Chemistry Exam Study Material, Exams of Chemistry

Download Chemistry Exam Study Material and more Exams Chemistry in PDF only on Docsity! CHEM 1515 Name ________________________ Exam V TA's Name ________________________ John V. Gelder December 14, 1993 Lab Section ________________________ INSTRUCTIONS: 1. This examination consists of a total of 15 different pages. The last umpteen pages include a whole heck of alot of important mathematical equations, constants and tables. All work should be done in this booklet. You may carefully remove the last 5 pages of the examination. 2. PRINT your name, your TA's name and your laboratory section now in the space at the top of this sheet. DO NOT SEPARATE THE PAGES . 3. Answer all questions that you can and whenever called for show your work clearly. Your method of solving problems should pattern the approach used in lecture. You do not have to show your work for the multiple choice or short answer questions. 4. No credit will be awarded if your work is not shown in problems 2 – 6. Please circle your final answer! 5. Point values are shown next to the problem number. 6. Budget your time for each of the questions. Some problems may have a low point value yet be very challenging. If you do not recognize the solution to a question quickly, skip it, and return to the question after completing the easier problems. 7. Look through the exam before beginning; plan your work; then begin. 8. Relax and do well. Page 2 Page 3 Page 4 Page 5 Page 6 TOTAL SCORES _____ _____ _____ _____ _____ ______ (19) (24) (20) (24) (63) (150) CHEM 1515 Exam V – F93 Page 2 (9) 1. Write the chemical formula(s) of the product(s) and balance the following reactions. Identify the phase of each product as either (g)as, (l)iquid, (s)olid or (aq)ueous. Soluble ionic compounds should be written in the form of their component ions. a) HC9H7O4(aq) + NaOH(aq) → b) C3H8(g) + O2(g) → c) Al(s) + Fe2O3(s) → (10) 2. Balance the following oxidation-reduction reaction using the half-reaction method. a) H2O2(aq) + Cr(OH)3(s) → CrO42–(aq) basic solution identify the oxidizing agent ________ identify the reducing agent ________ CHEM 1515 Exam V – F93 Page 5 (14)5a. The mole fraction of ethylene glycol, C2H6O2, in a particular ethylene glycol–water solution is equal to 0.03125. Determine the mass of ethylene glycol in 3.785 L (1 gallon) of this solution if the density of the solution is 