105bf07_sample_final

105bf07_sample_final - . - “smite HM 1009 iChemistry...

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Unformatted text preview: . - “smite HM 1009 iChemistry lOSbL First Letter of PLEASE PRINT YOUR NAME IN BLOCK LETTERS 10:00 am. Section Last Name Spring 2005 Name: FINAL EXAM May 4, 2005 Last 4 Digits SID #: _ __ _ _ Professor Arieh Warshel - Lab T.A.'s Name: Lab Day and Time: Please Sign Below: I certify that I have observed all the rules of Academic Integrity while taking this examination. INSTRUCTIONS: 1. There are 10 problems on 14 pages in this exam. Please check to see that you have a complete exam. 2. Please show all of your work to receive full credit. 3. You must use ink. Do not use a pencil. 4. Letter grades will be available on OASIS only. Check OASIS after May 20, 2005. (They will not be posted.) 5. The final course scores will be posted on the class website by 12 noon, May 5, 2005. 6. Final exams may be viewed 10 am-12 noon, 2-4 pm on Mon, May 9; Tues, May 10', Wed, May 11 only. Sign-up for a 10 minute exam viewing on the sheet outside of SGM 220. #3342:- Useful Physical Constants and Equations: Avogadro's number N = 6.022 x 1023 mol“ Universal gas constant R = 0.08206 L atm K" mol‘I = 8.314 I K" mol" Faraday‘s constant F = 96,485 C mol“ R Kp=Kc(RY)A" [(3.2]? 1nk=—%° l) + lnA Ifax1+bx+c=0thenx=fizéfE PV = nRT -w = q§ l amu = 9.35 x 10' eV/molecule AS=k 111 W c=3.00x10‘m/s AG = -nF g 1 g = 6.02x10” amu AG = AG" + RT an for first order reactions, AG =AH —TAS M=Moe"“,tm=°'—i93 E=q+w €=§°—"—,}an AG" = —RT aneq :3 = a0 — 0“$3210ng keq = e—AGo/RT £0 = 0.039210810K‘q E = bl) = mc2 AG(lc/) = —96.5n§ (volt) -AIQ = _% + AS K“? = longotonssz = [H*1(Cs+[H*D (Ca-[H’D Half Reactions §° volts Cu"2 + 2e' -) Cu(s) 0.34" Zn+2 + 2e“ -) Zn(s) -0.76 Ni“z + 2e‘ -) Ni(s) -0.28 M *2 + 2e‘ -) Mg(s) -1.03 Cd+2 + 2e- —9 Cd(s) -o.4o Mno: + 8H' + 5e'-) Mn2*+4H20 1.51 Ag“ + e‘ —-) Ag(s) 0.80 C1z + 2e'-) 20- 1.36 1:2 + 2e- —+ 2? 2.87 Na+ + e‘ —-) Na(s) -2.71 Pb+2 + 2e‘-) Pb(s) -0.l3 Fe3+ + 3e' -_-) Fe -0.04 I VIII H IIIIVVVIVIIHE 6. m . 6 I 9 10 9mm 1211111 1519990 mm 179 11 12 13 16 1.5 17 1] g 22.90?) m - -- 25.!!! mu 30.9737 m 39.90 19 29 21 13 24 3 26 27 28 3 30 32 33 3 36 39.0933 M 44.9559 50.911 51.996 51.930 55.347 55.933: 53.0! 63.5“ 65.37] 7159 71.9216 79.”! an 37 39 41 42 43 45 46 ‘7 52 5 35.40 33.91159 92.9064 95.94 $9062 107.905 106.4 10716! 127.50 126.901 55 57 73 74 75 76 73 79 II 81 £2 ' I: s 137.905 138.93 150.948 19.85 186.1 190.2 195.09 196.9“ M 201.38 2w.“ mm m o w u a r I» a) 225.025 227.027 5‘ 59 63 65 66 67 GI 69 70 71 lag-aagflgagnaaaaaa 140.12 140.” 151.” 15:32: 162.50 164.” 167.26 168.!“ 173.01 174.97 90 91 72 93 95 96 N 99 100 1B lfifllflflflfiggaflgaaman moss 231.035 38.029 27.048 LI! («.1 " LA LII (.59 E") 1. (20 points) (a) (b) For the reaction 2N0 (g) + Br2 (g) —-) 2NOBr (g) the rate law is _ A[Brg] At =k[NO]2[Br2]. What will be the change in the initial rate of consumption of Br2 if the initial amount of NO is tripled? '2. pATL :. 2. (BIN Chi ENolz .— C1 For a reaction in which A and B react to form C, the following initial rate data were obtained: [A] jmoVL1 0.2 0.4 0.8 0.2 0.2 [B] (moVL) 0.2 0.2 0.2 0.4 0.8 Find the rate law for this reaction. ( Initial Rate of Formation of C moVL s 0.50 2.00 8.00 1.00 2.00 QATE= K L01“ LET/M n 2.00 p o‘ro - a7.— I.00 __ .q m 099 - Ti M CD‘S l 2. (20 points) voltmeter Consider the following cell: The standard potential for Pb2+ and Ni2+ are -0.13 V and -0.28 V, respectively. (a) What is the value ofE° for this cell at 25°C? Write the balance equation for the overall reaction. 2 - 2+ 4. I . E=—-‘O.l1+-O.28 7- o.lS’\/ (b) Which substance will be oxidized? V; N ( s) (c) What will be the potential of the above cell when the concentration obe2+ is 1.0 M and that ot‘Ni2+ is LU‘M? lo'g CD KT- jA/\ CAL-f») ,— := E we W1 ,J O M _ (gym 3’,...