2007 Exam

Chemistry 162 Exam III April 18, 2007 Student Name (Print): ____________________ Recitation Section Number: F F Recitation Instructor: __________________ The exam booklet has 25 questions for credit and one additional question to check the color of your exam booklet. Please answer all 26 questions on the OpScan sheet. Use the best answer of the choices available. There is no penalty for guessing. At the end of the 80-minute exam period, please hand in only this top sheet and your OpScan form. If you finish early, please do not disturb your fellow students. A proctor will check your picture ID, OpScan form, signature and calculator during the exam. The use of calculators with permanent memories (graphing calculators), cell phones, pagers, PDAs or other electronic devices other than a basic scientific calculator is expressly forbidden. The last page of the booklet contains a periodic table along with other useful data. The use of any other notes or information on this test will be considered a violation of the Academic Honesty provisions of the student code. Exam scores will be posted as soon as possible. There is a 5 point penalty for incorrectly filling out the OpScan form. ON THE OpScan FORM (Use a #2 pencil or darker) Sec Per. Instr Sec Per. Instr 1. SIGN your name across the top of the form. 01 M3 RA 30 Th3 NM 2. Code the following information (blacken circles) 03 M5 RA 31 Th3 ET Your Name (LAST NAME FIRST) 04 M5 MR 33 M6 RA Your RU ID NUMBER 06 W3 DS 34 M6 NM [Start under Box A and continue to Box I] 07 W3 LP 36 W6 HS Your RECITATION SECTION NUMBER in K & L 08 W5 LP 37 M8 NM [Sections 01-08, code a 0 under box K] 0S TBA AM (Please code 99) 39 W8 HS Your EXAM FORM NUMBER under box P 11 F3 HS 17 M1 MR LP = L. Petrone, RA = R. Agarwal, AM = A. McGhan 19 M3 NM HS = H. Sangari, DS = D. Siegel, NM = N. Marky 20 M3 DS MR = M. Rabeony, ET = E. Tavss 23 W1 ET Periods: 1 = 9:30-10:25, 3 = 12:15-1:10 or 12:50-1:45 25 W3 ET 5 = 3:35-4:30, 6 = 5:15-6:10, 8 = 8:25p-9:20p 26 W3 NM Your EXAM FORM is c C162s07e3v1 Your EXAM FORM is c 1 Given the following data. H 2 (g) + O 2 (g) ? H 2 O 2 K = 2.3 × 10 6 2 H 2 (g) + O 2 (g) ? 2 H 2 O(g) K = 1.8 × 10 37 Calculate ?G o at 600 K for the reaction H 2 O(g) + ½ O 2 (g) ? H 2 O 2 (g) : A. 140 kJ B. -220 kJ C. -290 kJ D. -350 kJ E. +290 kJ 2 The following reaction is exothermic. 2CuO(s) + C(s) ? 2Cu(s) + CO 2 (g) Which one of the following statements is correct at standard conditions? A. The reaction will only be spontaneous at very high temperatures. B. It is impossible to determine whether the reaction is spontaneous without calculation. C. The reaction is spontaneous at all temperatures D. The reaction is not spontaneous at any temperature E. The reaction will only be spontaneous at low temperatures 3 Consider the following two half reactions and the statements that follow: Ag + (aq) + 1e - ? Ag(s) 2Ag + (aq) + 2e - ? 2Ag(s) X. ?Gº is the same for both reactions Y. ?