© Keeney-Kennicutt, 2010 B 1 NAME (Block Print)______________________________________ CHEMISTRY 102 FALL 2010 FINAL EXAM FORM B 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. Which is the correct Kc expression for the equilibrium: CH4(g) →← C(s) +2H2(g)? (a) Kc = [H2]2[CH4] (b) Kc = [C][H2]2[CH4] (c) Kc = [C][2H2]2[CH4] (d) Kc = 2[H2][CH4] (e) [C]2[H2][CH4] 3&4. This sketch represents which of the following situations where : is X and is Y? (a) Y2 →← X K << 1 (b) 2X →← Y K >> 1 (c) X2 →← Y K << 1 (d) Y →← X2 K << 1 (e) Y →← 2X K >> 1 5&6. When the change in entropy of a system, ∆S is negative, then: (a) order is increasing (b) disorder is increasing (c) ∆G must be negative (d) the reaction is spontaneous (e) the reaction is non-spontaneous 7&8. Which of the following soluble ionic compounds has the largest ideal van’t Hoff factor, iideal? (a) KBr (b) NH4NO3 (c) AlCl3 (d) NaBrO (e) LiHSO4© Keeney-Kennicutt, 2010 B 2 9&10. Which choice includes ALL the following processes that are accompanied by an increase in entropy? (1) Br2(s) Æ Br2(l) (2) Mg(OH)2(s) Æ Mg2+(aq) + 2OH-(aq) (3) 2Br(g) Æ Br2(g) (4) N2(g) + 3H2(g) Æ 2NH3(g) (a) 1,2 (b) 1,3 (c) 3,4 (d) 3 (e) 2,4 11&12.The hydrolysis constant used when finding the pH of a solution of NaCN is: (a) KwKa for Na+ (b) Ka for Na+Kw (c) Ka for HCNKw (d) KwKa for HCN (e) Ka for HCNKb for CN− 13&14. A 0.10 M solution of which one of the following salts has a pH less than 7? (a) Ba(NO2)2 (b) NaF (c) KClO4 (d) CH3NH3Cl (e) KCN 15&16. From the table of thermodynamic data, we see that ΔHo f 298 (kJ/mol) for NO2(g) is +33.1 kJ/mol. This value is the ΔH for the following reaction: (a) N2(g) + 2O2(g) Æ 2NO2(g) (b) 2NO2(g) Æ N2(g) + 2O2(g) (c) 2N(g) + O2(g) Æ NO2(g) (d) NO2(g) Æ ½ N2(g) + O2(g) (e) ½ N2(g) + O2(g) Æ NO2(g) 17&18.Which of the following combinations are buffer solutions? All components are present in 0.50 M concentrations. (1) HCN and NaCN (2) NH3 and NH4Cl (3) HNO3 and NH4NO3 (4) HClO3 and NaClO3 (a) 1, 3, 4 (b) 1,2 (c) 2, 3, 4 (d) 3, 4 (e) 1, 3© Keeney-Kennicutt, 2010 B 3 19&20. Of the following species, which is the STRONGEST oxidizing agent? (a) Zn (b) Cu (c) Sn2+ (d) Ag+ (e) Co2+ 21&22. During the electrolysis of aqueous KCl solution using inert electrodes, chlorine gas 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 chlorine gas is evolved is the anode. (b) Faraday’s Law says that the longer the cell runs, the more H2(g) will be produced. (c) The electrode where the hydrogen gas is evolved is positively charged. (d) The electrons flow out of the battery into the negatively charged electrode. (e) The chloride concentration in the cell will decrease. 23&24. Which of the following salts has the lowest molar solubility? (a) BaF2 (b) CaF2 (c) MgF2 (d) SnS2 (e) PbCl2 25&26. Consider the following gas phase reaction: A + 2B → AB2 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) k[B] (c) k[A][B] (d) k[B]2 (e) k[A][B]2 27&28. For a reaction where ΔH is +255 kJ/mol rxn and ΔS = +52 J/K, _______. (a) the reaction is spontaneous at all temperatures. (b) the reaction is nonspontaneous at all temperatures (c) the reaction is spontaneous only at temperatures above a certain value. (d) the reaction is spontaneous only at temperatures below a certain value. (e) It is impossible to tell if the reaction is or is not spontaneous.© Keeney-Kennicutt, 2010 B 4 29&30. Reduction always occurs at the: (a) platinum electrode (b) positive electrode (c) negative electrode (d) cathode (e) anode 31&32. Which of the following statements is/are TRUE concerning the action of catalysts? (1) Catalysts participate in the reaction. (2) Their presence do not change the mechanism of the reaction. (3) The activation energy of the rate-determining step is raised and the reaction speeds up. (a) 1,2 (b) 1 only (c) 1,3 (d) 1,2,3 (e) none of these 33&34. Consider the gas-phase equilibrium system represented by the equation: 2 CO(g) + O2(g) →← 2CO2(g) given that the conversion of "left-hand" species (the reactants) to "right-hand" species (the products) as written, is exothermic, which of the following changes will INCREASE the equilibrium mass of CO? (a) decreasing the volume of the system at constant temperature (b) increasing the temperature (c) removing CO2 gas from the system as it is formed (d) adding a catalyst (e) adding more oxygen gas 35&36. In a 1.0 liter container there are 0.62 mole N2, 0.50 mole H2 and 0.24 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) 0.74 (b) 2.7 (c) 1.3 (d) 0.60 (e) 0.37© Keeney-Kennicutt, 2010 B 5 37&38. Consider the following reaction and standard free energy