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Unformatted text preview: padilla (tp5647) HW11: Gases II/Intermolecular forces I shear (52375) 1 This printout should have 28 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points Three of the primary components of air are carbon dioxide, nitrogen, and oxygen. In a sample containing a mixture of only these gases at exactly one atmosphere pressure, the partial pressures of carbon dioxide and ni trogen are given as P CO 2 = 0 . 285 torr and P N 2 = 576 . 822 torr. What is the partial pres sure of oxygen? Correct answer: 182 . 893 torr. Explanation: P CO 2 = 0 . 285 torr P T = 1 atm = 760 torr P N 2 = 576 . 822 torr P O 2 = ? P T = P CO 2 + P N 2 + P O 2 P O 2 = P T ( P CO 2 + P N 2 ) P O 2 = 760 torr (0 . 285 torr + 576 . 822 torr) P O 2 = 182 . 893 torr 002 10.0 points Two gases are contained in gas bulbs con nected by a valve. Gas A is present in a 1 liter bulb at a pressure of 973 torr. Gas B ex erts a pressure of 270 torr in a 1 liter bulb. The valve is opened and the two gases equili brate. What is the partial pressure of gas A expressed after equilibration? Correct answer: 486 . 5 torr. Explanation: V A = 1 L V B = 1 L P A = 973 torr P B = 270 torr V total = 2 L P A V A = P t V t P t = P A V A V t = (973 torr) (1 L) 2 L = 486 . 5 torr 003 10.0 points A sample of oxygen is collected in a 317 mL container over water at 15 C, and the barom eter reads 747 torr. What volume would the dry gas occupy at 710 torr and 15 C? Waters partial pressure at 15 C is 12 . 8 torr. Correct answer: 327 . 805 mL. Explanation: V 1 = 317 mL P 2 = 710 torr T 1 = 15 C= 288 K P 1 H 2 O = 12 . 8 torr T 2 = 15 C = 288 K P T = 747 torr V 2 = ? P T = P O 2 + P H 2 O P O 2 = P T P H 2 O = 747 torr 12 . 8 torr = 734 . 2 torr = P 1 P 1 V 1 T 1 = P 2 V 2 T 2 V 2 = P 1 V 1 T 2 P 2 T 1 = (734 . 2 torr)(317 mL)(288 K) (710 torr)(288 K) = 327 . 805 mL 004 10.0 points Consider two cylinders of gas, both with a volume of 25 L and at 1 atm and 25 C and the following statements. A. The temperature of the gases is different. B. The average kinetic energy of the gases is the same. C. The average molecular speed of the gases is the same. Which statements are true? 1. A and C only 2. A only 3. C only 4. B only correct 5. A and B only 6. B and C only 7. None is true. padilla (tp5647) HW11: Gases II/Intermolecular forces I shear (52375) 2 8. All are true. Explanation: From kinetic molecular theory, the mean kinetic energy of the molecules in a sample of gas is directly proportional to the temper ature of that gas. This means that any two samples of gas at the same temperature have the same mean kinetic energy....
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 Spring '09
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