Exam3FormA - Chemistry 12 Exam III Form A April 4, 2001 Name

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Unformatted text preview: Chemistry 12 Exam III Form A April 4, 2001 Name ____________________ Section ____________________ Student No. ____________________ IMPORTANT: On the scantron (answer sheet), you MUST clearly fill your name, your student number, section number, and test form (white cover = test form A; yellow cover = test form B). Use a #2 pencil. In all questions involving gases, assume that the ideal-gas laws hold, unless the question specifically refers to the non-ideal behavior. ___________________________________________________________________________ 1. It takes 21.3 s for N2 (g) to effuse from a 1.0 L container at 30 oC. In a separate experiment, it takes 25.4 s for an unknown gas to effuse under identical conditions. Which of the following gases can be the unknown gas? a. b. c. d. e. Cl2 O2 Kr Ar Ne ___________________________________________________________________________ 2. If a 20.0 L sample of NH3 (g) at STP is dissolved in methanol to yield a total volume of 845 mL, what is the molarity of the resulting NH3/methanol solution? a. b. c. d. e. 1.06 M 0.947 M 10.6 M 9.47 M 16.9 M _____________________________________________________________________________ There are 26 questions on this exam. Check that you have done all of the problems and filled in the first 26 bubbles on the scantron. The maximum score on this exam is 20 points. Exam policy • • • • Calculators with text-programmable memory are not allowed. Relevant data and formulas, including the periodic table, are attached at the end of this exam. Your grade will be based only on what is on the scantron form. The answer key will be posted on the web after the exam (under "News"). • a. b. c. d. e. N S C Cl F ______________________________________________________________________________ 4. How many electron-pair domains are around the central atom of NH3? Hints • 3. Which of the following elements is primarily responsible for the photochemical smog? As you read the question, underline or circle key words to highlight them for yourself. Avoid errors from "misreading" the question. There is no penalty for guessing. a. b. c. d. e. 1 2 3 4 5 ______________________________________________________________________________ 1 2 ___________________________________________________________________________ ______________________________________________________________________________ 5. In which of the following species does the central atom obey the octet rule? 9. CFC’s are responsible for ozone depletion in the atmosphere. The process of depletion of O3 begins with the photodissociation of carbon-chlorine bonds in the CFC’s. If the typical C-Cl bond energy in CFC’s is 328 kJ/mol, what is the minimum wavelength of light needed to break this bond? a. b. c. d. e. SF4 XeF2 BrF5 ClF3 CCl3– ______________________________________________________________________________ 6. Which of the following gases has a density of 4.42 g/L at 125 oC and 714 torr? a. b. c. d. e. 453 nm 426 nm 398 nm 365 nm 274 nm ______________________________________________________________________________ a. b. c. d. e. H2 CH4 He O3 CCl4 10. What are the electron-pair and the molecular geometries of SnCl3–? electron-pair ______________________________________________________________________________ 7. A study of the effects of certain gases on plant growth requires a synthetic atmosphere. Such an atmosphere was prepared by mixing 3.00 moles of CO2(g), 36.0 moles of O2(g), and 161 moles of Ar(g). What is the partial pressure of O2(g), if the total pressure of this synthetic atmosphere is 745 torr? a. b. c. d. e. trigonal pyrimidal trigonal planar tetrahedral tetrahedral trigonal planar tetrahedral trigonal pyramidal tetrahedral trigonal pyramidal trigonal planar ___________________________________________________________________________ 11. In a certain sample of air, the argon concentration is found to be 9340 ppm. What is the partial pressure of Ar, if the total pressure is 737 torr? 0.980 atm 1.76 atm 134 torr 20.7 torr 41.4 torr ______________________________________________________________________________ 8. Which of the following statements based on the kinetic theory of gases is true? a. b. c. d. e. a. b. c. d. e. molecular