Name: Class: Date: ID: A Chemistry Honors - Gases Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Why does a can collapse when a vacuum pump removes air from the can? a. The inside and outside forces balance out and crush the can. b. The unbalanced outside force from atmospheric pressure crushes the can. c. The atmosphere exerts pressure on the inside of the can and crushes it. d. The vacuum pump creates a force that crushes the can. 2. Which instrument measures atmospheric pressure? a. barometer c. vacuum pump b. manometer d. torrometer 3. A pressure of 745 mm Hg equals a. 745 torr. c. 1 pascal. b. 1 torr. d. 745 pascal. 4. Convert the pressure 0.840 atm to mm Hg. a. 365 mm Hg c. 638 mm Hg b. 437 mm Hg d. 780 mm Hg 5. Convert the pressure 1.95 atm to kpa. a. 1 kpa c. 760 kpa b. 198 kpa d. 1013 kpa 6. A mixture of four gases exerts a total pressure of 878 mm Hg. Gases A and B each exert 193 mm Hg. Gas C exerts 130 mm Hg. What pressure is exerted by gas D? a. 165 mm Hg c. 878 mm Hg b. 362 mm Hg d. 193 mm Hg Use the table below to answer the following questions. Water Vapor Pressure Temperature (ºC) Pressure (mm Hg) 0 4.6 5 6.5 10 9.2 15 12.8 20 17.5 25 23.8 30 31.8 35 42.2 40 55.3 50 92.5 7. What is the partial pressure of water vapor in oxygen gas collected by water displacement at 10ºC and 788 mm Hg? a. 9.2 mm Hg c. 6.5 mm Hg b. 778.8 mm Hg d. 797.2 mm Hg 1
Name: ID: A 8. A sample of gas is collected by water displacement at 644.6 mm Hg and 30ºC. What is the partial pressure of the gas? a. 612.8 mm Hg c. 674.6 mm Hg b. 644.6 mm Hg d. 676.4 mm Hg 9. The volume of a gas is 400.0 ml when the pressure is 1.00 atm. At the same temperature, what is the pressure at which the volume of the gas is 2.0 L? a. 0.5 atm c. 0.20 atm b. 5.0 atm d. 800 atm 10. The volume of a gas is 5.9 L when the temperature is 5.0ºC. If the temperature is increased to 10.0ºC without changing the pressure, what is the new volume? a. 3.0 L c. 6.0 L b. 5.8 L d. 11.8 L 11. The volume of a gas is 93 ml when the temperature is 91ºC. If the temperature is reduced to 0ºC without changing the pressure, what is the new volume of the gas? a. 70. ml c. 120 ml b. 93 ml d. 273 ml 12. On a cold winter morning when the temperature is 13ºC, the air pressure in an automobile tire is 1.5 atm. If the volume does not change, what is the pressure after the tire has warmed to 19ºC? a. 1.5 atm c. 3.0 atm b. 1.7 atm d. 1.3 atm 13. If 0.5 L of O 2 (g) reacts with H 2 to produce 1 L of H 2 O(g), what is the volume of H 2 O(g) obtained from 1 L of O 2 (g)? a. 0.5 L c. 2 L b. 1.5 L d. 2.5 L 14. In the reaction represented by the equation N 2 (g) + 2O 2 (g) 2NO 2 (g), what is the volume ratio of N 2 to NO 2? a. 1:1 c. 2:1 b. 1:2 d. 2:5 15. What is the number of moles of H 2 produced when 23 g of sodium react with water according to the equation 2Na(s) + 2H 2 O(l) 2NaOH(aq) + H 2 (g)? a. 0.50 mol c. 2.0 mol b. 1.0 mol d. 4.0 mol 16. Equal volumes of diatomic gases under the same conditions of temperature and pressure contain the same number of a. protons. c. molecules. b. ions. d. electrons. 17. At constant temperature and pressure, gas volume is directly proportional to the a. molar mass of the gas. c. density of the gas at STP. b. number of moles of gas. d. rate of diffusion. 18. The standard molar volume of a gas at STP is a. 22.4 L. c. g-mol wt/22.4 L. b. g/22.4 L. d. 1 L. 19. A 1.00 L sample of a gas has a mass of 1.91 g at STP. What is the molar mass of the gas? a. 1.91 g/mol c. 22.4 g/mol b. 19.1 g/mol d. 42.8 g/mol 2
