Past Midterm

Past Midterm - Previous Midterm Questions These questions...

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Previous Midterm Questions These questions were taken from previous midterm examinations from CHEM 120, which may be of assistance to you in studying. Please remember however that the course, and instructors, change from year to year, so many of these questions will not be as relevant to this year’s CHEM 120 as some. This gives the impression of being more difficult than they were when given, since different homework was assigned, and more time may have been spent in class in some of these topics. Some terminology and variables may have changed somewhat too. Good luck studying. Solutions are also posted to WEB CT. 1. What is the work in joules done on the system to compress He gas from 24.0 L to 12.5 L against a pressure of 1.5 atm at a constant temperature of 37.4 ºC ? a. 5.5 × 10 3 b. –17 c. 17 d. 1.7 × 10 3 e. –1.7 × 10 3 2. 246 g of hot coffee at 86.0 ºC are placed in a 137 g mug at 20.0 ºC. The specific heat of coffee is 4.00 J/g ºC, while that of the mug is 0.752 J/g ºC. Assuming that no heat is lost to the surroundings, what is the final temperature of the system: mug + coffee? a. 79.7 ºC b. 93.7 ºC c. 98.4 ºC d. 76.0 ºC e. 53.0 ºC 3. If the volume of a gas is doubled but the temperature remains constant, then: a. the pressure stays the same. b. the molecules move faster. c. the kinetic energy increases. d. the molecules move more slowly. e. none of these answers is correct. 4 . If we consider the Universe as one large thermodynamic system, we can say that over time : a. both the total Energy and the total Entropy are increasing. b. the total Energy is increasing and the total Entropy is decreasing. c. the total Energy is constant and the total Entropy is increasing. d. both the total Energy and the total Entropy are constant. e. the total Energy is decreasing and the total Entropy is increasing.
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5. To increase the volume of a fixed amount of gas from 100 cm 3 to 200 cm 3 , you could: a. increase the temperature from 25.0 ºC to 50.0 ºC at constant pressure. b. increase the pressure from 1.00 atm to 2.00 atm at constant temperature. c. reduce the temperature from 400 K to 200 K at constant pressure. d. reduce the pressure from 608 Torr to 0.40 atm at constant temperature. e. decrease the temperature from 600 K to 400 K. 6. 2 NOCl(g) ± 2 NO(g) + Cl 2 (g) H º = +75.56 kJ/mol 2 NO(g) + O 2 (g) ± 2NO 2 (g) H º = -113.05 2NO 2 (g) ± N 2 O 4 (g) H º = -58.03 Calculate the H º of: N 2 O 4 (g) + Cl 2 (g) ± 2 NOCl(g) + O 2 (g) in kJ/mol. a. +246.65 b. –95.52 c. –246.65 d. +95.52 e. none of these 7. What volume would be occupied by 4.8 g of oxygen gas at 0.50 atm and 133 ºC? a. 20 L b. 13 L c. 10 L d. 6.7 L e. 3.3 L 8. If 356 J of work is done by a system while it loses 289 J of heat to the surroundings, what is the value of U ? a. +645 J
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This note was uploaded on 08/23/2008 for the course BIOL 111 taught by Professor Brianmcgill during the Fall '07 term at McGill.

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Past Midterm - Previous Midterm Questions These questions...

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