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apcompexamkey0809

apcompexamkey0809 - NAPHQhemistryfle,Eleotroohemistry...

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Unformatted text preview: NAPHQhemistryfle-,Eleotroohemistry, Nuclear q, , Chemistry, Comprehensive Exam Name: Date: Period: apelecnuccompexmosogdoc Show all workvto receive credit. You may use your book and notes on this exam. 1. A standard electrochemical cell is made by dipping a silver electrode into a 1.0M; Agi' solution and a cadmium electrode into a 1.0M Cd“ solution. a. What is the spontaneous chemical reaction, and what is the maximum potential produced by the cell? ”ganazgygy fifaaa : ~0.7o l/ w ‘ v Flam.ro~('0»¢&)‘ ”W {47! ‘ » ' ~ 2+ Reaction: 0? I? + + 6%,; “59’43‘” + Cd Cell Potential: /‘ 2'0 V b. What would be the effect on the potential of this cell if sodium sulfide were added to the Cd“ half-cell and Cds were precipitated? Explain. [a or] Pmufrial-z‘ [,(zr out“ ween/d gm~éz¢ 36:4“0f72l549 0-015er whim. Wiley-ob Q$m£lur ' . ’\1 Q X l, M . x +M¢fm . , z a Is reverie flaw ,stl c. What would be the effect on the potential of the cell if the size omits silver electrode were doubled? Xn/ TIM/QQHZ SHVEM aria/travel». )‘5 ”9+ PM ’6 G) 3 +MAN‘Q. [41m 13 m ’ @FM 3 , 2. In an analytical determination of arsenic, a solution containing arsenious acid, H3A503, potassium iodide, and a small amount of starch is electrolyzed. The electrolysis produces free iodine from iodide ion, and the iodine immediately oxidizes the arsenious acid to hydrogen arsenate ion, HAsO42‘. , Izraq) + H3ASO3<aq) + H200) -> ZR“) ‘9‘ HASOqZ-(aq) + 4H+(aq) When the oxidation of arsenic is complete, the free iodine combines with the starch to give a deep blue color. If, during a particular run, it takes 65.45 for a current of 10.5mA to give an endpoint (indicated by the blue color), haw many grams of arsenic are present in the solution? [0,531.14 1: , 0,0534 ,’ . 01051.2. (6645's) I i5777/5’ Q :7 ' 793wa #772“ (lat/wig” 2:31: ); 3.57M!) H Answer: , ‘ 9 As 1 V796 3. S’IX/D"M‘(7%9Z’/M);V 163*” QM); 3. Under standard conditions for all concentrations, the following reaction is spontaneous at 25.0°C. 03(9) + 2H+(aq) ,+ 2C02+(aq) -) 02(9) + H200) + 2C03+iaq) . If [F] is decreased so that the pH = 9.10, what value will Emu have, and will the reaction be ' + , - ll 3 , , - spont:n:t:.r;attl115[H ]? ?H‘ 9,10 [Ht] 5 M I” /p d M 1, 7’ ”3),” 1v, . st‘ggw~ ‘fi”, 10363 , i 5+ch¢ (Marrow Ivy/m M‘W‘)’ chMM‘fW . «m, l ([7 tram"? 1’) ° 2 V ll" n“ . 7/4 \/ . EC... = V Spontaneous?W_s_ 5" —= 2.07V 03" mo Fox: .ZS’V’ #3357 5 i ', 17V air Var/V .i. (Lem/7W 4. Consider the following cell reaction at 250°C ,, , , , ,, , , 2CP+(aq)+32n(s)‘*) 32,123“), +, ZCi-(s) ,, , , , , , , , ,, 3. Calculate the standard cell potential of this cell from the standard electrode potentials 50044.,5” ,2 -odav cf... 3 “0.7“” . ~9Cr K3 , .... .. ’ E0 0 .08.. 0,77 +0.7e-.oz,\/- an. E can = _______________________V . b. From the above cell potential, calculate AGD for the reaction. l/ —. 34‘ 0 456° 2 “HF?” X5 I - 10% 4/901- szv) C " 37" AG° = “I. 1X 1’0 k] ‘ ’ Vials." ’2: ' 1/ S 7?. e . c. Use the data from your textbook appendices to calculate AH‘3 fofthe reaction. CY g: 473.. SIB/We DH; 4W: (hi 5+4 Slingao ‘ ' 2,473: “/5317 SLY/M X3 0 _ / 71$: 7 ' A ll' raga—253.4 fl ~[(2)(»z¢/3..