Name: ID: A 20. Chlorine is produced by the reaction 2HCl(g) H 2 (g) + Cl 2 (g). How many grams of HCl (36.5 g/mol) must be used to produce 10.0 L of chlorine at STP? a. 15.8 g c. 32.6 g b. 30.2 g d. 36.5 g 21. What is the value of the gas constant? a. 0.0821 L atm c. 0.0281 L atm mol K mol K b. 0.281 L atm d. 0.0821 mol K 22. A gas occupies a volume of 2.4 L at 14.1 kpa. What volume will the gas occupy at 84.6 kpa? a. 497 L c. 14 L b. 2.5 L d. 0.40 L 23. A sample of gas occupies 17 ml at 112C. What volume does the sample occupy at 70C? a. 10.6 ml c. 36mL b. 27 ml d. 8.0mL 24. If a balloon containing 3000 L of gas at 39C and 99 kpa rises to an altitude where the pressure is 45.5 kpa and the temperature is 16C, the volume of the balloon under these new conditions would be calculated using the following conversion factor ratios:. a. 3000 L 99 45.5 16 39 b. 3000 L 312 289 45.5 99 c. 3000 L 289 312 99 45.5 d. 3000 L 39 16 45.5 99 25. A breathing mixture used by deep-sea divers contains helium, oxygen, and carbon dioxide. What is the partial pressure of oxygen at 101.4 kpa if P He = 82.5 kpa and P CO 2 = 0.4 kpa? a. 82.9 kpa c. 18.5 kpa b. 19.3 kpa d. 101.0 kpa 26. When a container is filled with 3.00 moles of H 2, 2.00 moles of O 2, and 1.00 mole of N 2, the pressure in the container is 768 kpa. What is the partial pressure of O 2? a. 256 kpa c. 128 kpa b. 128 kpa d. 192 kpa 27. Calculate the approximate volume of a 0.600 mol sample of gas at 15.0 C and a pressure of 1.30 atm. a. 19.5 L c. 10.9 L b. 0.6 L d. 54.2 L 28. A gas sample with a mass of 16.7 g exerts a pressure of 1.36 atm at 15ºC and a volume of 2.91 L. What is the molar mass of the gas? a. 99.8 g/mol c. 18.8 g/mol b. 2.8 g/mol d. 14.8 g/mol Short Answer 29. A gas has a pressure of 747 kpa at 227C. What will its pressure be at 27C, if the volume does not change? 30. A gas occupies a volume of 145 ml at 35C and 95 kpa. What is the volume of the gas at STP? 31. A gas storage tank has a volume of 3.5 10 5 m 3 when the temperature is 27C and the pressure is 97 kpa. What is the new volume of the tank if the temperature drops to 10C and the pressure drops to 98 kpa? 3
Name: ID: A 32. How many moles of N 2 are in a flask with a volume of 175 ml at a pressure of 300.0 kpa and a temperature of 300.0 K? 33. The gaseous product of a reaction is collected in a 25.0-L container at 27C. The pressure in the container is 300.0 kpa and the gas has a mass of 95.3 g. How many moles of the gas are in the container? What is the molar mass of the gas? 34. What is the pressure exerted by 64 g of O 2 in a 88.0-L container at 30.0C? 35. A mixture of gases at a total pressure of 86 kpa contains N 2, CO 2, and O 2. The partial pressure of the CO 2 is 21 kpa and the partial pressure of the N 2 is 46 kpa. What is the partial pressure of the O 2? 36. Use Graham s law to calculate how much faster fluorine gas, F 2, will effuse than chlorine gas, Cl 2, will. The molar mass of F 2 = 38.0; the molar mass of Cl 2 = 70.9. Problem Use the table below to answer the following questions. Element Atomic Mass Argon 39.948 Bromine 79.904 Carbon 12.011 Chlorine 35.453 Fluorine 18.998 Helium 4.0026 Hydrogen 1.0079 Nitrogen 14.007 Oxygen 15.999 37. A gas sprayed from an aerosol can effuse 2.33 times slower than nitrogen diffuses. What is the molar mass of the unknown gas? 38. A steam vent releases an unknown gas along with steam. This gas travels 1.48 times as slowly as the steam. What is the molar mass of the unknown gas? 4