1.012 g·mL–1. b. ethylene glycol dissolves in water. Draw a Lewis structure for ethylene glycol which supports this experimental fact. (10)6a. Write the half-reactions and determine the products of the reaction when a piece of sodium metal is added to water at 25 ˚C. b) Is the reaction spontaneous or nonspontaneous? Briefly explain your answer. (Note: You may show a calculation to support your conclusion.) c) If a piece of sodium with a mass 1.00 g is added to 100 mL of water, estimate the pH of the resulting solution. CHEM 1515 Exam V – F93 Page 6 Multiple Choice: (63 points) Print the letter (A, B, C, D, E) which corresponds to the answer selected. 7. ________ 8. ________ 9. ________ 10. ________ 11. ________ 12. ________ 13. ________ 14. ________ 15. ________ 16. ________ 17. ________ 18. ________ 19. ________ 20. ________ 21. ________ 22. ________ 23. ________ 24. ________ 25. ________ 26. ________ 27. ________ ONLY THE ANSWERS IN THE AREA ABOVE WILL BE GRADED. Select the most correct answer for each question. Each question is worth 3 points. 7. ∆G˚ for the reaction BaO(s) + CO2(g) → BaCO3(s) is – at 25 ˚C. Which of the following statements is true? A) The reaction remains spontaneous at higher temperatures. B) The reaction becomes nonspontaneous at higher temperatures. C) The reaction is spontaneous at all temperatures. D) There is not enough information to answer this question. 8. The standard entropy of formation, ∆S˚f of H2O(l) is A) 70 J K B) 406 J K C) –163 J K D) –266 J K 9. A hydrochloric acid solution is 38.0% by mass and it is also 12.5 M. Calculate the density of the solution. A) 0.835 g·mL–1 B) 1.04 g·mL–1 C) 1.20 g·mL–1 D) 1.31 g·mL–1 10. For the half-reaction 2H+(aq) (1.00 x 10–7 M) +2e– → H2(g) (1.00 atm) Ecell is A) +0.829 v B) –0.829 v C) +0.414 v D) –0.414 v CHEM 1515 Exam V – F93 Page 7 11. Which of the following compounds has the greater solubility in water? A) H3C–CH2–CH3 B) CCl4 C) CH2Cl2 D) CH3CH2OH 12. Which of the following solutions will have the lowest freezing point? A) 0.100 M CaCl2 B) 0.100 M NaCl C) 0.100 M C6H12O6 D) 0.100 M NH4NO3 13. Which of the following mathematical relationships would be used to determine the time required for 30% of a reactant to decompose in the first order reaction; A(g) → products A) t = 1.20 k B) t = 0.357 k C) t = 2.33 k·[A0] D) t = 0.428 k·[A0] 14. In the following reaction aA(g) + bB(g) → cC(g) + dD(g) 1.00 mol