€k37..¢)j AH =_________________________~_____ld :1 "l7lz’17k3' d. Use the values or AH° and AG" calculated above to determine AS" for the reaction. ._ ‘ A6": AH"-7’AS‘ ' ...~ egg; (+3319) -//g77,4. J 1'— * 17% 7003— —- 2598,14;(AS’) in) ASO=WJIK l6.3./22.‘/ r: “mas/$751233») ASA: ‘54/7j/k 5. Balance the following oxidation-reduction reaction which takes place in basic medium. ,flrsMfi (99,1369M“) 02:4. ”ll/2,0 7 mo; 4— I' —-> Mn02 + 103‘ I ‘4; 3M...) 1‘03 "‘ 3‘ éH-fi + ‘5' . , 4 .— - . 3y++2mo ”be” .aZMnflz-f W50 ; ' 2” +~2”"§", 41. ”16:?" +~V’"03 ‘1‘ 1/717 ‘1 . tam-em v 41-7 *Ioawmww 204’ X" Answer: ”2 0w 4 2M») {91' 2:3 2" + 1707?“,1‘053» Jr 2M» 02.33 + 20H 3 2 6. Polonium-Zlo has a half-life of 138.4days, decaying by alpha emission. Suppose the helium gas originating'from the alpha particles inthis decay were collected. What volUme of helium at 250°C and ‘735mml-lg could be obtained from 1.00009 of palonium dioxide, P002, in a periodof 48.0h? 80;: zy'lg/mfl, been? ./w,5h{ '1 JOY/9’9 we. foal... = “WV/79"f )6 ,l - 1' ' . , .. , a . 9 ,. " 3 ’“ 0’ 5 . 0( fg/G'j")?v)‘rp,,4¢x,0'51’.ot23)(2&3.1le3 £5: - ,é‘ 31¢ , K .. v593fl3~7H '005‘7 . . . _ v2.00) )h £1) 1., kl. ,[n (Mat/NM) :anscoXfigAas) )3 Answer: '00! ‘L ' N“ i " ‘ _ _ AM : .ny «1'? ’- .wwos’: 461,54 was: X a. , a oat/051M Mt ‘ 7. A sample of sodium phosphate, Na3P04, weighing» 54.5mg c0ntains radioactive phosphorus—32 (with mass of 32.0amu). If 15.6% of the phosphorus atoms in the compound is phosphorus-32 (the remainder is naturally occurring phosphorus, how many disintegrations of this nucleus occur per second in\this sample? Phosphorus-32 has a half-life of 14.3d.® {2L 2: . (.‘ij/k kn , 573/ , a. v _ . . ~ -= 36"‘77 37»? PM“! /,' i3 5'5'20 x20 5 ,‘ as 1 ,. , g y ,. ,6772. 0 paw; 1.030%): 5’ ”My @4559» r L... we ./ M » )0 ;< emu-Ha“; 3, homily... M 9509? k :: S740 ‘IXIO'J’Q ” , 4' l3 5' , W ‘ , Answer: /‘7~" X ’0 disintegrations/second 030 VZ' «W993 + (I. lngzzlaéfVC/le/tn] + 405%???) g ”"1 560 .kN2(amofiw’fidms‘lls.(firw‘75"):/.7§EQ_.I3 Mflw Mg ‘7 [é ' ‘73 V: 3% l¢?£: w: rd 2* L33: ”jade; 5L» 8. a. Plutonium-239 has been used as a power source for heart pacemakers. What is the energy obtained, from the,,,foilowing_ decayof 215mgofplutonium—ZBQ (Pu-239 w=w239.05216u; Her-4' 24.00260u; 3 11-235 = 2353439211) —y,...,( Q) ' 6, 2 l‘§§)( ’W%3g%—2/é331£79q1(92 ngu—egHe-i-ZSU -~a 2 35') 043577, AVE: ‘ ”gel/“firm (e. lie/miWMIG’O‘WD‘WM/M). 23105“? \3 “mo .27“ : “WM 6-27 / > -= sqlgxmmarms / 7, 302%?0'39%A+m\ '3 5.67/x/o”‘ikglolal . 06%?“ ( Mum} kg M 4 a , .. . 2 ‘ v ’5 Answer: ' (/rSZflXZO 5' [email protected];@ov1¥/o 9671?.aaxmi’9’sf "" q 34 X/o ké/afim )g 7 , 3%5‘635~23’ i (use W) b. Suppose the electric energy produced form this amount of plutonium-239 is 25.0% of this value. What is the minimum grams of zinc that would be needed for the standard voitaic cell 6’ . Zn l Zn“ ll Cu2+ 1 Cu to obtain the same electric energy? <21, 55 m)! 3' C 255;) r: 4/4110 ‘3‘ , /./0v ’3 M03] , , ‘ ‘ g a. , [3.” 65: 39 2,) Ea .. 