º is the same for both reactions Z. Both reactions are oxidations Which of the above statements is (are) correct? A. X only B. X and Y only C. Y and Z only D. Y only E. Z only C162s07e3v1 4 When the following half reaction (shown unbalanced) occurs in acidic medium, the number of moles of electrons transferred per mole of Br 2 is Br 2 ? BrO 3 - (aq) A. 1 B. 2 C. 5 D. 8 E. 10 5 What is the solubility of AgI(s) in a solution that is 2.0 M NH 3 ? [Ag(NH 3 ) 2 ] + K f = 1.7 × 10 7 AgI(s) K sp = 1.5 × 10 -16 A. 1.0 × 10 -4 mol/L B. 1.5 × 10 -3 mol/L C. 5.6 × 10 -6 mol/L D. 8.4 × 10 -5 mol/L E. 6.6 × 10 -9 mol/L 6 What is the coordination number of Co in [CoCl 2 (en)(NH 3 ) 2 ]Cl? ("en" is H 2 NCH 2 CH 2 NH 2 ) A. 3 B. 4 C. 5 D. 6 E. 7 C162s07e3v1 7 Consider the freezing of liquid water at ?10 o C. What are the signs of ?H, ?S, and ?G for this process? ?H ?S ?G A + - 0 B - + 0 C - + - D + - - E - - - 8 The numbers of geometric isomers and optical isomers of the complex ion [Co(en) 3 ] 3+ (en = ethylenediamine = H 2 NCH 2 CH 2 NH 2 ) are, respectively: A. 2 and 2 B. 1 and 1 C. 3 and 2 D. 1 and 2 E. 3 and 3 9 Consider the following statements X. All geometric isomers are also structural isomers Y. A pair of enantiomers are nonsuperimposable mirror images Z. Compounds that display optical isomerism are structural isomers Which ones are true statements? A. X only B. Y and Z C. Y only D. X and Z E. Z only C162s07e3v1 10 Calculate the equilibrium constant at 25 o C for the following reaction: N 2 O 4 (g) ? 2NO 2 (g) ?G f o (kJ/mol) 97.8 51.3 A. 4.5 B. 0.14 C. 1.8 D. 4.0 × 10 -2 E. 2.6 × 10 28 11 For the decomposition of MgCO 3 (s): MgCO 3 (s) ? MgO(s) + CO 2 (g) ?H o = 100.59 kJ and ?S o =174.98 J K -1 . Under standard conditions, A. the reaction is spontaneous at temperatures greater than 575 K B. the reaction is spontaneous at temperatures less than 575 K C. the reaction is not spontaneous at any temperature D. the reaction is spontaneous only at 575 K E. the reaction is spontaneous at all temperatures 12 The compounds or ions listed below are either square-planar or octahedral. Which one does not form cis-trans isomers: A. [FeCl 3 (NH 3 ) 3 ] - B. [CuCl(NH 3 ) 3 ] + C. [CoCl 4 (NH 3 ) 2 ] + D. [CoCl 2 (NH 3 ) 4 ] + E. [PtCl 2 (NH 3 ) 2 ] C162s07e3v1 13 Given: Br 2 (l) + 2e - ? 2Br - (aq) ? o = -1.07 V I 2 (s) + 2e - ? 2I - (aq) ? o = 0.53 V Calculate the equilibrium constant at 25 ºC for the reaction 2Br - (aq) + I 2 (s) ? Br 2 (l) + 2I - (aq) A. 1.1×10 27 B. 1.2×10 54 C. 3.0×10 -37 D. 5.5×10 -19 E. 7.4×10 -10 14 Given: NiCO 3 (s) + 6 NH 3 (aq) ? [Ni(NH 3 ) 6 ] 2+ (aq) + CO 3 2- (aq) K c = 3.0 NiCO 3 (s) K sp = 6×10 -9 Calculate K f for the reaction Ni 2+ (aq) + 6 NH 3 (aq) ? [Ni(NH 3 ) 6 ] 2+ (aq) K f = ?? A. 2×10 -8 B. 5×10 8 C. 2×10 -9 D. 3.0 E. 6×10 -9 15 The coefficients (?a? and ?b?) needed to balance the following equation are Cr 2 O 7 2- (aq) + a Br - (aq) + H + (aq) ? Cr 3+ (aq) + b H 2 O + Br 2 (l) A. a = 8, b = 4 B. a = 6, b = 7 C. a = 4, b = 8 D. a = 1, b = 1 E. a = 2, b = 7 C162s07e3v1 16 Determine ? o for a voltaic cell that utilizes the following reaction: 2Al 3+ (aq) + 3Mg(s) ? 