of A is mixed with 2.00 mol of B in a 1.00 L container at a given temperature. After 10 minutes the concentration of all species were found to be; [A] [B] [C] [D] after 10 min 0.875 M 1.81 M 0.0625 M 0.250 M The balanced chemical equation must be; A) 2A(g) + 3B(g) → C(g) + 4D(g) B) A(g) + 2B(g) → C(g) + D(g) C) A(g) + 2B(g) → C(g) + 4D(g) D) 2A(g) + B(g) → C(g) + D(g) 15. Increasing the temperature in an endothermic reaction will A) increase both the rate of the reaction and the magnitude of the equilibrium constant. B) increase the rate of the reaction and decrease the magnitude of the equilibrium constant. C) decrease the rate of the reaction and increase the magnitude of the equilibrium constant. D) decrease both the rate of the reaction and the magnitude of the equilibrium constant. E) increase the rate and have no affect on the equilibrium constant. CHEM 1515 Exam V – F93 Page 10 Useful Information Equations Constants PV = nRT R = 0.0821 L·atm mol·K = 8.314 J mole.K Psolution = χsolventP˚solvent density of H2O = 1.00 g cm3 ∆T = ikm kf(H2O) = 1.86 ˚C m kb(H2O) = 0.512 ˚C m ∆H˚rxn = ∑(∆Hf˚(products)) – ∑(∆Hf˚(reactants)) ∆S˚rxn = ∑(S˚(products)) – ∑(S˚(reactants)) ∆G˚rxn = ∑(∆Gf˚(products)) – ∑(∆Gf˚(reactants)) ∆G˚ = ∆H˚ - T∆S˚ ∆G˚ = –RT ln K ∆G = ∆G˚ + RT ln Q ∆G˚ = –nFE˚ F = 96,500 Jvolt · mol = 96,500 coulombs Ecell = E˚ – 0.0257 n ln Q E˚ = 0.0257 n ln K Ecell = E˚ – 0.059 n log Q E˚ = 0.059 n log K ln    k1 k2 = Ea R    1 T2 - 1 T1 ln    [A]t [A]o = -kt 1 [A]t - 1 [A]o = kt Kp = Kc(RT)∆n x1,2 = –b± b2 – 4ac 2a for ax 2 + bx + c = 0 pH = –log[H+] Kw = 1.0 x 10–14 pH + pOH = 14 CHEM 1515 Exam V – F93 Page 11 90 232.0 91 231.0 Th Pa 92 238.0 93 237.0 94 (244) 95 (243) 96 (247) U Np Pu Am Cm 97 (247) 98 (251) 99 (252) 100 (257) 101 (258) 103 (260) 102 (259) Bk Cf Es Fm Md LrNo 58 140.1 59 140.9 Ce Pr 60 144.2 61 (145) 62 150.4 63 152.0 64 157.2 Nd Pm Sm Eu Gd 65 158.9 66 162.5 67 164.9 68 167.3 69 168.9 70 173.0 Tb Dy Ho Er Tm Yb 37 85.47 Rb 38 87.62 Sr 39 88.91 Y 40 91.22 Zr 41 92.91 42 95.94 43 (98) 44 101.1 45 102.9 46 106.4 47 107.9 Nb Mo Tc Ru Rh Pd Ag 48 112.4 49 114.8 50 118.7 51 121.8 52 127.6 54 131.3 53 126.9 Cd In Sn Sb Te XeI 3 6.94 4 9.01 Li Be 11 22.99 12 24.30 Na Mg 19 39.10 K 22 47.88 20 40.08 Ca 21 44.96 Sc Ti 23 50.94 24 52.00 25 54.94 26 55.85 27 58.93 28 58.69 29 63.55 V Cr Mn Fe Co Ni Cu 30 65.38 31 69.72 32 72.59 33 74.92 34 78.96 36 83.80 35 79.90 Zn