Chapter 11 Gases and Their Properties 1 Convert 0 449 bar to mm Hg 1 atm 760 mm Hg 101 3 kPa 1 013 bar a 337 mm Hg b 0 591 mm Hg c 5 89 10 4 mm Hg d 0 443 mm Hg e 0 455 mm Hg ANS A 2 At 0 982 atm the height of mercury in a barometer is 0 746 m If the mercury were replaced with ethanol what height of ethanol in meters would be supported at this pressure The densities of Hg and ethanol are 13 5 g cm3 and 0 789 g cm3 respectively a 0 0436 m b 0 946 m c 0 760 m d 12 8 m e 13 0 m ANS D 3 At constant temperature 7 72 L of Cl2 at 458 mm Hg is compressed to 3 75 L What is the final 4 The lid is tightly sealed on a rigid flask containing 2 25 L Ar at 22 C and 0 977 atm If the flask is pressure of Cl2 a 0 485 mm Hg b 0 00106 mm Hg c 222 mm Hg d 943 mm Hg e 1820 mm Hg ANS D heated to 102 C what is the pressure in the flask a 2 86 atm b 1 27 atm c 4 53 atm d 0 769 atm e 1 73 atm ANS B pressure is reduced 442 mm Hg What is the temperature of the gas a 47 0 C b 47 0 C c 89 5 C d 184 C e 188 C ANS B 1 5 A tightly sealed 4 0 L flask contains 884 mm Hg of N2 at 94 0 C The flask is cooled until the 6 You have a 30 0 L cylinder of helium at a pressure of 132 atm and a temperature of 19 C The He is used to fill balloons to a volume of 1 80 L at 745 mm Hg and 27 C How many balloons can be filled with He Assume that the cylinder can provide He until its internal pressure reaches 1 00 atm i e there are 131 atmospheres of usable He in the cylinder a 1 90 102 b 1 06 102 c 4 13 103 d 7 41 103 e 2 29 103 7 At 338 mm Hg and 72 C a sample of carbon monoxide gas occupies a volume of 0 225 L The gas is transferred to a 1 50 L flask and the temperature is reduced to 15 C What is the pressure of the gas in the flask a 8 91 mm Hg b 37 9 mm Hg c 67 8 mm Hg d 3 018 103 mm Hg e 5 48 104 mm Hg ANS E ANS B 8 What volume of oxygen will react with 21 mL of ethanol assuming the gases are present at the same temperature and pressure 2 CH3CH2OH g 6 O2 g 4 CO2 g 6 H2O g a 7 0 mL b 14 mL c 21 mL d 42 mL e 63 mL ANS E the flask R 0 08206 L atm mol K a 0 952 atm b 0 261 atm c 0 311 atm d 0 419 atm e 4 99 atm ANS C 0 08206 L atm mol K a 0 244 g b 5 80 g c 7 82 g d 15 2 g e 56 3 g ANS C 2 9 If 0 357 g of CH4 gas is introduced into an evacuated 1 75 L flask at 25 C what is the pressure inside 10 The pressure of O2 in a 15 0 L flask is 322 mm Hg at 44 C What mass of O2 is in the flask R 11 Calculate the density in g L of CH4 g at 75 C and 2 1 atm R 0 08206 L atm mol K 12 At what temperature does 742 mm Hg of CH4 gas have the same density as 742 mm Hg of O2 gas at a 0 18 g L b 0 85 g L c 1 2 g L d 3 2 g L e 5 5 g L ANS C 273 K a 137 K b 146 K c 191 K d 275 K e 545 K ANS A 13 A mass of 1 37 g of an unknown gas is introduced into an evacuated 1 70 L flask If the pressure in the flask is 0 814 atm at 98 C which of the following gases might be in the flask R 0 08206 L atm mol K a CH4 b C2H2 c C2H6 d C3H8 e C4H10 ANS C 14 What volume of O2 measured at 225 C and 0 970 atm will be produced by the decomposition of 3 16 g KClO3 R 0 08206 L atm mol K 2 KClO3 s 2 KCl s 3 O2 g a 1 09 L b 1 24 L c 1 63 L d 3 26 L e 52 1 L ANS C 15 When 0 5000 grams of an unknown hydrocarbon CxHy is completely combusted with excess oxygen 1 037 L CO2 gas and is produced at 98 3 C and 1 000 atm What is the empirical formula of the hydrocarbon R 0 08206 L atm mol K a CH b CH2 c C2H3 d C3H5 e C3H8 ANS E 16 A mixture of H2 and O2 is placed in a 5 00 L flask at 22 C The partial pressure of the H2 is 2 7 atm and the partial pressure of the O2 is 1 5 atm What is the mole fraction of H2 a 0 13 3 b 0 36 c 0 56 d 0 64 e 0 87 ANS D a 13 6 m s b 42 8 m s c 177 m s d 186 m s e 431 m s ANS E a Ar CH4 N2 N2O b N2O Ar N2 CH4 c N2O N2 CH4 Ar d Ar N2 N2O CH4 e CH4 N2 N2O Ar ANS B 17 What is the root mean square velocity of carbon dioxide molecules at 55 C 18 Place the following gases in order of increasing average velocity at 300 K Ar CH4 N2 and N2O 19 Methane gas CH4 effuses through a barrier at a rate of 0 568 mL minute If an unknown gas effuses through the same barrier at a rate of 0 343 mL minute what is the molar mass of the gas a 20 8 g mol b 28 0 g mol c 32 0 g mol d 44 0 g mol e 64 0 g mol ANS D 4