15772_e_8888

15772_e_8888 - PROF ROBERT ANGELICI FALL 2003 THIS EXAM...

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Unformatted text preview: PROF. ROBERT ANGELICI FALL 2003 THIS EXAM CONSISTS OF 10 QUESTIONS ON 6 PAGES GRADING POINTS 26 pts 29 pts 20 pts 25 pts 100 pts CHEM 167 HOUR EXAM I SEPTEMBER 16, 2003 NAME______________________ RECIT. INSTR._______________ RECIT. SECT.________________ PAGES Page 2 Page 3 Page 4 Page 5 TOTAL SCORE ________ ________ ________ ________ ________ Teaching Assistants and Recitation Sections Name Sections Time Jonathan Bentz 7, 12 12:10, 3:10 Supratim Giri 4, 6 10:00, 12:10 Hyunjin Ko 16, 20 10:00, 2:10 Becky Li 3, 8 9:00, 1:10 Rajeswari Mani 2, 17 9:00, 11:00 Michael Mitchell 5, 19 10:00, 1:10 Jareer Oweimrin 1, 10, 11 8:00, 1:10, 2:10 Kale Swainston 13, 15 8:00, 9:00 Marlen Valverde 9, 23 1:10, 4:10 Molly Warnke 14, 22 9:00, 3:10 Jack Yan 18, 21 12:10, 2:10 Rules for the Exam: 1. Show all of your work on these exam pages. Numerical answers should be given in the correct number of significant figures and units. Put your answers in the answer spaces. 2. The last page contains useful information and a periodic table. THE ANSWER KEY TO THIS EXAM WILL BE POSTED ON BULLETIN BOARD #4 IN THE HALLWAY EAST OF ROOM 1002 GILMAN AND ON THE CHEM 167 WEBSITE. THE LAST DAY TO DROP CHEM 167 AND ADD CHEM 155 IS WEDNESDAY, SEPTEMBER 24, AT 5:00 P.M. SEE YOUR ADVISOR TO OBTAIN THE DROP/ADD FORM AND COME TO THE GENERAL CHEMISTRY OFFICE, ROOM 1608 GILMAN HALL. 2 1. (26 pts) Aluminum metal reacts with MnO according to the following balanced equation: 2 Al + 3 MnO Æ Al2O3 + 3 Mn The reaction is carried out using 1.10 ¥ 102 g of Al and 2.00 ¥ 102 g of MnO. A. (4 pts) How many moles of Al are used? Answer_________________________ B. (4 pts) How many atoms of Al are used? Answer_________________________ C. (7 pts) After the reaction is complete, which reactant is in excess? How many moles excess? Answer_________________________ D. (6 pts) How many grams of Mn are formed in the reaction? Answer_________________________ E. (5 pts) If 10.0 g of Mn is actually obtained after separating it from the Al2O3, what is the percent yield of Mn? Answer_________________________ 3 2. (5 pts) You want to sell a compound which, when mixed with water, feels cold. The compound with water could be used as a cold-pack. Which one of the following properties must the compound have? a) The heat of formation (∆H o ) of the compound must be negative. f b) The heat of reaction (∆Hrxn) of the compound with H2O must be negative. † c) The heat of formation (∆H o ) of the compound must be positive. f d) The heat of reaction (∆Hrxn) of the compound with H2O must be positive. † e) None of the above. 