© Keeney-Kennicutt, 2010 D 1 NAME (Block Print)______________________________________ CHEMISTRY 102 FALL 2010 FINAL EXAM FORM D Section 502 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 the exam. (6) There are a total of 60 multiple choice questions (30 actual questions) plus 20 pts free response. PART 1 1&2. Which one of the following combinations cannot produce a buffer solution? (a) HNO2 and NaNO2 (b) NH3 and (NH4)2SO4 (c) HClO4 and NaClO4 (d) NH3 and NH4Br (e) HCN and NaCN 3&4. The rate law for the chemical reaction, 2ClO2(aq) + 2OH−(aq) → ClO3− (aq) + ClO2−(aq) + H2O(l) has been determined experimentally to be: Rate = k[ClO2]2[OH−] The reaction order with respect to the hydroxide ions is: (a) 3 (b) 2 (c) 1 (d) k[OH−]2 (e) k[ClO2]2[OH−] 5&6. Which is the correct Kc expression for the equilibrium: 2C(s) + O2(g) →← 2CO(g) ? (a) Kc = 2[CO]2[C][O2] (b) Kc = [C]2[O2][CO]2 (c) Kc = [CO]2[C]2[O2] (d) Kc = [CO]2[O2] (e) Kc = [O2][CO]2 7&8. Which of the following statements is FALSE? (a) ΔS is a state function. (b) A reaction is spontaneous if ΔSuniverse decreases. (c) Endothermic processes are those that absorb heat. (d) At absolute 0 K, the entropy of a pure perfect crystalline substance is zero. (e) The system's enthalpy alone does not determine the spontaneity of a reaction.© Keeney-Kennicutt, 2010 D 2 9&10. The best representation for the reaction whose heat of reaction is equal to the standard molar enthalpy of formation for HNO3(g) is: (a) H(g) + N(g) + 3O(g) Æ HNO3(g) (b) HNO3(g) Æ ½ H2(g) + ½ N2(g) + 3/2 O2(g) (c) 2HNO3(g) Æ H2(g) + N2(g) + 3 O2(g) (d) H2(g) + N2(g) + 3 O2(g) Æ 2HNO3(g) (e) ½ H2(g) + ½ N2(g) + 3/2 O2(g) Æ HNO3(g) 11&12. Which statement is TRUE about aqueous solutions? (a) As the value of the van’t Hoff factor of the solute increases, the freezing point of the solution will increase. (b) A solution can only be made by dissolving a solid into a liquid. (c) When the molality of the solute doubles, the boiling point of the solution will double. (d) When a solute dissolves into the solvent, the vapor pressure of the solution will be lower than the vapor pressure of the pure solvent at a particular temperature. (e) A solution is a heterogeneous mixture in which no settling occurs. 13&14. Which of the following species is the STRONGEST oxidizing agent? (a) Co2+ (b) Zn2+ (c) Cr2+ (d) Cu (e) Cr 15&16. Consider the following gaseous phase system at equilibrium: I2(g) + Cl2(g) →← 2ICl(g) ΔH = –27 kJ Which of the following changes will DECREASE the amount of ICl at equilibrium? (a) adding N2 (g) (b) adding a catalyst (c) decreasing the volume of the container (d) adding I2 (g) (e) raising the temperature 17&18. Consider the following gas phase reaction: A + 2B → AB2, which occurs by the following mechanism: Step 1 A + B → AB slow Step 2 AB + B → AB2 fast Overall A + 2B → AB2 The rate law expression must be Rate = ________. (a) k[A][B] (b) k[B] (c) k[A][B]2 (d) k[B]2 (e) k[A]© Keeney-Kennicutt, 2010 D 3 19&20. The relationship between Ksp and s, the molar solubility in mol/L, for PbI2 is: (a) Ksp = 4s2 (b) Ksp = 4s3 (c) Ksp = s1/3 (d) Ksp = s2 (e) Ksp = s3 21&22. Consider the following reaction and choose the correct statement: H2(g) + Br2(l) → 2 HBr(g) ΔHo = –72.8 kJ ΔSo = +114 J/K (a) The reaction becomes spontaneous as the temperature increases. (b) The reaction becomes nonspontaneous as the temperature increases. (c) The reaction is nonspontaneous at all temperatures. (d) The reaction is spontaneous at all temperatures. (e) The temperature does not influence the spontaneity of any reaction. 23&24. Which of the following statements is FALSE about solubility and miscibility? (a) Iodine, I2(s), should be more soluble in water than in carbon tetrachloride, CCl4, (b) Benzene, C6H6, is miscible in chloroform, CHCl3. (c) In the phrase “Like dissolves like,” the term “like” refers to molecules with similar polarities. (d) Water and ethanol, CH3CH2OH are miscible. (e) KCl is more soluble in water than BaS. 25&26. Which one of the following statements is TRUE about the following reaction? CH3NH2 + H2O →← CH3NH3+ + OH− (a) OH− is the conjugate acid of H2O. (b) H2O is the conjugate base of OH−. (c) CH3NH2 is the conjugate base of H2O. (d) CH3NH3+ is the conjugate acid of CH3NH2. (e) There are no conjugate acid-base pairs. 27&28. Which statement or statements is/are TRUE about the purpose of a catalyst? (1) Catalysts increase the number of collisions between the reactants in the overall reaction. (2) A catalyst cannot appear as a reactant in a rate law expression. (3) A catalyst lowers the activation energy of both the forward and reverse reaction. (a) 1 & 2 (b) 2 & 3 (c) 1 & 3 (d) only 1 (e) only 3© Keeney-Kennicutt, 2010 D 4 29&30. During the electrolysis of aqueous KBr solution using inert electrodes, bromine liquid is evolved at one electrode and hydrogen gas is evolved at the other electrode. The solution around the electrode at which hydrogen gas is evolved becomes basic as the electrolysis proceeds. Which of the following is FALSE? (a) The electrode where the hydrogen gas is evolved is positively charged. (b) Faraday’s Law says that the longer the cell runs, the more H2(g)