© Keeney-Kennicutt, 2010 A 1 NAME (Block Print)______________________________________ CHEMISTRY 102 FALL 2010 FINAL EXAM FORM A Section 501 DR. KEENEY-KENNICUTT Directions: (1) Put your name on PART 1 and your name and signature on PART 2 of the exam where indicated. (2) Sign the Aggie Code on PART 2 of this exam. (3) Each multiple choice question is actually 2 questions on your scanning sheet. If you are sure of an answer, put the same answer down for both questions for 5 pts. If you cannot decide between two answers, put your best answer down for the first (odd) question and the other answer down for the second (even) question. If you get the first one correct you'll get 3 pts; if you get the second one correct you’ll get 2 pts. If there is an ambiguous multiple choice question, use the last page to explain your answer. (4) Do NOT write on the envelope. (5) When finished, put everything in the envelope and wait to be excused. At the table, take everything out of the envelope. You can pick up the multiple choice part with the answers outside my office after 10:30 am on Wednesday. (6) There are a total of 60 multiple choice questions (30 actual questions) plus 20 pts free response. PART 1 1&2. When the change in entropy of a system, ∆S is positive, then: (a) the reaction is spontaneous (b) the reaction is non-spontaneous (c) ∆G must be negative (d) disorder is increasing (e) order is increasing 3&4. Of the following species, which is the STRONGEST reducing agent? (a) Mg (b) Sn4+ (c) Ag+ (d) Cu (e) Co2+ 5&6. Which of the following combinations are buffer solutions? All components are present in 0.10 M concentrations. (1) NH3 and NH4Cl (2) HNO3 and NH4NO3 (3) HCN and NaCN (4) HClO3 and NaClO3 (a) 1, 3, 4 (b) 1, 2 (c) 2, 3, 4 (d) 3, 4 (e) 1, 3 7&8. A 0.10 M solution of which one of the following salts has a pH greater than 7? (a) CH3NH3Cl (b) NaBrO (c) Ca(NO3)2 (d) KBr (e) NH4Cl© Keeney-Kennicutt, 2010 A 2 9&10. This sketch represents which of the following situations where : is A and is B. (a) 2A →← B K >> 1 (b) B2 →← A K << 1 (c) B →← A2 K >> 1 (d) A2 →← B K << 1 (e) A →← B2 K << 1 11&12. From the table of thermodynamic data, we see that ΔHo f 298 (kJ/mol) for MgO(s) is –601 kJ/mol. This value is the ΔH for the following reaction: (a) Mg(s) + O(g) Æ MgO(s) (b) MgO(s) Æ Mg(s) + ½ O2(g) (c) 2MgO(s) Æ Mg(s) + O2(g) (d) Mg(s) + ½ O2(g) Æ MgO(s) (e) 2Mg(s) + O2(g) Æ 2MgO(s) 13&14. Oxidation always occurs at the: (a) platinum electrode (b) positive electrode (c) negative electrode (d) cathode (e) anode 15&16. Consider the gas phase reaction: 2C + D → C2D that occurs by the following mechanism: Step 1 C + C → C2 slow Step 2 C2 + D → C2D fast Overall 2C + D → C2D The rate law expression must be Rate = ________. (a) k[D] (b) k[C]2[D] (c) k[C][D] (d) k[C]2 (e) k[C]© Keeney-Kennicutt, 2010 A 3 17&18. Which is the correct Kc expression for the equilibrium: N2H4(l) →← N2(g) + 2H2(g)? (a) Kc = [N2]⋅2[H2][N2H4] (b) Kc = [N2][2H2]2[N2H4] (c) Kc = [N2][H2]2[N2H4] (d) Kc = [N2][2H2]2 (e) Kc = [N2][H2]2 19&20. Consider the gas-phase equilibrium system represented by the equation: NO2(g) + O2(g) →← NO(g) + O3(g) given that the conversion of "left-hand" species (the reactants) to "right-hand" species (the products) as written, is endothermic, which of the following changes will DECREASE the equilibrium amount of NO? (a) lower the temperature (b) decreasing the volume of the container at constant temperature (c) removing more ozone (d) adding more oxygen gas (e) adding a catalyst 21&22. Which of the following soluble ionic compounds has the largest ideal van’t Hoff factor, iideal? (a) AlCl3 (b) LiHSO4 (c) NH4NO3 (d) NaCN (e) KCl 23&24.The hydrolysis constant used when finding the pH of a solution of NaCN is: (a) Ka for HCNKb for CN− (b) Ka for HCNKw (c) KwKa for HCN (d) Ka for Na+Kw (e) KwKa for Na+ 25&26. Which choice includes ALL the following processes that are accompanied by an increase in entropy? (1) I2(s) Æ I2(g) (2) 2I(g) Æ I2(g) (3) 2NH3(g) Æ N2(g) + 3H2(g) (4) Mg2+(aq) + 2OH-(aq) Æ Mg(OH)2(s) (a) 1,2 (b) 1,3 (c) 3,4 (d) 3 (e) 2,4© Keeney-Kennicutt, 2010 A 4 27&28. For a voltaic cell using Ag+(1 M)/Ag and Cu2+(1 M)/Cu half cells, which of the following statements is incorrect? (a) The copper electrode is the anode. (b) Electrons will flow through the external circuit from the copper electrode to the silver electrode. (c) Reduction occurs at the silver electrode as the cell operates. (d) The mass of the copper electrode will decrease as the cell operates. (e) The concentration of Ag+ will increase as the cell operates. 29&30. For a reaction where ΔH is –345 kJ/mol rxn and ΔS = –48 J/K, _______. (a) the reaction is spontaneous only at temperatures above a certain value. (b) the reaction is spontaneous only at temperatures below a certain value. (c) the reaction is spontaneous at all temperatures. (d) the reaction is nonspontaneous at all temperatures (e) It is impossible to tell if the reaction is or is not spontaneous. 31&32. Which of the following statements is/are TRUE concerning the action of catalysts? (1) Their presence always changes the mechanism of the reaction. (2) Catalysts do not participate in the reaction. (3) The activation energy of the rate-determining step is lowered and the reaction speeds up. (a) 1, 3 only (b) 2, 3 only (c) 2 only (d) 1, 2, 3 (e) 1, 2 only 33&34. Which of the following salts has the highest molar solubility? (a) BaF2 (b) CaF2 (c) MgF2 (d) SnS2 (e) PbCl2© Keeney-Kennicutt, 2010 A 5 35&36. What is the pH of a 1.9 x 10-5 M HCl? (a) 2.35 (b) 4.51 (c) 4.72 (d) 3.09 (e) 3.17 37&38. In a 1.0 liter container there are 0.20 mole N2, 0.10 mole H2 and 0.40 mole NH3 in the system at equilibrium. N2(g) + 3 H2(g) →← 2 NH3(g) What is the value of Kc for this reaction? (a) 0.0012 (b) 20. (c) 0.050 (d) 8.0 x 102 (e) 8.0 39&40. Rate data were collected for the following reaction at a particular temperature. What is rate law expression? A(g) + 2B(g) → C(g) + 2D(g)