Exam%202%20F2008%20(PRACTICE)

Exam%202%20F2008%20(PRACTICE) - __________ NAME (Please...

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Unformatted text preview: __________ NAME (Please PRINT) C102A Examination 2 Fall, 2008 I pledge on my honor that I have neither given nor received improper aid on this examination. Werner Heisenberg (1901–1976) ______________________________ (Signature) Directions: 1. No books or notes may be using during this test. There should be no data stored on your calculator for use on the exam. This includes but is not limited to periodic tables and chemical equations and formulas. 2. There are a total of 1 0 sections (some with several parts) for a sum of 100 points. 3 Be certain that, wherever applicable, you show your work. Problems in sections 5-10 that are answered without showing work will not receive c redit. 4. Please note: there are no intentionally misleading questions on this test. Each problem should be taken at its face value. You must, however, be certain to read each problem carefully! 5. If you have any questions please ask your professor. DO NOT REMOVE THIS PAGE FROM YOUR EXAM!!!!! Please be sure that you are officially enrolled in the section named below: Section 2–Hanusa Exam Score________ 2 SECTION 1 1. TRUE OR FALSE (15 PTS. TOTAL; 3 PTS. EACH) ) Circle either True or False for each answer. (a) Enthalpy, H, and heat, q, are both state functions. True False (b) The energy of an electron in the first Bohr orbit of Li2+ ion is lower than that of a H atom. True False (c) The electron configuration for the nitrogen atom is [Ne]3s23p3. True False (d) An electron in a 4f orbital can have the quantum numbers of n = 4, l = 2, ml = -2 and ms = 1/2. True False True False (e) Communication waves used in cell phones have longer wavelengths than the sun rays used to tan the skin. SECTION 2 MULTIPLE CHOICE (21 PTS. TOTAL; 3 PTS. EACH) Pick the one best answer; if you circle more than one, you will receive NO credit! (1) The transition of an electron, in a hydrogen atom, from n = 4 to a lower level results in the emission of light of wavelength 1876 nm. The principal quantum number for that lower level is: (a) 0 (b) 1 (c) 2 (d) 3 (e) None of these (2) Photosynthesis in plants uses 5645 kJ of energy to produce one mol of sucrose (C12H22O11) If sunlight supplies 1 kJ energy per second, then the number of hours of sun light needed to produce 109 g sucrose via photosynthesis is: (a) 1 hr (b) 24 hrs (c) 0.5 hr (d) 1799 hrs (e) None of these (3) A Styrofoam cup calorimeter has a heat capacity of 84.5 J/K. When a certain amount of NH4NO3(s) is dissolved in 100.0 g of water in the calorimeter at 25 oC, the temperature inside calorimeter dropped to 22.93 oC. The heat absorbed by the dissolution reaction must be: (a) 175 J (b) 866 J (c) 691 J (d) 1041 J (e) None of these 3 (4) Rank the x-rays, radio waves, infrared, ultraviolet regions of electromagnetic radiation in order of increasing energy: (a) x-rays < radio waves < infrared < ultraviolet (b) ultraviolet < infrared < radio waves < x-rays (c) x-rays < ultraviolet < infrared < radio waves (d) radio waves < infrared < ultraviolet < x-rays (e) none of these (5) When 100 g of water was heated in a microwave oven (that is emitting microwaves of 1 cm wavelength), the temperature of water rose from 25 oC to 85 oC. The number of microwave photons emitted for heating the water must be: (a) 2.10x105 mol (b) 2.10x103 mol (c) 1.30x103 mol (d) 2.51x104 mol (e) None of these (6) Breaking of the chemical bonds in an N2 molecule requires 941 kJ/mol. What is the longest wavelength of radiation that is required to break the chemical bonds in N2? (a) 127 nm (b) 786 nm (c) 270 nm (d) 400 nm (e) None of these (7) Ionization energy is the energy needed to detach an electron from an atom/ion. Based on the energies given in the Bohr model for one electron atom/ion, the energy needed to detach electron from n = 1 levels of H atom and Be3+ ion compare as: (a) energy needed to detach electron of H atom is greater than that of Be3+ (b) energy needed to detach electron of H atom is less than that of Be3+ (c) energy needed to detach electron of H atom is same as that of Be3+ (d) cannot be predicted (e) none of these 4 SECTION 3 (12 PTS.; 2 PT. Each) Match the following with the best possible answer. 1. Heat measured for chemical reactions in a constant pressure calorimeter equals _____ 2. The energy needed to detach an electron from n = 1 level of H atom is: ______ 3. An atom with electron configuration of [Ne]4s23d1 : _______ 4. The specific heat capacity of aluminum is 0.900 J g-1 K-1. Then molar heat capacity of aluminum must be ______ 5. The de Broglie wavelength is: ________ 6. The number of unpaired electrons in the electron configuration of S atom is: ________ (A) -∆Erxn (B) 2.18x10-18 J (C) K (D) 30.0 J.mol-1•K-1 (E ) 1 n m (F) 8.72x10-18 J (G) λ = h/mv (H) q+w (I) ∆Erxn (J) λ = mv (K) Sc (L) 1 (M) 4.36x10-18J (N) 24.3 J•mol-1•K-1 (O) λ = mv/h (P) 2 (Q) ∆Hrxn (R) does not exist (S) 3 (T) 0.033 J. mol-1•K-1 (U) Ca (V) none of the above 5 SECTION 4 (12 PTS.; 2 PT. Each) In the center column, write “>”, “<”, “ = ”, or “?” (can’t tell) to describe the relationship between the following quantities. The first one has been done for you. # of Chem. 102a students. > # of Chem. 102a teachers. a. De Broglie wavelength for an electron traveling at 106m/s. De Broglie wavelength for a 100 g baseball traveling at the same speed. b. The number of orbitals in a sub shell with n = 3 and l = 2. The number of orbitals in a sub shell with n = 4 and l = 2. c. Final temperature of the surroundings, initially at 25 oC, following an exothermic reaction Final temperature of the same surroundings, initially at 25 oC, following an endothermic reaction d. Wavelength of light emitted from n = 2 to n = 1 transition in H atom Wavelength of light emitted from n = 3 to n = 2 transition in H atom e. Specific heat capacity of a hot metal at 60 oC which, when equilibrated with 100 g water at 25 oC, increases the temperature of water by 2 oC. Specific heat capacity of a hot metal at 60 oC which, when equilibrated with 100 g water at 25 oC, increases the temperature of water by 10 oC. f. The energy of 4s orbital in K atom The energy of 3d orbitals in K atom 6 SECTION 5 (5 PTS.) Credit will not be given if detailed step-by-step work is not shown Suppose 1 mg propane (C3H8; MW = 44.1) and enough O2(g) for a complete reaction, are placed in a sealed constant volume reaction vessel. This reaction vessel is placed inside a 4.0 L container with N2(g) and equipped with a piston that can move freely against an external pressure of 1 atm. The following reaction was allowed to occur in the reaction vessel: C3H8(g) + 5 O2(g) 3 CO2(g) + 4 H2O(g) ∆Erxn = -2217 kJ If all of the heat generated in the reaction vessel is transferred to N2(g) in the outside container, and was used by N2(g) for P-V work, then what should have been the volume of the outside container at the end of reaction? Final volume (in L): SECTION 6 (10 PTS.) Credit will not be given if detailed step-by-step work is not shown The decomposition of liquid trinitroglycerin, C3H5N3O9 (MW = 227.1), at 1 atm pressure and 25 oC results in production of nitrogen gas, carbon dioxide gas, liquid water and oxygen gas. The enthalpy of decomposition for 100 g trinitroglycerin is -679.0 kJ. Determine the enthalpy of formation of trinitroglycerin. For useful information, see page 9 (with periodic table) Enthalpy of formation of trinitroglycerin in kJ/mol: 7 SECTION 7 (6 PTS.) Credit will not be given if detailed step-by-step work is not shown. The red color that we see in fireworks is attributed to emission from strontium ions. If we were to produce the same color (wavelength = 656 nm) from H atoms, the emission between which successive levels of H atom will produce this color? n= to n= SECTION 8 (5 PTS.) Credit will not be given if detailed step-by-step work is not shown. (1) C2H2 (g) + (5/2) O2(g) (2) C(s) + O2 (g) (3) H2O(l) ∆H = -1296.6 kJ 2CO2(g) + H2O(l) ∆H = -393.5 kJ CO2(g) ∆H = +285.8 kJ H2(g) + ½ O2(g) Calculate H for the reaction, 2C(s)+ H2(g) C2H2(g) Indicate the manipulation(s) needed for reaction (1): Indicate the manipulation(s) needed for reaction (2): Indicate the manipulation(s) needed for reaction (3): Enthalpy of reaction: 8 SECTION 9: (6 pts) Credit will not be given if detailed step-by-step work is not shown. The binding energy of electrons in a metal is 8x10-19 J. (a) What will be the kinetic energy of the ejected electron when light with a wavelength of 200 nm is shined on to that metal? (4 points) Kinetic Energy (in J): (b) What is the threshold frequency below which the electron will not be ejected in (a)? (2 points). Frequency (in s-1): SECTION 10 (8 PTS.) (a) Write the electron configuration for chlorine atom (2 pts). (b) Identify the valence electrons in chlorine atom (1 pt). (c) Identify the core electrons in chlorine atom (1 pt). (d) Fill the following table (4 points): orbital Number of radial Number of angular nodal nodes planes 3s 3d 9 CONSTANTS: R = 0.08206 L atm/mol K = 8.314 J/mol K; Avogadro’s number = 6.022 × 1023 1 atm = 760 torr = 101,325 Pa; CH2O = 4.184 J/(g.oC) = 1 cal/(g•oC) Planck’s constant = 6.626x10-34 J•s; Rydberg constant = 2.18 × 10-18 J; velocity of light = 3.00 x 108 m/s; mass of electron = 9.10938262 × 10-31 kg ∆Hf(CO2(g)) = -393.5 kJ/mol; ∆Hf(H2O(l)) = -285.8 kJ/mol. 1 1 H H 1.00794 3 4 Li Be 6.941 11 9.01218 Na 5 Mg 22.98977 19 Ca K 39.0983 37 40.078 85.4678 87.62 55 Sc Ti 23 V 24 Cr 44.95591 39 47.867 40 50.9415 41 51.9961 88.90585 57 95.94 56 132.90545 137.327 138.9055 87 88 38 Rb Cs Fr (223) Sr Ba Ra (226) Y La 89 Ac (227) Zr 42 91.224 Nb 92.90638 Mo 72 73 74 Hf Ta W 25 Mn A ctinide s Fe 27 Co 28 Ni 29 Cu 55.845 44 58.93320 45 58.6934 46 63.546 47 (98) 75 101.07 76 102.9055 77 106.42 107.8682 79 Tc Re Ru Os Rh Ir 178.49 180.9479 183.84 186.207 190.23 192.217 104 105 106 107 108 Pd 78 Pt 12.0107 14.0067 15.9994 18.99840 14 15 16 17 Ag Au (261) Db (262) Sg (263) Bh (262) 59 60 61 Ce Pr Nd 144.24 Pm (145) 90 91 92 93 Th Pa U Np 140.116 140.90765 232.0381 231.0359 238.0289 (237) Hs Zn 65.39 48 Cd 112.411 80 Hg 63 200.59 31 Ga 69.723 49 In 114.818 81 Tl 204.3833 P 32 33 28.0855 30.97376 Ge S 32.066 35.4527 34 35 72.61 As 74.92160 Se 50 51 52 Sn 118.710 82 Pb 207.2 Sb 78.96 Te 121.760 127.60 83 84 Bi 208.9804 Cl Po (209) Br (265) 64 95 At Rn (210) 65 66 67 68 69 70 71 158.9253 Dy 162.50 Ho 164.9303 Er 167.26 Tm 168.9342 Yb 173.04 Lu 96 97 98 99 100 101 102 Bk Cf (251) Es Fm (257) (244) (247) (247) (252) Md No (258) (259) 36 Kr 131.29 86 Tb Pu Am Cm (243) 39.948 126.9045 85 I 157.25 94 18 Ar 83.80 (266) Eu Sm 151.964 Gd 150.36 10 79.904 53 Mt 62 196.96655 30 Si 109 Rf 195.078 20.1797 O 13 54.93805 43 58 Lanthanides 26 Ne N 26.98154 22 F C Al 21 1.00794 9 4.002602 8 10.811 24.3050 20 7 B Periodic T le of the Elements ab 12 6 2 He 174.967 103 Lr (262) 54 Xe (222) ...
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This note was uploaded on 01/10/2010 for the course CHEM 102a taught by Professor Hanusa during the Spring '06 term at Vanderbilt.

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