2Ag(s) + 3Mg 2+ (aq) Given Al 3+ + 3e - ? Al(s) ? o = -1.66 V Mg 2+ +2e - ? Mg(s) ? o = -2.37 V A. 0.35 V B. 0.71 V C. 0.86 V D. 1.31 V E. 1.71 V 17 Which compound or ion has an incorrect formula? A. Hexacarbonyltungsten [W(CO) 6 ] B. Hexafluorocobaltate(III) [CoF 6 ] 3- C. Tetrachloroplatinate(II) [PtCl 4 ] 2- D. Tetraamminebromochlorochromium(III) [CrBrCl(NH 3 ) 4 ] 2+ E. Hexacyanoferrate(III) [Fe(CN) 6 ] 3- 18 What is the overall reaction for the following cell diagram? Al(s) ?Al 3+ (aq) ?? H + (aq) ?H 2 (g) ? Pt(s) A. H 2 (g) + Al 3+ (aq) ? 6H + + 2Al(s) B. Al 3+ (aq) + 6H + (aq) ? 3H 2 (g) + 2Al(s) C. Al(s) + 3H + (g) + Pt(s)? Al 3+ (aq) + PtH 3 (s) D. H 2 (aq) + Al 3+ (aq) + Pt(s) ?Al(s) + PtH 4 (s) E. 2Al(s) + 6H + (aq) ? 2Al 3+ (aq) + 3H 2 (g) C162s07e3v1 19 A system undergoes a change of state during which 64.0 kJ of heat is transferred to the surroundings at a constant pressure of 1 atm and a constant temperature of 300 K. For this process ?S surr is: A. 64.0 kJ B. -64.0 kJ C. -213 J/K D. 213 J/K E. 300 J/K 20 For a spontaneous reaction, the Second Law of Thermodynamics requires: A. ?S univ >0 B. ?S sys > 0 C. ?H sys > 0 D. ?H sys < 0 E. ?H surr > 0 21 Which of the following is true for the cell shown below? Zn(s) | Zn 2+ (aq) || Cr 3+ (aq) | Cr(s) A. Electrons flow from the cathode to the anode B. Electrons flow from the zinc to the chromium C. Electrons flow from the chromium to the zinc D. Chromium is oxidized E. Zinc is reduced C162s07e3v1 22 Which of the following pairs of complexes are structural isomers? A. [Co(H 2 O) 4 ] 2+ and [Co(H 2 O) 6 ] 2+ B. [Co(NH 3 ) 4 ] 2+ and [Co(NH 3 ) 3 (H 2 O)] 2+ C. [Co(NH 3 ) 3 (SCN)] 2+ and [Co(NH 3 ) 3 (NCS)] 2+ D. [Co(NH 3 ) 3 (N 2 O)] 2+ and [Rh(NH 3 ) 3 (N 2 O)] 2+ E. [cis-Co(NH 3 ) 2 (N 2 O) 2 ] 2+ and [trans-Co(NH 3 ) 2 (N 2 O) 2 ] 2+ 23 Zn(OH) 2 is amphoteric. In which one of the following solutions would the solubility of Zn(OH) 2 be lowest A. pure water B. 1 M NaOH C. 1 M ZnCl 2 D. 1 M HCl E. 1 M NH 3 24 For the reaction 2C(graphite) + H 2 (g) ? C 2 H 2 (g) ?G o = 209.2 kJ at 25 o C. Calculate ?G at 25 o C for the reaction when P(H 2 ) = 100 atm and P(C 2 H 2 ) = 0.10 atm. A. 207.8 kJ B. 226.3 kJ C. 192.1 kJ D. 17.3 kJ E. -16.9 kJ C162s07e3v1 25 Consider the following statements regarding the process H 2 O(l) ? H 2 O(g) X. ?S sys is positive at 1.0 atm and temperatures above 100 o C Y. ?S surr is negative at 1.0 atm and temperatures above 100 o C Z. ?S univ is positive at 1.0 atm and temperatures above 100 o C Which ones are true? A. X only B. Y only C. X and Y only D. X and Z only E. X, Y, and Z 26 What color is your exam? A. white B. yellow C. blue D. pink C162s07e3v1 Your EXAM FORM is c Constants and Formulae 1 L atm = 101.325 J 1 atm = 760 Torr = 101.325kPa N A = 6.022×10 23 mol -1 R = 0.08206 L atm mol -1 K -1 = 8.3145 J mol -1 K -1 F = 9.6485 x 10 4 C/mol ?G = ?H ? T?S ?? °?°=°? ReactantsProducts nSnSS ?? °??°?=°? Reactants f Products f GnGnG ?G = ?G° + RTlnQ ?G = -nF? ?° cell =?° cathode - ?° anode ? cell = ?° cell ? n V02569.0 ln Q = ?° cell - n V0592.0 log Q ?S surr = T H T q rev ?? = ?° cell = n V02569.0 ln K = n V0592.0 log K ? ? ? ? ? ? ? ? ? °? = ? ? ? ? ? ? ? ? 122 1 11 ln TTR H K K C162s07e3v1 Donald Siegel 1