Chemistry Honors - Gases Answer Section MULTIPLE CHOICE 1. ANS: B PTS: 1 DIF: II REF: 1 OBJ: 1 2. ANS: A PTS: 1 DIF: I REF: 1 OBJ: 1 3. ANS: A PTS: 1 DIF: I REF: 1 OBJ: 2 4. ANS: C 0.840 atm 760 mm Hg 1atm 638.4 or 638 mm Hg PTS: 1 DIF: II REF: 1 OBJ: 2 5. ANS: B 101.325 kpa 1.95 atm 198 kpa 1atm PTS: 1 DIF: II REF: 1 OBJ: 2 6. ANS: B PTS: 1 DIF: III REF: 1 OBJ: 3 7. ANS: A PTS: 1 DIF: III REF: 1 OBJ: 3 8. ANS: A PTS: 1 DIF: III REF: 1 OBJ: 3 9. ANS: C P 2 P 1 V 1 1.00 atm 400.0 ml 2000 ml 0.20 atm PTS: 1 DIF: III REF: 2 OBJ: 2 10. ANS: C V 1 5.9 L 283 K 278 K 6.0L PTS: 1 DIF: III REF: 2 OBJ: 3 1
11. ANS: A V 1 93 ml 273 K 364 K 69.8 or 70. ml PTS: 1 DIF: III REF: 2 OBJ: 3 12. ANS: B P 2 P 1 1.5 atm (19 273) K 260 K 1.7 atm PTS: 1 DIF: III REF: 2 OBJ: 4 13. ANS: C Ratio O 2 :H 2 O is 1:2, therefore, 1 L O 2 2LH 2 O PTS: 1 DIF: II REF: 3 OBJ: 1 14. ANS: B PTS: 1 DIF: II REF: 3 OBJ: 1 15. ANS: A 23gNa 1molNa 22.99 g Na 1molH 2 2molNa 0. 50 mol H 2 PTS: 1 DIF: III REF: 3 OBJ: 1 16. ANS: C PTS: 1 DIF: I REF: 3 OBJ: 2 17. ANS: B PTS: 1 DIF: I REF: 3 OBJ: 2 18. ANS: A PTS: 1 DIF: I REF: 3 OBJ: 3 19. ANS: D n PV RT 1atm 1.00 L 0.0821 L atm/(mol K) 273 K 0.04462 mol 1.91 g or 1.91 g 42.8 g/mol 0.04462 mol 0.04462 mol PTS: 1 DIF: III REF: 3 OBJ: 3 20. ANS: C 10.0 L Cl 2 1molCl 2 2molHCl 22.4 L Cl 2 1molCl 2 36.46 g HCl 1molHCl 32.554 or 32.6 g HCl PTS: 1 DIF: III REF: 3 OBJ: 3 2
21. ANS: A PTS: 1 DIF: I REF: 3 OBJ: 4 22. ANS: D PTS: 1 DIF: L2 REF: p. 419 OBJ: 14.2.1 23. ANS: C PTS: 1 DIF: L2 REF: p. 421 OBJ: 14.2.1 24. ANS: C PTS: 1 DIF: L2 REF: p. 419 OBJ: 14.2.2 25. ANS: C PTS: 1 DIF: L2 REF: p. 434 OBJ: 14.4.1 26. ANS: A PTS: 1 DIF: L2 REF: p. 434 OBJ: 14.4.1 27. ANS: C T = 273.15 + 15 = 288.15K V ( 0.600 288.15 0.0821) 1.30 V 10.9 PTS: 1 28. ANS: A PTS: 1 SHORT ANSWER 29. ANS: 227C + 273 = 500 K 27C + 273 = 300 K P 1 = P 2 747 kpa ; 500 K = P 2 300 K 747 kpa 300 K 500 K = P 2 P 2 = 448 kpa PTS: 1 DIF: L3 REF: p. 421 OBJ: 14.2.1 30. ANS: = 35C + 273 = 308 K = 0.0C + 273 = 273 K = P 1 V 1 P 2 = 95 kpa 145 ml 273 K 308 K 101 kpa = 121 ml PTS: 1 DIF: L3 REF: p. 424 OBJ: 14.2.2 3
31. ANS: = 27C + 273 = 300 K; P 1 = 97 kpa = 10C + 273 = 263 K; P 2 = 98 kpa = P 1 V 1 = (97 kpa) (3.5 10 5 m 3 ) P 2 = 3.0 10 5 m 3 263 K 300 K 98 kpa PTS: 1 DIF: L3 REF: p. 424 OBJ: 14.2.2 32. ANS: 1L 175 ml 1000 ml = 0.175 L n = P PV RT = 300.0 kpa 0.175 L = 0.021 mol 8.31 (L kpa)/(k mol) 300.0 K PTS: 1 DIF: L2 REF: p. 427 OBJ: 14.3.1 33. ANS: n = PV RT = 300.0 kpa 25.0 L 8.31 (L kpa)/(k mol) 300 K 3.01mol 95.3g 3.01mol 31.7g / mol PTS: 1 DIF: L2 REF: p. 427 OBJ: 14.3.1 34. ANS: 64 g O 2 1molO 2 32 g O 2 = 2 mol O 2 P = nrt V 2mol 8.31 (L kpa)/(k mol) 303 K = 88.0 L = 57 kpa PTS: 1 DIF: L2 REF: p. 427 OBJ: 14.3.1 35. ANS: P O 2 = P total (P CO 2 + P N 2 ) = 86 kpa (21 kpa + 46 kpa) = 19 kpa PTS: 1 DIF: L2 REF: p. 434 OBJ: 14.4.1 36. ANS: Rate F 2 /Rate Cl 2 (70.9 / 38.0) = 1.4 PTS: 1 DIF: L2 REF: p. 436 OBJ: 14.4.2 4
PROBLEM 37. ANS: 152 g/mol m 28.02 g/mol (2.33) 2 152 g/mol PTS: 1 DIF: III REF: 4 OBJ: 3 38. ANS: 39.5 g/mol m 18.02 g/mol (1.48) 2 39.5 g/mol PTS: 1 DIF: III REF: 4 OBJ: 3 5