Ga Ge As Se KrBr 5 10.81 6 12.01 B C 8 16.00 O 9 19.00 F 7 14.01 N 10 20.18 Ne 13 26.98 14 28.09 Al Si 16 32.06 S 17 35.45 Cl 15 30.97 P 18 39.95 Ar 2 4.00 He 55 132.9 Cs 56 137.3 Ba 57 138.9 La 72 178.5 Hf 73 180.9 74 183.8 Ta W 75 186.2 76 190.2 77 192.2 78 195.1 79 197.0 Re Os Ir Pt Au 80 200.6 81 204.4 82 207.2 83 209.0 84 (209) 86 (222) 85 (210) Hg Tl Pb Bi Po RnAt 1 1.008 H IA IIA IIIA IVA VA VIA VIIA VIIIA IIBIBVIIIVIIBVIBVBIVBIIIB 1 2 3 4 5 6 7 Lanthanides Actinides Periodic Table of the Elements 87 (223) Fr 88 226.0 Ra 89 227.0 Ac 104 (261) 105 (262) 106 (263) 71 175.0 Lu Rf Db Sg 108 (265) 109 (266) 107 (262) Hs MtBh CHEM 1515 Exam V – F93 Page 12 E.1 DISSOCIATION CONSTANTS FOR ACIDS AT 25 ˚C Name Formula Ka1 Ka2 Ka3 Acetic HC2H3O2 1.8 x 10 –5 Ascorbic HC6H7O6 8.0 x 10 –3 Arsenic H3AsO4 5.6 x 10 –3 1.0 x 10–7 3.0 x 10–12 Arsenous H3AsO3 6.0 x 10 –10 Benzoic HC7H5O2 6.5 x 10 –5 Boric H3BO3 5.8 x 10 –10 Butyric acid HC4H7O2 1.5 x 10 –5 Carbonic H2CO3 4.3 x 10 –7 5.6 x 10–11 Cyanic HCNO 3.5 x 10–4 Citric H3C6H5O7 7.4 x 10 –4 1.7 x 10–5 4.0 x 10–7 Formic HCHO2 1.8 x 10 –4 Hydroazoic HN3 1.9 x 10 –5 Hydrocyanic HCN 4.9 x 10–10 Hydrofluoric HF 7.2 x 10–4 Hydrogen chromate ion HCrO4 – 3.0 x 10–7 Hydrogen peroxide H2O2 2.4 x 10 –12 Hydrogen selenate ion HSeO4 – 2.2 x 10–2 Hydrogen sulfate ion HSO4 – 1.2 x 10–2 Hydrogen sulfide H2S 5.7 x 10 –8 1.3 x 10–13 Hypobromous HBrO 2.0 x 10–9 Hypochlorous HClO 3.0 x 10–8 Hypoiodus HIO 2.0 x 10–11 Iodic HIO3 1.7 x 10 –1 Lactic HC3H5O3 1.4 x 10 –4 Malonic H2C3H2O4 1.5 x 10 –3 2.0 x 10–6 Oxalic H2C2O4 5.9 x 10 –2 6.4 x 10–5 Nitrous HNO2 4.5 x 10 –4 Phenol HC6H5O 1.3 x 10 –10 Phosphoric H3PO4 7.5 x 10 –3 6.2 x 10–8 4.2 x 10–13 Paraperiodic H5IO6 2.8 x 10 –2 5.3 x 10–9 Propanoic HC3H5O2 1.4 x 10 –5 Pyrophosphoric H4P2O 3.0 x 10 –2 4.4 x 10–3 Selenous H2SeO3 2.3 x 10 –3 5.3 x 10–9 Sulfuric H2SO4 strong acid 1.2 x 10 –2 Sulfurous H2SO3 1.7 x 10 –2 6.4 x 10–8 Tartaric H2C4H4O6 1.0 x 10 –3 4.6 x 10–5 E.2 DISSOCIATION CONSTANTS FOR BASES AT 25˚C Name Formula Kb Name Formula Kb Ammonia NH3 1.8 x 10 –5 Hydroxylamine HONH2 1.1 x 10 –8 Aniline C6H5NH2 4.3 x 10 –10 Methylamine CH3NH2 4.4 x 10 –4 Dimethylamine (CH3)2NH 5.4 x 10 –4 Pyridine C5H5N 1.7 x 10 –9 Ethylamine C2H5NH2 6.4 x 10 –4 Trimethylamine (CH3)3N 6.4 x 10 –5 Hydrazine H2NNH2 1.3 x 10 –6 CHEM 1515 Exam V – F93 Page 15 A. Acidic Solution Eo(V) Li+ + e– → Li(s) –3.045 K+ + e– → K(s) –2.925 