105bs09_warshel_pe4

105bs09_warshel_pe4 - Chemistry lOSbL First Letter of...

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Unformatted text preview: Chemistry lOSbL First Letter of PLEASE PRINT YOUR NAME IN BLOCK LETTERS 11:00 am. Section Last Name Fall 2005 Name: EXAM #4 November 22, 2005 Last 3 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 F—“‘ POINTS '— 20 20 20 taking this examination. 20 l I I I INSTRUCTIONS: 1. There are 5 problems on 9 pages in this exam. Please check to see that you have a complete exam. 2. Please show all of your work to receive fiill credit. 3. You must use ink. Do not use a pencil. Answers written in pencil are not eligibel for regrades. Usefixl Physical Constant: 1 Equations: Avogadro's numb- N = 6.022 x 10” rnol'I Universal gas con at R = 0.08206 L atm K" mol" = 8.314 1K" mol‘l Faraday’s constan: F = 96,485 C moi" KP=K,,(R'DA" k3=§ -b:t b1—4ac Ifax2+bx+c=0fienx= 2” PV==nRT -w=q§ AS=kB In W 130:-an AG=AG° +RTan AG=AH —TA%’ E=q+w AG" = —RT 111K“, ‘ a; o.‘ Additional Information e=e°-‘-§1InQ 1 "J v AGfld) = —96.5 n 8 (volt) ' \_ I " A ‘ 8° volts H eactxons , "~ Afjf‘*l€‘- Fo(5) :CLQMA» Cu+2 + 2e’—>‘ Cu(s) 0.34 Zn‘2 + 2e‘ —-> Zn(s) -0.76 Ni” + 2e‘ 9 Ni(s) -0.23 Mg+2 + 2c‘ -) Mg(s) -l.03 ca’2 + 212‘ —+ Cd(s) -o.4o Sn“ + 2c" -—) Sn(s) -O.14 MIN-I- .n'uhzgnf p. :: , E I; I: 75 n 77 7| no " .'.-. In On 1: Pl 3. .‘in‘ uuw nu: man nun nu. fins} E “n no H “2 w r... a“ nu - n— O 1020 Appendix C / Thermodynamic Quantities for Selected Substances at 298.15 K (ZS'C) AH; 110; 5‘ 011; AG; 5' Substance (kl/moi) (16] /mol) O/mol-K) Substance 01]] mo!) (kl/1:101) (J/mol- M Cobalt ‘ . Magnesium (30(8) 439 3g3 179 Mgfig) 147.1 112.5 148.6 Co(s) o o 28.4 M80) 0 0 32.51 81303:) -641.6 ~5921 89.6 Coppe, 8130(3) —601.8 -569.6 26.8 01(3) 338.4 298.6 1663 M8(0H)z(s) —924.7 — 833.7 63.24 Cu(s) 0 0 33.30 CuClz(s) — 205.9 — 161.7 108.1 Manganese ; cu0(s) — 156.1 — 1283 42.59 M1113) 280.7 238.5 173.6 5 Cu20(s) —170.7 -147.9 92.36 Mn(s) o 0 32.11 3 Mn0(s) —3852 —362.9 59.7 Fluorine M0026) ~519.6 —464.8 53.11 Hg) 80.0 61.9 158.7 Mn04‘(aq) —541.4 -447.2 191,2 F'(aq) —332.6 —278.8 ~13.8 52(3) 0 0 202.7 Mama-y 1-11=(3) — 268.61 —270.70 17351 113(3) 6083 31.76 174.89 113(1) 0 0 77.40 Hydrogen HgClfis) -7.30.1 - 1 84.0 144.5 11(3) 217.94 203.26 114.60 143,035) ~264.9 -2105 1925 11*(44) 0 0 0 111(3) 1536.2 1517.0 108.9 Nickel 111(8) 0 0 130.58 191(3) 429.7 3845 182.] N19) 0 0 29.9 Iodine 1910135) —3053 —2s9.0 97.65 1(3) 106.60 70.16 180.66 N100) —239.7 —211,7 37.99 1194) -55.19 —5157 1113 11(8) 6225 1937 26057 Nitrogen 11(8) 0 0 116.73 14(3) 472.7 4555 1533 111(3) 25.94 130 2063 811(3) 0 0 19150 NH,(nq) —8029 —2650 1113 Iron NHscg) —46.19 — 16.66 1925 86(3) 4155 369.8 1805 141-1301;) - 1325 —7931 113.4 86(5) 0 0 27.15 Fe"(aq) - 87.86 -84.93 113.4 19,1143) 95.40 159.4 238.5 Fe”(aq) -47.69 —1054 2933 191-809(1) 0.0 _ _ FECHS) —341.8 —3023 117.9 1911.016) —314.4 -203.0 94.6 NH.N0,(s) -365.6 —184.0 151 FeCMs) - +00 -334 1423 N013) 9037 86.71 210.62 160(5) - 271.9 —2552 60.75 86,0,(5) - 82216 —740.98 89.96 N043) 3384 51.84 240.45 5630.5) -1117.1 -10142 146.4 1910(3) 81.6 103.59 220.0 Fes,(s) — 1715 - 160.1 5292 19,043) 9.66 98.28 3043 Noc1(3) 52.6 663 264 Lead 1~INo,(aq) -206.6 - 1105 146 Pb(s) o 0 68.85 HNO,(3) — 1343 —73.94 266.4 PbBrz(s) - 277.4 -260.7 161 Pbco,(s) — 699.1 -6255 131.0 Oxygen Pb(NO;),(aq) — 4213 —246.9 303.3 0(3) 2475 230.1 161.0 PbO(s) ~ :173 -187.9 68.70 0:13) 142.3 163.4 237.6 OH’(aq) —230.0 — 1573 -10.7 Lithium 1120(3) —241.82 ~22857 188.83 15(3) 159.3 126.6 138.8 H100) -285.83 —237.13 69.91 11(5) 0 0 29.09 1110(3) —136.10 — 105.48 232.9 Li"(aq) — :785 -273.4 122 H2010) -187.8 —120.4 109.6 Li +(3) 685.7 6485 133.0 LiCl(s) - 408.3 -384.0 5930 l. (20 points) (i) (0 (ii) Using the data on the information half cells of: Zn(s) ——> Zn+2( 1M) + 2e‘ Ni(s) + Ni+2 (1 M) + 2c- also determine the potential (8°) for this cell. Walt, = (DC/.4465. — .