1/ 0 I’. i 93” L9. imw" I W 24” 1’ 0'74 E = 4 3 ”(lo (Mair aggroc W’ {1:11;} a?" C4513” 0 7 V )0 Answer: Eng/KM? gzinc 33921201; E311 : 03"“(‘01751 /,/0\/ (as. I 1%) 9. The half-life of icium-47 is 4.536 days and it decays by the emission of a beta particle. a. Write a balanced equation for the decay of Ca-47 . . r 0 ‘7’ 7 K” V7 ”we + Answer: 7'0 ‘L’ "’ fl 3*» ' 5c b. If 10.0pg of (Ia-47 is needed for an experiment, what mass of 47Ca$04 must be ordered if it takes 48h for it to arrive from the su iier? , 5—, . é 73 — , ' 2 -2 9’7 .2 .3239? , A V534 " ’5 g ”(“3 2:; M2 —- 173,243 , . m. A. M y , ’3’5quj/,32~25 7‘ - ”1""- : é .' f N t . *9' ,, 2, ./§;9){2.o) 4—3 = [35'7" . X9 Answer. 17”!" P ,, LAM/0 g 47Ca$04 .. {n .313ij ( M. on; 10. Sulfuryi chloride is used in organic chemistry as a chlorinating agent. At moderately high M a ’3', Q“? temperatures it decomposes as follows: _. ' SOZCiZG) <——> 502(g) + (32(9) ‘3, 2,5 2 502 C]; (391.96 3 {é/wf Withl<c=0.045at650.K. » [EL/3&3? 3/” r. ‘061/ a. A sample of 8.259 of $020; is placed in a 1.00L reaction vessel and heated to 650.K. What arethe equilibrium concentrations ofail the species: K __ [30;] C617,] 0 073‘ (>000 _ ‘ C ’ [$0.010 ' (. ow- x) ,{V . - X a . 0 34¢ '1, ' f- X {h ) [50202] = WM; [302] = A , 0 3 V6 M; [02] __. am 7/; M b. What percentage of 50202 has decomposed? . 03 ‘/ é. 2‘) ”a : . 06 I! i ’5 55A Answer: % c. If 5.009 of chlorine is inserted into the reaction vessel, what qualitative effect would this have on the A/ . , X ‘3 Til": will doc/west 7‘“ 4W ’5 50;,0/1 flea-mp 01:43 11 The following data were collected for the reaction A(g) + B(g) —e> Products A _[[0 03012:} 7([0. By/W‘K Experiment [A°](M) [BoKW Rate (M/s) ’3 0X10 1 0.0100 0.100 1.0x10‘3 :j'fl )7 2 .; 0.0300 0.100 3.0x10'3 / own [a a: to W 3 0.0300 0.300 2.79010-2 a. Determine the rate law for'this reaction. I V A 2 7 K , 0'? ., k [0 xow‘ojCO 3’ij A, ” . ‘ Lox/o 3 =— MILE; 0300] [0 [0’0] X [do :1 /< [:43 [3.3% v _ 2/ Answer: . - . , GI. ”.22 '3 , 7 " b. Calculate the rate constant. _ 1' [<— [0’ 070038) .300] p 7’ ‘ 3.7m :- Answer: A 3 [0‘4" 5 ‘ " 0. Calculate the rate when [A] = 0.200M and [B] = 0.200M X3 _, ,7, M ,. flak 1'0““ S'l(0 WMYQ 7411)? Rate = f’” X N9 / , 12. Tungsten has a body-centered cubic lattice with all atoms at the lattice points. The edge length of the unit cell is 316 5pm. The atomic mass of tungsten is 183. Bu. Calculate the density of W. 26.47004“? 7‘4/01'0053CI ”60(10 ”3/” 6 Iowa” 190476“ _ dswfv ~ “"0“” “5/3 mm 430.33 ”H.109 @L‘LC = :19)“ , ga}wofl@li @. ': XI) Answer: (01 15 g/cm3 twd/W \/W “(3 [05' 51:03 on) * . ~ “’3 mm 13. The vapor pressure of benzene is 100 OmmHg at 261°C and 400. OmmHg at 60. 6°C. What' is thew a boiling point of benzene at 760. 0mml-lg. £7... #3, p/w 5/145 A {:1 At m 57 My,” I“ 790,0 333655,? J. ’ J.) F H! 1017.6 as“; 1% 15’ T ' _ A. ’ , 7;: $9 5714 352 571271,)? gm /“ pf - 75W(_7(:’7‘: flca’K/V/Hflk . ' , -.— 3 45.? )(5 Answer: . 7? °c /y,(‘/7”3 ()3): fig” J, __ J, ‘ Amt}; 3' 14 A molecular compound is composed of 60.4% Xe, 22.1% 0 and 17.5% F, by mass. If the molecular weight iS 223u , , ', a. Draw a Lewis structure for the molecular compound X‘: I 3” 2513 5) ' / 5 ‘9991/ F ’ “’99? K0 :Lzax 1.07:7”)? #0., 213x,~227:3.03 F3 2231.175 1. l31.2’13 _ IS" qqqq 'x’l' . .. . b. Predict the molecular geometry in terms of VSEPR and valence bond :eory\ 4/ ‘ lb 444/ W kWh/W03 hw— X W4) ’5 3’34! éflao‘td/LIM ...
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