exam 1B 2-5-07 Answer Key

exam 1B 2-5-07 Answer Key - Mid-term Exam 1 - Chem 1B -...

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Mid-term Exam 1 - Chem 1B - Version B – 2-5-07 1. When a plastic bottle of liquid nitrogen at 77 K comes into contact with air at 298 K the nitrogen boils and forms nitrogen vapor at 77 K. The work for this process is a) Equal to q b) 0 c) Equal to minus q d) Positive e) Negative 2. Combustion of methane in air at constant temperature and pressure leads to the formation of carbon dioxide and water vapor according to the following equation: CH 4 (g) + 2 O 2 (g) CO 2 (g) + 2 H 2 O (g) How is the value of Δ E for this reaction related to its Δ H value? a) Δ E is not related to H b) Δ E is less negative than H c) Δ E is more negative than H d) Δ E is equal to H e) None of the above 3. The enthalpy of formation of one mole of NH 3 (g) is –46 kJ/mol. What is the value of the heat, q, when 1.00 mol of H 2 (g) reacts with excess N 2 (g) to form NH 3 (g) at 298 K and a constant pressure of 1.00 atm? a) –46 kJ b) +46 kJ c) –23 kJ d) +23 kJ e) none of the above 4. Which of the following substances has a Δ H f 0 value equal to zero? a) N 2 ( l ) b) O 2 (g) c) H 2 ( s ) d) C (diamond) e) None of the above Answer e Answer d Answer e A nswer b
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5. When natural gas is ignited in oxygen it spontaneously reacts to produce heat, carbon dioxide and water. Which of the following statements correctly describes this process? a) The reaction is endothermic b) G for this process is positive c) The process is reversible d) Energy can be used to convert the carbon dioxide and water that are produced back into natural gas and oxygen e) None of the above is correct 6. Which of the following statements can be made about the absolute entropy of one mole of O 2 (g) at 298 K and 1.00 atm pressure? a) S 0 = 0 b) S 0 is positive c) S 0 is negative d) S 0 is given by H 0 /T e) None of the above 7. A gas in an insulated container is compressed from a volume of 5.00 L to a volume of 1.00 L. Which of the following statements is true?
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This note was uploaded on 08/06/2008 for the course CHEM 1B taught by Professor Watts during the Winter '08 term at UCSB.

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exam 1B 2-5-07 Answer Key - Mid-term Exam 1 - Chem 1B -...

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