- Based on the data on the information reaction Zn -> En'u'fiiu- page, indicate which is the anode in a cell based on the f ’0' mag‘l’ M”; a. S‘ o M 5 o is Fuh‘h" « “’7 v0.25 M; ‘9 IV; 1* +—2e " SWIM Ant/MM page, find the equilibrium constant a} a? for the +0’76 412*},24: 9 a #flAbo +0.34 : 5° Aer— —m F2”: 42mm M: .2 me o F: ?5 $495— = 15.8 R = 9.3/4 J'M'k " T’= 276K Ak 2230.6 up W k‘ e 2. (20 points) (i) Please draw the electric cell formed by using 00001 M CdSO4 solution and a Cd(s) electrode and 0.2 M ZnSO‘I and a Zn(s) electrode. Determine what is the anode and what (ii) Write down the anode and cathode reactions. a" ._ _ a 76 __ 0.0572 / C) M: Eu{s)—9-Zn1++22- Mam: (2’5, 25—90115) 5‘5! = "‘73 => “(#5: (iii) Indicate the direction of electron flow in the wire. W) w a 3112. 4-D Cal .S‘I‘oa- E = +0. 73 30 6‘” (iv) Calculate a for the cell at 25°C. £1...) 2—,.“ +2? +0,78 a“; 2e” —9 a '0‘52' \” V = (v) What concentration of Cd+2 will allow you to change the direction of thg current in the cell? K .254 64;”: 0’76. 0 3,4. ' .940 E=o=e —— W2- Cew J an at! 2. Eu & 1,, J . I? [Q > r‘ 4' o t 3 6 ' ’Q :9 -036: _ 0.0 2. (a 2M) 3. (20 points) (a) Circle "True" or "False" for each of the following. (i) Cathode protection helps to keep a constant temperature in buffers. True (ii) F2 is a good reducing agent. True 0 (iii) Biological systems use electrostatic processes to \x 8 ’ perform their work. @ False (iv) When AG0 for an electric cell is zero, the emf must be zero. Tm" (b) Draw a battery and write the corresponding chemical reaction. W: 3’1 —’ Zn 1+ +2: '- mw: fill/#1,? + 2M”; +a?e‘—> My”; ” 2“ , *' I \ V / M (3») I muff m UVMI 2””pf—f— aneL’. &a,>z‘1++ M", fl3+ ZNHS ’L’L/p 0 (c) The potential of an electric cell is 2.00 V. LWhat is the maximum amount of work that can be performed by the cell? and H- I}. valws ¢ #Msér m0 2. e/(dnns . HIM")c ; ’ 3— 2M”: 7’ ’M Fgmx “(2.) (qé: Vaga'n WWAX "' uni 6", VUW‘AX €- ’ 4. (20 points) (i) G. (S. x36403x (ii) 5 zit—Re- —9 Fé How many grams of Ni will be deposited on a metal plate using electrolysis with 1 Ampere current for 3000 seconds? la”? :/ don/M See [me 8.)! “We ll/o. 94,5‘81’0 2M6- Will the coverage of an iron plate by Sn prevent corrosion? Explain and quantify your result using the corresponding redox potentials. [.67 wi// Sn rem 343$ a 7 I 3.4 —a 3,.“ +2;- +04% —o.</‘/ ~0.So 1/: (5;! i A43 . 0441:7‘ é: [ts/711‘!!! 4;, if 4. wwf, M 435/2: wffi‘wv 5. (20 points) (i) (a) What are the electronic configurations on Fe and Fe”? Fe [Av] 431.2!" , 0 —'%¢ ¢. CE 52+ [Ar]y6 (4:7: tariff»: 5:44”. 7’41). (b) Explain why the oxidation potential (M ——> M2 + 2e') of Mn is larger than that of Cr. (You must consider the corresponding change in electronic configuration.) H“ [34...] 4313!: '9 54"]34/5-15 1‘4an (57 Cr [1417433456 [Ma‘s/“M 0” / oankl‘s W5 J‘MMCr-‘I‘. (31/:st 34¢). L) 02+ Mg; M’MJKsWVIM- (ii) Circle "True" or "False" for the following: (a) EDTA is a polydentate ligand. False (b) The d orbitals are being filled in the transition metal series. @3 False ( c) The lead battery is used in standard calculat or: . True (d) Electrolysis can be used to produce 1-11 from water. False ...
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This note was uploaded on 01/06/2011 for the course CHEM 105BLG taught by Professor Parr during the Spring '08 term at USC.

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105bs09_warshel_pe4 - Chemistry lOSbL First Letter of...

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