Ba2+ + 2e– → Ba(s) –2.906 Sr2+ + 2e– → Sr(s) –2.888 Ca2+ + 2e– → Ca(s) –2.866 Na+ + e– → Na(s) –2.714 Mg2+ + 2e– → Mg(s) –2.363 H2(g) + 2e – → 2H– –2.25 Al3+ + 3e– → Al(s) –1.662 Mn2+ + 2e– → Mn(s) –1.185 Zn2+ + 2e– → Zn(s) –0.763 Cr3+ + 3e– → Cr(s) –0.744 Fe2+ + 2e– → Fe(s) –0.440 Cr3+ + e– → Cr2+ –0.408 Cd2+ + 2e– → Cd(s) –0.403 PbSO4(s) + 2e – → Pb(s) + SO4 2– –0.359 PbCl2(s) + 2e – → Pb(s) + 2Cl– –0.268 Ni2+ + 2e– → Ni(s) –0.250 Sn2+ + 2e– → Sn(s) –0.136 Pb2+ + 2e– → Pb(s) –0.126 2H+ + 2e– → H2(g) 0.000 S(s) + 2H+ + 2e– → H2S(aq) 0.142 Sn4+ + 2e– → Sn2+ 0.15 Sb2O3(s) + 6H + + 6e– → 2Sb(s) + 3H2O(l) 0.152 Cu2+ + e– → Cu+ 0.153 SO4 2– + 4H+ + 2e– → H2SO3(aq) + H2O(l) 0.172 AgCl(s) + e– → Ag(s) + Cl– 0.222 Cu2+ + 2e– → Cu(s) 0.337 SO4 2– + 8H+ + 6e– → S(s) + 4H2O(l) 0.357 H2SO3(aq) + 4H + + 4e– → S(s) + 3H2O(l) 0.450 I2(s) + 2e – → 2I– 0.536 MnO4 – + e– → MnO4 2– 0.564 [PtCl6] 2– + 2e– → [PtCl4] 2– + 2Cl– 0.68 O2(g) + 2H + + 2e– → H2O2(aq) 0.682 Fe3+ + e– → Fe2+ 0.771 Hg2+ + 2e– → Hg(l) 0.788 Ag+ + e– → Ag(s) 0.799 2NO3 – + 4H+ + 2e– → N2O4(g) + 2H2O(l) 0.803 2Hg2+ + 2e– → Hg2 2+ 0.920 NO3 – + 4H+ + 3e– → NO(g) + 2H2O(l) 0.96 Pd2+ + 2e– → Pd(s) 0.987 Br2(l) + 2e – → 2Br– 1.065 Br2(aq) + 2e – → 2Br– 1.087 ClO4 – + 2H+ + 2e– → ClO3 – + H2O(l) 1.19 2IO3 – + 12H+ + 10e– → I2(s) + 6H2O(l) 1.195 Pt2+ + 2e– → Pt(s) ~1.2 ClO3 – + 3H+ + 2e– → HClO2(aq) + H2O(l) 1.21 O2(g) + 4H + + 4e– → 2H2O(l) 1.229 O2(g) + 4H +(pH = 7) + 4e– → 2H2O(l) 0.83 MnO2(s) + 4H + + 2e– → Mn2+ + 2H2O(l) 1.23 2HNO2(aq) + 4H + + 4e– → N2O(g) + 3H2O(l) 1.29 Cr2O7 2– + 14H+ + 6e– → 2Cr3+ + 7H2O(l) 1.33 Cl2(g) + 2e – → 2Cl– 1.360 PbO2(s) + 4H + + 2e– → Pb2+ + 2H2O(l) 1.455 Au3+ + 3e– → Au(s) 1.498 MnO4 – + 8H+ + 5e– → Mn2+ + 4H2O(l) 1.51 2HClO(aq) + 2H+ + 2e– → Cl2(g) + 2H2O(l) 1.63 HClO2(aq) + 2H + + 2e– → HClO(aq) + H2O(l) 1.645 H2O2(aq) + 2H + + 2e– → 2H2O(l) 1.776 S2O82– + 2e– → 2SO42– 2.00 O3(g) + 2H + + 2e– → O2(g) + H2O(l) 2.07 F2(g) + 2e – → 2F– 2.87 F2(g) + 2H + + 2e– → 2HF(aq) 3.06 B. Alkaline Solution Eo(V) Mg(OH)2(s) + 2e – → Mg(s) + 2OH– –2.690 Al(OH)3(s) + 3e – → Al(s) + 3OH– –2.30 Zn(OH)2(s) + 2e – → Zn(s) + 2OH– –1.245 Fe(OH)2(s) + 2e – → Fe(s) + 2OH– –0.877 2H2O(l) + 2e – → H2(g) + 2OH – –0.828 2H2O(l) + 2e – → H2(g) + 2OH –(pH = 7) –0.43 Cd(OH)2(s) + 2e – → Cd(s) + 2OH– –0.809 Ni(OH)2(s) + 2e – → Ni(s) + 2OH– –0.72 Fe(OH)3(s) + e – → Fe(OH)2(s) + OH – –0.56 2S(s) + 2e– → S2 2- –0.447 Cu2O(s) + H2O(l) + 