At a given temperature, different gases have different average kinetic energy. At a given temperature, different gases have the same average kinetic energy. At a given temperature, different gases have the same root-mean-square speeds. At a given temperature, all molecules of a given gas have the same speed. As the temperature of the gas increases, the volume of that gas must increase, because molecules need more space to keep the number of collisions constant. a. b. c. d. e. 6.88 torr 68.8 torr 7.89 torr 12.7 torr 127 torr ____________________________________________________________________________ 12. What is the molecular shape and polarity of SF4? a. b. c. d. e. trigonal bipyramidal, nonpolar trigonal pyramidal, polar seesaw, polar T-shaped, polar tetrahedral, nonpolar ______________________________________________________________________________ _____________________________________________________________________________ 3 4 ___________________________________________________________________________ ___________________________________________________________________________ 13. Based on average bond energies, what is ∆Hrxn for the following reaction? 17. Which of the following compounds is the most polar? C-C C-H C-Cl H3C C 348 kJ/mol 413 kJ/mol 328 kJ/mol C CH2 CH2OH C=C C-O O-H + 614 kJ/mol 358 kJ/mol 463 kJ/mol C≡C 839 kJ/mol Cl-Cl 242 kJ/mol O-Cl 222 kJ/mol H3C CCl2 CCl2 CH2 CH2OH 2Cl2 a. b. c. d. e. XeF4 CF4 SF4 SiF4 GeF4 ___________________________________________________________________________________ a. b. c. d. e. –562 kJ/mol +562 kJ/mol –685 kJ/mol +11 kJ/mol –337 kJ/mol 18. Referring to the mercury manometers below, which of the following statements about the pressure of the gas inside the container (expressed in mm Hg) does not have to be true? ____________________________________________________________________________ 14. What is the hybridization of the six carbons in benzene? a. b. c. d. e. all are sp6 hybridized all are sp3 hybridized all are sp2 hybridized all are sp hybridized they have alternating sp2 and sp3 hybridization __________________________________________________________________________ 15. What is the rms speed (in m/s) of carbon tetrachloride (CCl4) molecules at 22 ˚C? a. b. c. d. e. 6.96 219 4.83x104 156 478 ______________________________________________________________________________ ______________________________________________________________________________ 16. In which of the following species, does the central atom not obey the octet rule? a. b. c. d. e. a. In set up # 1, the pressure of the gas is greater than the atmospheric pressure. b. In set up # 2 the pressure of the gas is less than atmospheric pressure. c. In set up # 3, the pressure of the gas is greater than the atmospheric pressure by h3. d. In set up # 1, the pressure of gas is equal to the difference in the heights of the mercury levels in the two arms (h1). e. In set up # 2, the pressure of the gas is equal to Patm – h2, where h2 is in mm Hg SCl2 CO32– CN– NO3– ClO2 ______________________________________________________________________________ 5 19. How many additional moles of argon must be added to a flask containing 2.00 moles of argon at 25 oC and 1.00 atm pressure in order to increase the pressure to 1.60 atm under conditions of constant temperature and volume? a. 0.80 b. 1.00 c. 1.20 d. 2.20 e. 2.80 ___________________________________________________________________________ 6 ___________________________________________________________________________ ___________________________________________________________________________ 20. Acetylene gas, C2H2(g), was produced (according to the reaction below) from 0.158 g of CaC2, and it was collected over water at 23 oC. The vapor pressure of water at this temperature is 21 torr. The total pressure of the collected gas was 726 torr. What volume does acetylene occupy under these conditions? 