3. (12 pts) A roll of 83.0 g of Cu wire heated to 100.0 ˚C is added to 38.3 g of water initially at 20.5 ˚C. The final temperature of the wire and the water is 33.8 ˚C. What is the specific heat of Cu? Answer_________________________ 4. (12 pts) A 1.00 g sample of octane (C8H18) reacts with excess O2 in a bomb calorimeter according to the following balanced equation: C8H18(l) + 25 O2(g) Æ 8 CO2(g) + 9 H2O(l) 2 The temperature of the calorimeter, containing 1.20 kg of water, increases from 25.00 ˚C to 33.20 ˚C when the reaction occurs. If the heat capacity of the calorimeter is 837 J/˚C, what is qrxn (in kJ) for the reaction? † Answer_________________________ 4 5. (10 pts) Calculate the heat (enthalpy) of combustion (in kJ/mol) of C2H4(g), C2H4(g) + 3 O2(g) Æ 2 CO2(g) + 2 H2O(l) given the following standard enthalpies of formation: compound H2O(l) CO2(g) ∆H o , kJ/mol f –285.8 –393.5 compound CO(g) C2H4(g) ∆H o , kJ/mol f –110.5 +51.8 Answer_________________________ † † 6. (10 pts) How many mL of 0.25 M HCl are required to react with 1.00 g of Mg metal according to the following balanced equation: Mg + 2 HCl Æ MgCl2 + H2 Answer_________________________ 5 7. (6 pts) Correctly name the following compounds: A. SnS Answer B. NH4NO3 Answer 8. ___________________________________________________ ___________________________________________________ (6 pts) Write correct formulas for the following: A. sodium phosphate Answer _______________________ B. copper(II) carbonate Answer 9. _______________________ (9 pts) Calculate the empirical formula of a compound containing 52.9% carbon and the rest is oxygen. Answer_________________________ 10. (4 pts) What is the oxidation number of the underlined atom in the following? A. C2H6O B. B3O63– __________ __________ 6 Information Avogadro’s Number = 6.02 ¥ 1023 4.18 J/g ˚C q = ms∆t Periodic Table of the Elements 1A 1 1 H 1.01 3 Li 6.94 11 Na 23.0 19 K 39.1 2A 2 3A 13 5 B 10.8 10 1B 11 29 Cu 63.5 47 Ag 108 79 Au 197 2B 12 30 Zn 65.4 48 Cd 112 80 Hg 201 13 Al 27.0 31 Ga 69.7 49 In 115 81 Tl 204 4A 14 6 C 12.0 14 Si 28.1 32 Ge 72.6 50 Sn 119 82 Pb 207 8A 18 2 5A 6A 7A He 15 16 17 4.00 9 10 7 8 F Ne N O 14.0 16.0 19.0 20.2 18 15 16 17 Ar P S Cl 39.9 31.0 32.1 35.4 36 33 34 35 Kr As Se Br 74.9 79.0 79.9 83.8 54 51 52 53 Xe Sb Te I 122 128 127 131 85 86 83 84 At Rn Bi Po 209 (209) (210) (222) 4 Be 9.01 12 Mg 24.3 20 Ca 40.1 37 38 Rb Sr 85.5 87.6 55 56 Cs Ba 133 137 87 88 Fr Ra (223) 226 8B 3B 3 4B 4 5B 5 6B 6 7B 7 25 Mn 54.9 43 Tc (98) 75 Re 186 107 Uns (262) 8 26 Fe 55.8 9 21 22 23 24 Sc Ti V Cr 45.0 47.9 50.9 52.0 39 40 41 42 Y Zr Nb Mo 88.9 91.2 92.9 95.9 57 72 73 74 La Hf Ta W 139 178 181 184 89 104 105 106 Ac Rf Ha Unh 227 (261) (262) (263) 27 28 Co Ni 58.9 58.7 44 45 46 Ru Rh Pd 101 103 106 76 77 78 Os Ir Pt 190 192 195 108 109 Uno Une (265) (266) Lanthanides Actinides 58 Ce 140 90 Th 232 59 Pr 141 91 Pa 231 60 61 62 63 64 65 66 67 68 69 70 71 Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 144 (145) 150 152 157 159 162 165 167 169 173 175 92 93 94 95 96 97 98 99 100 101 102 103 U Np Pu Am Cm Bk Cf Es Fm Md No Lr 238 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) (260) ...
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This note was uploaded on 12/10/2009 for the course CHEM 1111 at Colorado.

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