetic energy per molecule will: 1) decrease 2) remain the same 3) increase 4) not enough information 5) I don’t have a clue (2) Temperature determines average kinetic energy Chapter 12 3. A sample of Cl 2 gas is confined in a 2.0 liter container at 50 °C. Then 2.5 mol of He is added, holding both the volume and temperature constant. The pressure will increase because: 1) As the number of molecule-wall collisions increases, the force per collision increases. 2) With more molecules per unit volume, the molecules hit the walls of the container more often. 3) With more molecules in the container, the molecules have higher average speeds. 4) With higher average speeds, on average the molecules hit the walls of the container with more force. 5) None of the Above (2) Chapter 12 Page 2 of 12 Name: _______________________________ 4. A 1.96 mol sample of CO 2 gas is confined in a 49.1 liter container at 32.3 °C. If the temperature of the gas sample is increased to 55.0 °C, holding the volume constant, the pressure will increase because: 1) With higher average speeds, on average the molecules hit the walls of the container with more force. 2) With lower average speeds, the molecules hit the walls of the container less often. 3) As the average speed increases, the number of molecule-wall collisions decreases. 4) None of the above (1) Chapter 12 5. In our bodies, sugar is broken down with oxygen to produce water and carbon dioxide....
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This note was uploaded on 02/06/2011 for the course CHEM 111 taught by Professor Craigmartin during the Fall '08 term at UMass (Amherst).

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UMass_F03_FinalExamKey - Page 1 of 12 Name:...

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