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Quiz 1 Constants and conversion factors that you would need: R = 8.314 J mol-1 k-1 = 8.314 kPa L mol-1 k-1 = 0.082 atm L mol-1 k-1 NA = 6.023x1023 , k = 1.38x10-23 J K-1 , π = 3.14 1 atm = 760 torr = 101325 Pa , 1 Å = 10-10 m H = 1 , C = 12 , N = 14 , O = 16 , F = 19 , S =32 , Cl = 35.5 , 1) How many molecules of gas are there in a 45.0 L container at 25.0°C and 500.0 mm Hg? A) 0.63 x10-23 B) 6.11 x1022 C) 1.84x1023 D) 7.29x1023 2) The volume of a sample of gas (2.49 g) was 752 mL at 1.98 atm and 62°C. The gas is A) SO2 B) SO3 C) NH3 D) NO2 3) A mixture of Xe, Kr, and Ar has a total pressure of 6.70 atm. What is the mole fraction of Kr if the partial pressures of Xe and Ar are 1.60 atm and 2.80 atm, respectively. A) 0.174 B) 0.256 C) 0.343 D) 0.481 4) According to kinetic-molecular theory, in which of the following gases will the root-meansquare speed of the molecules be the highest at 200°C? A) HCl B) Cl2 C) H2O D) SF6 5) At STP (1 atm, 0 oC), the average speed of CH4 at, in m s-1, is: A) 455 B) 425 C) 601 D) 1701 6) A real gas will behave most like an ideal gas under conditions of : A) high temperature and high pressure B) high temperature and low pressure C) low temperature and high pressure D) low temperature and low pressure 7) Automobile air bags use the decomposition of sodium azide as their source of gas for rapid inflation: 2NaN3 (s) → 2Na (s) + 3N2 (g). What mass (g) of NaN3 is required to provide 40.0 L of N2 at 25.0°C and 763 torr? A) 1.64 B) 1.09 C) 71.1 D) 160 8) The work done (J) by the reaction in the above question (6) is: A) 4069 B) 6049 C) 9460 D) 9604 9) In an isothermal process, one mole of an ideal gas expanded reversibly, at 27 oC, from V1 = 20 L to V2 = 30 L. The heat absorbed by the gas in this process, in J, is: A) 557 B) 1011 C) 1396 D) 1729 10) One mole of an ideal gas (γ = 1.4) is expanded reversibly and adiabatically from V1 = 15 L to V2 = 45 L. If the initial pressure was 2.00 atm, then the final pressure, in atm, will be: A) 0.76 B) 0.61 C) 0.51 D) 0.43