24. What kind of orbitals overlap to form the σ C-C bond in ethane (H3C-CH3)? CaC2(s) + 2H2O(l) ! Ca(OH)2 (s) + C2H2(g) a. b. c. d. e. 32.3 mL 64.6 mL 50.4 mL 121 mL 12.1 mL 21. Of the following species, which one has the sp2-hybridized central atom? PH3 CO32– ICl3 I3– SF6 25. In its initial state a sample of argon occupies a 5 L flask at 0 oC. This sample is completely transferred to a 10 L flask, and then the gas is heated to 273 oC. What is the final pressure, when the final temperature is reached? a. b. c. d. e. the final pressure is half of the initial pressure the final pressure is twice the initial pressure the final pressure is R (gas constant) times the initial pressure the final pressure is 4 times the initial pressure the final pressure is equal to the initial pressure _____________________________________________________________________________ _____________________________________________________________________________ 22. How many σ and π bonds does carbon atom form in H-C≡N molecule? a. b. c. d. e. a p orbital and an sp3 orbital an s orbital and a p orbital two p orbitals two sp3 orbitals two sp2 orbitals ______________________________________________________________________________ ______________________________________________________________________________ a. b. c. d. e. a. b. c. d. e. 4 π, no σ 1 σ and 3 π 2 σ and 2 π 3 σ and 1 π 4 σ, no π 26. Which of the following gases would be most likely to exhibit ideal-gas behavior? a. b. c. d. e. He at 1 atm and 10 K Ne at STP Ar at 10 torr and 400 K Ne at 100 atm and 273 K Ar at 50 atm and 100 K ______________________________________________________________________________ ______________________________________________________________________________ END OF EXAM 23. The van der Waals equation, [P + n2a/V2][V – nb] = nRT, accounts for deviations from the ideal gas behavior. Which term in the equations corrects for molecular volume? a. b. c. d. e. n T V nb n2a/V2 _____________________________________________________________________________ 7 8 Constants & Equations PERIODIC TABLE of the ELEMENTS (2001) 1 J = 1 kg· m2·s-2 RH = 2.18 × 10-18 J c = 3.00 × 108 m·s-1 e = –1.60 × 10-19 C h = 6.63 × 10-34 J·s 1 D = 3.33 × 10-30 C·m MAIN GROUPS H 1.008 3 8A 18 2 R = 8.314 J/(mol·K) R = 0.08206 L·atm/(mol·K) R = 1.987 cal/(mol·K) 11 4.003 F Ne 12.011 14.007 15.999 18.998 20.180 C N O 10 13 Mg 24.305 20 6B 6 24 7B 7 25 3B 3 21 4B 4 22 5B 5 23 V Cr Mn 47.867 50.942 51.996 54.938 K Ca Sc 39.098 40.078 44.956 Ti 1 mol of gas at STP occupies V = 22.41 L 14 15 16 S Cl Ar 26.982 28.086 30.974 32.066 35.453 39.948 58.693 Cu Zn Ga Ge As Se Br Kr 63.546 65.39 69.723 72.61 74.992 78.96 79.904 83.80 45 46 35 36 Zr Nb Mo Tc Ru Rh Pd Ag Cd 48 49 In Sn Sb Te 52 53 I Xe 92.906 95.94 [98] 101.07 102.90 106.42 107.87 112.41 114.82 118.71 121.76 127.60 126.90 131.29 Cs Ba La* Hf Ta 73 74 W Re Os 76 77 Ir Pt Au Hg 80 81 Tl Pb Bi Po At Rn 137.33 138.91 178.49 180.95 183.84 186.21 190.23 192.22 195.08 196.97 200.59 204.38 207.2 208.98 [209] [210] [222] 84 85 86 Fr (P + n a/V )(V - nb) = nRT d= PM/(RT) PV = nRT c = λν E = hν 1 1 ∆E = R H 2 − 2 n nf i E = kLQ1Q2/d q = m · c · ∆T Pi = Xi Ptot Ra Ac** 89 104 105 106 107 108 109 110 111 112 114 116 118 [223] [226] [227] [261] [262] [266] [264] [265] [268] [269] [272] [277] [285] [289] [293] Rf Db Sg Bh Hs Mt λ = h/mv µ=Qr 88 83 54 132.91 87 82 51 34 18 91.224 79 50 33 17 Y 78 47 32 P 39 75 44 31 Si 88.906 72 43 58.933 Al 38 57 42 Ni 55.845 1B 11 29 Sr 56 41 Co 8B 10 28 87.62 55 40 Fe 8B 9 27 8B 8 26 Rb 2 u= 7A 17 9 2B 12 30 12 Na 37 6A 16 8 B TRANSITION METALS 22.990 19 5A 15 7 10.811 Be 9.012 4A 14 6 85.468 1 atm = 760 mmHg = 760 torr 1 atm = 1.01325 × 105 Pa 1 atm = 1.01.325 kPa 2 Li He 3A 13 5 2A 2 4 6.941 N = 6.02 × 1023 mol-1 MAIN GROUPS 1A 1 1 r1 = r2 3RT M M2 M1 ∆H°rxn = Σ n ∆H°f (products) − Σ m ∆H°f (reactants) ∆H°rxn = Σ (∆H of bonds broken) − Σ (∆H of bonds formed) 9 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 140.12 * LANTHANOIDS 140.91 144.24 [145] 150.36 151.96 157.25 158.92 162.50 164.93 167.26 168.93 173.04 174.97 90 ** ACTINOIDS Th Pa 91 92 U Np Pu Am Cm Bk Cf Es Fm Md 101 102 103 232.04 321.04 238.03 [237] 93 [244] 94 [243] 95 [247] [247] [251] [252] [257] [258] [259] [262] 10 96 97 98 99 100 No Lr ANSWER KEY Chem 12 Exam III Spring 2001 1. D 2. A 3. A 4. D 5. E 6. E 7. C 8. B 9. D 10. D 11. A 12. C 13. E 14. C 15. B 16. E 17. C 18. A 19. C 20. B 21. B 22. C 23. D 24. D 25. E 26. C 11 ...
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This note was uploaded on 05/24/2009 for the course CHEM 110 taught by Professor Hofmann,brucerob during the Fall '08 term at Pennsylvania State University, University Park.

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