(K\(Z°’3 L) 1M (d) What will be the potential ofthe cell ifthe temperature IS dropped to zero? [13mm 3": [.5 (5%:in A o E:E°—T(AQ>=E E = otlgv 3. (20 points) Solution of [Co(NH,)6]”' are yellow in color, which means they absorb in the violet region of the spectrum. On the other hand, solutions of trans [Co(NH3)4C]z]* are green since they absorb in the red region of the spectrum. (a) Please explain this result in terms of the crystal field splitting energy Ao. \)\%\QLL SWQ’FW Rgfl 51‘ \l mmu anC-a ENWQV ..,_.> C WE A0 Pom CCQOMQJ“ IS Gfiumm Ac [$01.01 €02.14. E90u3i AD lg 8cm Tu "W? QJMU 0 r“ claw? Nagoch "J. u l u AND Ulocfi’f" Pl-l'cfios M chuea w 6mm M RU) Mva g (b) Consider the two octahedral complexes [Co(Cl)6]" and [Co(CN)6]" where the crystal field splitting energy A0 is 0.5 kcal/mol for the Cl‘ complex and 6 kcal/mol fo @ CN‘) +k< complex. The electron pairing energy, P, is 2 kcal/mol for both complexes. etermine which of the complexes is in the high-spin and which is in the low-spin configuration. (Hint: Co“ is d7.) gr: "l~ 4— \ p _1_,_. #347 4L _+ Hts-15ml 4+ 4H :1]? WNW“) 6C5. cf: Z(O.§)’+Z(z—)=SK¢V( Cése CI = 05* ECLV 45K“ Ccse Cn’: z ((9)4. 1(2): léKJ CFsE co‘ = (o-0 l" 2(2—3 = “Km CFge c2" Hm 89¢ A CF39; c1" Law um .‘. Cafe“?th 13 HIGH £P'xl CcSE 04' Hucu SV'A > CFSQ (N’ LU,” gFmJ .. CN- (“Pew l & Low U3. 4 (c) What will be the magnetic properties of [Co(CN)6]3' (paramagnetic or diamagnetic) P a, assuming A0 and @ are the same as in [Co(CN)6]‘? 3+ ‘9 Q Co la .4 ..— .— u‘. WlAW‘AWT‘C Loos SPU‘l ill: 4+: 4L- No WPAIQCJ; EL‘CPWMS Cfisa mo: 39.; > ops; LCM. w“) 2(a) 4' 2 3(2.) H [<91 (a Kai 4. (20 points) (a) The reaction shown below is reSponsible for creating I‘C in the atm05phere. What is the bombarding particle? l4N +I¢'__ -> 24C + 1H (i) neutron (ii) 3He or alpha (iii) _‘,’e or beta (iv) positron (b) Which statement is true about the following reaction? (.1 17110.3! 18.00g 3,4N + §He -> $70 + {H 13.992 4.0015 16.9986 1.0073 amu amu amu amu 1 @ Energy is absorbed in the reaction (ii) Energy is released in the reaction (iii) No energy change is associated with the reaction (iv) Not enough information is given to determine the energy change (c) Attempts to find the guilty party in the famous gunfight at the OK Corral (Tombstone, Arizone) lead to a detection of a skeleton whose l‘C count was about 14.01 cpm/g (the atmosphere activity of I‘C is 15.3 cpm/ g). Could it be that we finally vindicated "Doc" Holliday (played by Val Kilmer in the movie)? Explain your answer with the proper calculation "mi \AALF—LiFi <.~F '2; is §730V€AQQ' .1 ANS: =-KT=(‘9_'£°1})+ ‘lT/z A(£%KZB=C—omz )1‘, gfl‘So 7m; 1': W233 flax/Ls Fm“ QNF'WT Q MM Cam—room Pasta N I881 % "DH; SQL‘Cl—mq h”: 1331‘ flegup,’ Film 71!; ACM$ 64F Do; Lac WDAVV 4L" . 5. (20 points) A liter of water solution contains 0.02 mole per liter Ba(NO,)2 and 0.02 mole per liter Ca(N03)2, both of which are soluble salts. The following solubility product constants are given: 5 Llilbgq 1(5):: “it? LF' R5?(C0F2) .: ‘lD H ((9; CM"). U342- (a) Determine which of the two salts will precipitate first when adding NaF to the solution. |,2.¥IO - V2. \aF \L pflga'p'T—r“: “MN F- = < )3 ?.l\“ L C A OIOLM 0,0'78M a. - - ZQXIo'” Ill -5 Cali wm— F49C'P'm\c WW") [F] - ( oozm) = Ll-LHUD H OAFL VJng F‘ng , H) (b) Calculate the solubility of Ban in pure water. Il 6. (20 points) (a) The crystal field diagram of: :(CN);4 looks like: xi'ji 2; (D Q Cit—Mr"c Co — L.l i‘. 