2e – → 2Cu(s) + 2OH– –0.358 CrO4 2– + 4H2O(l) + 3e – → Cr(OH)3(s) + 5OH – –0.13 MnO2(s) + 2H2O(l) + 2e – → Mn(OH)2(s) + 2OH – –0.05 NO3 – + H2O(l) + 2e – → NO2 – + 2OH– 0.01 HgO(s) + H2O(l) + 2e – → Hg(l) + 2OH– 0.098 PbO2(s) + H2O(l) + 2e – → PbO(s) + 2OH– 0.247 ClO3 – + H2O(l) + 2e – → ClO2 – + 2OH– 0.33 ClO4 – + H2O(l) + 2e – → ClO3 – + 2OH– 0.36 O2(g) + 2H2O(l) + 4e – → 4OH– 0.401 NiO2(s) + 2H2O(l) + 2e – → Ni(OH)2(s) + 2OH – 0.490 MnO4 – + 2H2O(l) + 3e – → MnO2(s) + 4OH – 0.588 BrO3 – + 3H2O(l) + 6e – → Br– + 6OH– 0.61 ClO– + H2O(l) + 2e – → Cl– + 2OH– 0.89 O ( ) H O(l) 2 O ( ) 2OH 1 24 CHEM 1515 Exam V – F93 Page 16 CHEM 1515 Exam V – F93 Page 17 Thermodynamic Values (25 ˚C) Substance ∆Ho f ∆G o f S o and State   kJ mol   kJ mol   J K.mol Substance ∆Ho f ∆G o f S o and State   kJ mol   kJ mol   J K.mol Carbon C(s) (graphite) 0 0 6 C(s) (diamond) 2 3 2 CO(g) -110.5 -137 198 CO2(g) -393.5 -394 214 CH4(g) ? -51 186 CH3OH(g) -201 -163 240 CH3OH(l) -239 -166 127 H2CO(g) -116 -110 219 HCOOH(g) -363 -351 249 HCN(g) 135.1 125 202 C2H2(g) 227 209 201 C2H4(g) 52 68 219 CH3CHO(g) -166 -129 250 C2H5OH(l) -278 -175 161 C2H6(g) -84.7 -32.9 229.5 C3H6(g) 20.9 62.7 266.9 C3H8(g) -104 -24 270 Bromine Br2(l) 0 0 152. BrCl(g) 14.64 -0.96 240 C h l o r i n e Cl2(g) 0 0 223 Cl2(aq) -23 7 121 Cl-(aq) -167 -131 57 HCl(g) -92 -95 187 Fluorine F2(g) 0 0 203 F-(aq) -333 -279 -14 HF(g) -271 -273 174 Hydrogen H2(g) 0 0 131 H(g)217 203 115 H+(aq) 0 0 0 OH-(aq) -230 -157 -11 H2O(l) -286 -237 70 H2O(g) -242 -229 189 Magnes ium Mg(s) 0 0 33 Mg(aq) -492 -456 -118 MgO(s) -601 -569 26.9 O x y g e n O2(g) 0 0 205 O(g)249 232 161 O3(g) 143 163 239 N i t r o g e n N2(g) 0 0 192 NCl3(g) 230 271 -137 NF3(g) -125 -83.6 -139 NH3(g) ? -17 193 NH3(aq) ? -27 111 NH2CONH2(aq) ? ? 174 NO(g) 90 87 211 NO2(g) 32 52 240 N2O(g) 82 104 220 N2O4(g) 10 98 304 N2O5(g) -42 134 178 N2H3CH3(l) 54 180 166 HNO3(aq) -207 -111 146 HNO3(l) -174 -81 156 NH4Cl(s) -314 -201 95 NH4ClO4(s) -295 -89 186 S i l v e r Ag(s) 0 0 42.6 Ag+(aq) 105.6 77.1 72.7 Ag(S2O3)3-(aq) -1285.7 -- -- AgBr(s) -100.4 -96.9 107.1 AgCl(s) -127.1 -109.8 96.2 Sulfur S(rhombic) 0 0 31.8 SO2(g) -296.8 -300.2 248.8 SO3(g) -395.7 -371.1 256.3 H2S(g) -20.17 -33.0 205.6 Titanium TiCl4(g) -763 -727 355 TiO2(s) -945 -890 50 Aluminum AlCl3(s) -526 -505 184 Barium BaCl2(aq) -872 -823 123 Ba(OH)2·8H2O(s) -3342 -2793 427 Iod ine I2(s) 0 0 116.7 HI(g) 25.94 1.30 206.3