CHEM 1201 Sect 03 EXAM 4 Chapters 9 & 10 Spring 2014 Dr. Kolniak FORM 1 If you have a question about the content of any of the problems or the answers provided, raise your hand. Make sure that every problem has an answer bubbled in on the scantron and DOUBLE check your answers on the scantron. Bubble in your FORM # in the Grade or Education Box. Select the very very best answer (5 pts each). Useful information: WATCH UNITS! Gas constant, R = 0.0821 L-atm/mol-K or 8.314 kg-m2/s2-K-mol 1 atm = 760 torr = 760 mmHg T(K) = 273 + C 1. A sample of a gas mixture with a total pressure of 5.2 atm contains 0.85 moles of N2, 3.2 moles of H2, and 1.9 moles of O2. What is the partial pressure of O2 in the sample? a. b. c. d. e. 2.74 atm 1.66 atm 0.89 atm 9.88 atm 2.80 atm 2. Which compound(s) is/are an/a NONPOLAR species? a. HCl b. Br2 c. SO3 d. NO2e. Both b & c are nonpolar 3. What is the Molecular Geometry around each C atom in the C2H4 molecule? a. b. c. d. e. Trigonal planar Tetrahedral T-shaped Trigonal pyramid Linear 4. For the CO3-2, the electronic domain geometry is ________________ and the molecular geometry is _________________. a. tetrahedral, trigonal pyramid b. tetrahedral, trigonal planar c. trigonal planar, trigonal planar d. trigonal planar, trigonal pyramid e. trigonal pyramid, trigonal pyramid 5. You inflate a balloon with 500 ml of H2 at a temperature of 25C and you warm it up carefully to 30C. You noticed that the volume of the balloon has changed. Assuming the pressure and moles of gas remains constant; calculate the “new” volume, in Liters, of the balloon at 30C. a. b. c. d. e. 0.75 L 0.49 L 0.42 L 0.60 L 0.51 L 6. Consider the following molecule. What is the hybridization around the following atoms indicated below? a b c d e C1 sp sp2 sp3 sp2 sp2 C2 sp3 sp3 sp3 sp3 sp2 O1 sp2 sp3 sp2 sp2 sp3 7. What is the rate of effusion of O2 compared to Ne? a. b. c. d. e. 1.26rNe 0.79rNe 0.63rNe 1.60rNe 0.85rNe 8. Determine the volume in liter’s for a 14 g of N2 gas sample at a pressure of 1050 torr and a temperature 45˚ C. a. b. c. d. e. 18.9 L 0.01 L 0.14 L 9.44 L 0.05 L 9. Determine the temperature in K for a 2.0 mole gas sample contained in a sealed 50.0 Liter tank at a pressure of 2250 torr. a. b. c. d. e. 90 K 50 K 298 K 450 K 901 K 10. Calculate the rms velocity for O2 gas at a temperature of 350 K. a. b. c. d. e. 522 m/s 52.2 m/s 1.64 m/s 2728 m/s 243 m/s 11. In the structure shown below, which are the correct hybridizations? I. The hybridization of C1 is sp. II. The hybridization of C2 is sp2. III. The hybridization of S is sp. a. I only. b. II only. c. III only d. I and II only e. All are correct. 12. Which statement is correct for the H – B – H angles in BH3 and H–C–H angles in CH4? Note: Approximately does not mean exactly. a. The angle in BH3 is approximately 120°. b. The angle in CH4 is approximately 120°. c. The angle in BH3 is approximately 109.5°. d. The angle in CH4 is approximately 90°. e. Both a & b are correct. 13. Consider the below apparatus. The containers are sealed from the outside world and the gas samples are contained at the same temperature. When the valve between the three containers is opened and the gases are allowed to mix. What is the TOTAL pressure after mixing?! Ar Ne 3.0 L 8.0 atm 2.0 L 6.0 atm He 2.0 L 5.0 atm a. b. c. d. e. 2.19 atm 6.33 atm 6.57 atm 5.45 atm 2.71 atm 14. Calculate the density, g/L, of CO under the conitions of 765 torr and 350 K. a. b. c. d. e. 2.26 g/L 4.52 g/L 2.58 g/L 3.63 g/L 4.15 g/L 15. Which of the following is/are polar? I. CCl4 II. CH3F III. H2O IV. ClF3 V. CO2 a. I & IVonly b. II only c. II & III only d. II, III & IV only e. I & V only 16. What are the types of bonds and how many are found around the atom labeled O1? O H H H N C C1 O1 H H a. b. c. d. e. 1 sigma bond 2 sigma bonds 2 sigma bond and 2 pi bond 3 sigma bond and 2 pi bonds 2 pi bonds 17. A sample of gas is confined to a cylinder housed with a movable piston. The gas occupies a volume of 1.2 L at 2.0 atm and 35C. Calculate the volume of the gas sample if the pressure is increased to 18 atm at constant temperature. a. b. c. d. e. 0.13 L 7.50 L 1.33 L 0.75 L 5.32 L 18. A sample of gas is confined to a cylinder housed with a movable piston. Initially, the gas occupies a volume of 1.5 L at 2.0 atm and 10C. Calculate the pressure of the gas sample if the volume is increased to 6.0 L and the temperature increased to 25C. a. b. c. d. e. 1.90 atm 0.47 atm 2.11 atm 0.53 atm 1.83 atm 19. In the molecule BrF5, what is the molecular geometry? a. Seesaw b. Square pyramid c. Tetrahedral d. Trigonal bipyramid e. Octahedral 20. A flexible container is filled with 15 moles of a gas and occupies a volume of 18 L. Later, The container loses 7.2 moles of gas. Calculate the final volume . Assuming constant temperature and pressure. a. b. c. d. e. 34.61 L 11.84 L 9.36 L 8.76 L 13.43 L 21. BONUS: How many grams of A (assume molar mass of A is 56 g/mol) are required to react with 8.0 L of B at 100C and 10.2 atm of pressure to form C? 2 A (g) + B (g) 3 C (g) a. b. c. d. e. 149g 75g 557g 298g 1113g

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