Answers Version B First Mid 2-1-08

Answers Version B First Mid 2-1-08 - Chemistry 1B First...

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1 Chemistry 1B First Mid-Term Exam, 2-1-08 Answer Key Version B . 1. An ice cube is removed from an ice cube tray in a freezer at -15 o C and placed in an empty glass at 25 o C. The ice cube melts to form water at 25 o C. Then the water is poured back into the ice cube tray and placed back in the freezer where it freezes to form ice at -15 o C. Which of the following statements is true ? A. S for the process is positive. B. E for the process is negative. C. H for the process is positive. D. q irr /T for the process is negative. E. None of the above. 2. One mole of an ideal gas with a volume of 22.4 L and a pressure of 1.0 atm is allowed to expand at constant T = 273 K into an evacuated bulb to a total volume of 224 L. What is the value of q irr /T for this gas expansion? A. 0 B. 19.1 J/K C. Positive number less than 19.1 J/K D. Positive number more than 19.1 J/K E. None of the above 3. The temperature of 3.00 mol of ethane (C 2 H 6 ) is increased from 25.0°C to 50°C in a rigid vessel (constant volume). Cv for C 2 H 6 = 44.6 J/K·mol. What is the value of the internal energy change, Δ E, for this process? A. 3345 J B. 1115 J C. -3345 J D. -1115 J E. 6690 J 4. For nitrogen gas the values of Cv and Cp at 25°C are 20.8 J K-1 mol-1 and 29.1 J K-1 mol-1, respectively. When a sample of nitrogen is heated at constant pressure, what fraction of the energy is converted to heat?
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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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Answers Version B First Mid 2-1-08 - Chemistry 1B First...

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