5} 0 CN X3 x2 32 Please draw the corresponding diagram for Fe(CN)§3 where one ligand is removed from the z axis (i.e., draw the crystal field diagram). .flw x232 m 2 V, 2. \ Lg m "‘3 1 it (b) Which one of the following explanations can exhibit geometrical isomerism? (i) Zn(NH3):Cl2 (tetrahedral) {J 3 (ii) [CUU‘H'IJL]2+ (square planar) M {3 (iii) Pt(NH3):Clz (square planar) ( (iv) [Co(N'l-13)5Cl]2+ (octahedral) 3g 3 (c) Name the following two complex: [Co(NH,)5Cl]Cl: W (60mm \ Ja- \" o m l: all M i) L 3m“ mammaz '3 7. (20 points) Please circle the correct answer. (i) (ii) (iii) (iv) C Choose the CORRECT statement. W ‘3'“! a) Exothermic r ons are always spontaneous. A. K b) Free e 15 independent of temperature. AL " ’5‘“ ‘ ' A r A reaction which exhibits a negative value of AS cannot be spontaneous. At constant P and T, a decrease in free energy insures an increase in the entropy of the system. e) None of the above statements is true. Consider the freezing of liquid water at -10°C. For this process what are the signs of AH, AS, and AG? Hzch -—‘9 uLo (6.) + M AH AS AG ( l A. H 4 (L a) + - 0 A '3 L (A b) - + 0 ' , c) - + - A (3 Q dI + - - When a stable diatomic molecule is formed from its atoms, what are the sign of AH°, AS°, and AG°? A 4 A 4'! A L AH" AS° AG° AH 40 a) + + + 5 < 4) b) + - - , c) - + + [3‘40 4 of) d) - - + The third law of thermodynamics states: a) The entropy of the universe is increasing. b) The entropy of the universe is constant. (:ci 3 The entropy is zero at zero K for a perfect crystal. d) The absolute entropy of a substance decreases with increasing temperature. e) The entropy of the universe equals the sum of the entropy of system and surroundings. 10 a‘ 1"“ L v . (a) (b) (C) (d) (e) (f) (g) (h) (i) (i) (20 points) Circle "True" or "False" for each of the following statements. Cl2 is a strong reducing agent. A catalyst increases the activation barrier of a reaction. According to BrOnsted and Lowry an acid is a lone pair donor. A mixture of HCl and KC] forms a good bufi‘er. EDTA bonds metal strongly because of entropic effects. dz: 15 less stable than dxy m square planar complexes. The first name of Faraday was Walter. Geometrical isomers cannot rotate polarized light. The difference in elevation between Los Angeles and Boulder is a state function. It is always true that an indicator is most effective when the pH of the equivalent point is equal to the pK. of the indicator. 11 True True True True /\ .True' ,, A ‘ True" True True 16% True /\ False 61$ \ Fals\e .61}? False False J False False ‘3 False Fals 9']. 9. (20 points) (a) The molecules XH and YH below are weak add with regard to dissocation of the Cm—H bond. However, XH is a stronge han YH. Please give the reason for this, assuming that the Cm-H bond strength is equal in both cases. o H ‘c‘: /&; ,H H\H c/H . / \C/ \C - 1 $9 H h H/ILI‘ ll I“II\H /% 9 fi . “x ' HY Cwst ’Nz (Norma mew—'7‘! oI- W1 emu:qu “2423:. x' A~o y ’ '1- o o + - ' 'f" " \ a" "i L- s C “ ,. .. . / 'C§C/ \C\ H I | 1 Hr u / H H 1" '4 H 09E ({QSopA-nCE STRMCML ., 12 kr’l 9. (continued) (b) Write a charge balance equation for a system obtained by mixing 0.1 M NaCl and 0.1 M MgCl2 in water. , _‘ I it: i I ~_ rv i , " ' [116(14- A’ J + e lCtJ 1' lOl‘l' (c) What equation would you use to evaluate the temperature dependence of the equilibrium constant? (d) Extra credit (1 point): Please draw Ludwig Boltzman. l3 10. (20 points) (a) (b) (C) (d) (e) (f) (g) (h) (i) (1') Circle "True" or "False" for each of the following statements. No mass is created or destroyed in chemical reactions. W A blue transition metal complex is less likely to be paramagnetic than a red complex of the same metal. NH3 is a strong field ligand. Anodic protection can help in preventing corrosion. Fuel cells are concentration cells. Arranging your books decreases the entropy in the book cabinet. The most stable isotopes occur when the number of neutrons and protons are equal. Increasing the temperature cannot change rate constants. ’ Enzymes are used by the cell to slow down fast reactions. Spontaneous reactions are equilibrium processes. 14 True fire True True ll True True True True False Fals ‘_/ False ...
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105bf07_sample_final - . - “smite HM 1009 iChemistry...

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