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Unformatted text preview: rnnt Name. Last: First: W g Page 1 Disc. Instr. Name: L141de 62322»: CHM 2046 - J. C. Horvath EXAM 3 _ I _ _ Summer 2008 INFO: Same rules as for Exam 1. And this exam is worth 183 points. - Thus, up to 58 extra points can be earned. 1. For each of the following, write correct eqns for the lAz-rxns and net redox rxn. (Note: Partial credit can be earned for each correct Vz-rxn even if you cannot get the correct net rxn.) a. Cr(s) reacts vigorously in 6 M HON02 giving hexahyd rated Cr(III) as the oxidation product and N20(g) as the reduction product. 5 (0154,) + exam) 4? fieéWflf-i 3e“) (8) 3 (m g‘g’ofi‘fl‘i' Z 3 1“ 9'6" we) 1053.553 4' {5&0 m) _ 2? 0: (.4) +— 3 #20 (12+ 30 agate...) + g; mafia)» s] a. (daily + swing ‘J b. Mn(OH2)52+(aq) is added to a strongly basic soln of 1 M KMnO4 giving a precipitate of manganese dioiide as the redox product. a4 .— 3 (ggjq— H W555) ""§ M71825th 'i' 26‘.) Sign Name (Pledged): (3) _ ZiWOarag-rzumu «i— statement? (3-H- ‘fHé‘ic a] 3 M11 {0fl1igzzrmf} Jr 2 MHKJJ-(cz) +- Hflfé—gl "3" 5aMu02M-3) + 20 H10 (I) c. AgZS(s) reacts in l M HCUHOCI giving a _white precipitate, H0503] and no gases among the products. .4315 (a) + (I file Ce} 4- 203:5; —> 2 65am 4- 7 ageing + Hfiflgicgjd- 9e" (3) 4( #30?er 1" “Mite 1H" Zef—"v? gal-Leda}? (fir-3)) __ 4,;152424— 1-! young; '1‘- 3H306é} -? 2143604) + BHBEfiszi 1" 950a few-i” 25%;} 2. In conjunction with Q.l, above, answer the following questions. (Note: Consideration of information from the 1Vz-rxn list on the INFORMATION SHEET is necessary for certain oiWse questions.) (i) If each of the rxns in 1. proceed to completion, on a “per mole basis” which system (a., b., or c.) should become the most acidic? How about least acidic? Defend each answer. . - + - C: Wm heme Macé'zétgcm Mfixm BMH‘JG W'Wi 632.5, W-idififidj (m) b, cad-1H he .25»? acidic fV-“w dwq'fiw} mm Wmfilroflgiw 3%“? C- beam W :2. 07(0sz Wécfl w— del acidic 44mm 01?“? 6') (ii) Although CuS is somewhat more stable than AgZS, the oxidation of CuS in l M HCIKHOCI would not be as vigorous as the rxn in c. Why is this so? 5' M magma {fie/um ail/five W mmVWWM 6g 471$ 5': W (6) 4*6LM6) Miéflzubie @C? (655’ oxidddm-s WM Ca {674,26 M. at... can‘t; Wdami' bra-{ca v3 .441» 44;“: {ion .4ch Em yz'fidaas ~zq_4umzuga (iii) For c., tell why Clz(g) isgogobtained asa. reduction product. (kw? “an 3L 49-32, Em Ntng’fiblcfi'.) Ci}. {4 a £171 W identifiable firm #06:! 3.a. At NLC a molten metal chloride is electrolyzed with a 6.70 A current for 1.00 hr to yield 5.01 g of the metal at the cathode and 0.125 mol chlorine gas at the anode. Identify the metal by calculatiOn of its a“ (molar mass). Show work. (Hint: First calculate mols of metal produced.) awe 2 a?!) r"? C371 (5)“? 26" .1 dumb. 0.1-zs’fil1-w4’f'wiliee was»: We!” 5;.) Jasmin. Jmmwm be MCI an no,“ M13... met. 'tn'ilvitétwham W (8) 5.0]? M :3: 5,25th an 6J2.be (3J1 0.10.833m14 an a, Oéig‘wfi’w‘ .. r;- _-, -. . am cm £61.12 . so. Wig-3M *Mb Anti“! 2€»09}/M( 6’1 331??! we? Mmh akflfl,“ b. Had the same electrolysis been performed on a molten metal oxide of the sa emetal how would the volume of oxygen obtained compare to volume of chlorine obtained in part a.? Defend WlthOllt any actual calculation. chupd Wmlc‘i M14 Ca 0 twill? New ewe! killing-2 OlzgfiLie-D (6) W.A”¢S!K5,fi Li 0:150 Gawain/1AM 0.062.517.5533 01(5) 0‘:— K ‘LMfinx filigrw‘fclL : 0.:DblS'M4-JZ LEM/£5,“ (6) Print Name. Last: "It i g gf First: W fifij Page 2 4. Write the Lewis structure or Cl3CCH2CHNH and “parcel” e"s to determine the correct (0) no. for each C atom. Show appropriate work. C.’ {L H . ‘4’“! ‘T‘. a- _ . (8) C'le-JrC-kcész‘ Cal-#44"; +3 CfQ—ez—Z ’r" .1. H , i c: H 324-4241. 1 2. '3 5. Consider constmctin an electrochemical cell which operates spontaneously by coupling l/2-r1:ns 19. & 23. from the INFORMATIO SHEET. a. Write the eqn for the net cell rxn and calculate E ° cell' 2(245u)+ Has" up + 'zlsvm.~1> £31544) + 2 sow-«r 2e") 44. 027 V (s) 02a) 4 2 H10 w a was, true??? +moxf W #613”) “r 2511/5“? "i 5 H206“ + 0;. 1‘5) 4) 2 Ayfi'im 4- QigOiap-t 4M"? 1). Calculate E can if the anode 1/2-cell is operated in 0.10 M H28 and the cathode l/z-cell is operated by bubbling air (at P(atmospheric) = 1.0 atm) through pure water. (All' is 21 mol% oxygen.) Show pertinent work. mm 41,; fig“: Liz/(£7:- MMNWJ : 21430”); (1m - fer“? a. w _ ' .. 9‘ 1;: +0.43%"— éflvhj W) I (15) 1+ fit; 32' (Post?) + one)? 1/» aofiV 2c; ((1435,: :o“’)q(k.a : ah has?” (0.2!) 4“ 0 .437 V" x 1042) A 4. may!) V4: (3. 605’ V: V H; .. c. For this cell, can C u(s) be used as a suitable electrode in the cathode I/2-eell‘2' Why or why not?I 52L 93"]me M Mr}? W Cu cam £2 «255.55% 0;». :5; l'z-ca/f (6) ad'gvH 7w (rape). 0.2: a)... m) MJM 59ft!” :11 am? =Wc£ ‘92ch + 0,9} w. 023;) M W'ieam afffiq-wlw TM) we ' cum am Mm Meaty—3.43%.. Why an MWJze'ble M was...er d. If oth 1 M H4NC1 and 1 M H3N are available, how should this cell be treated with either, neither, or both of these reagents to up E a"? (Note that AgZS is Er more stable than Ag(NH3)2 .) Explain your answer. .-. [affix-3.4 e’pghduiflzfljmefi We Wdéa flgagoel MM 3.1m": await?“ fixer) 733W Wet-9 Vi'a M w. [mug/v w.) M 1!» .mwma ’f‘ w km, (12) "' i/g‘fi'zm 2'7. WMalw "ts/swim weld;ch mule/1 ea‘aiic (Andy- kW) iff/wm ‘15.) 0’1 lad/ME (How/11 23,) ouwdwn A20 W12 Pagan w- wildly acid?!— H"! NHNCI will (also) ‘l\ {M Eu” 6. With ap‘propriate electrochemical arithmetic, calculate Kw. Show work. (Note: In doing this calculation use 0.0592 rather than 0.059 V in the Nernst emu/F; , Q' E : W 1’1, . : '0‘ + m m Z3 ‘93-'79 + k... = 1< 4:“ mm see? c so; 3:: ' mad-r e"'—+ I/gszgl-i- Hafiz) 2‘: was 1/ ‘3 (10) 115134245) + ladle) 4; 145:??3'14—6” E626!er I 3 519w 119+ 243602.323»:- Hfifiy E”: —o. 931/ '§ S Ea” :: O :2. waist/a» 0:0562V(?(2u33+_‘] £91512) :3.) 1.3%,- :flwa W 4" war 262! 1 Mm; «was'xw’ j Print Name. Last: ' H 2 a First: VV VHS-ZS Page 3 @cmsider: LE.H)(Na) = 49 lmoi, 1.510301%) = 4562 lemol; LE.U)(Mg) = 738 kamol, LE.(2)(Mg) = 1451 Miami; LE.(1)(AI)=578 kamol,&I.E.a)(Al)= 181? kJ/mol. Use this info as necessary and reflections on Zem shielding(S), and e_-penetration(eP) as necessary, to explain or tell why: a'LE'(1}(Mg}> LE'(I)(AI)>LE’(I)(N3)- \M. Mg: 34:34? :34}? pi; N5 33,41 bit, €34 apex". K4534 (HIM 3P cam) mfl drawn); £41.] fiat-3w? 26H; 41“” 319' (Al)? {We} ELL, evw&.e Ema“; Na wesivealm . 3'46 I Z=13 /. W 34 at? (142?“ , [5);4641WW.¥M all '11:; 6'11: M (22? N12. (5)51 15 {M97 me (but) m ‘h’ i 34 6"4 A4:me “n+1 €33; be I ‘ u I: ‘1 'r , i ' ‘. 4% $34!?“ We? 7:ng Lad}? ) LNG) >> (/30 bee. 1’.ng Na awn.” 1m cf 219:9" wind: 7/114- Waxed M1242); 'Wyol “MAM My 1133 er mi 3, exmhenw 'Irmdt W 2'44 “Vim”. my (10) ’14 7— 3 e“: (Alleged?) bee, 12:2,“) M Jamie» {mag 34 6‘04 W 115m My, bad) Wu (5’); [tpyam den-figmeiaf 29% 41v. A1343— ”? 29.4251 girl 1’4? 343‘Mm 2 (ziajofiw m ? %(=12)aG¢a M; /$’h3§,mm5v5 8. USe LS’s as appropriate and discussfexplain fl pertinent factors which relate to the following}; ' €— 13} Ma ) a. H20 isastrongerBfL acid than CH4. “join (Wale; \ gfld MWOQJWWAWMMW 51H“ “his I 8 MM C} 0 [3-5] 3% C(15) dink “(61,194+ dc 'de gum ewes” «Wee-use dag- awe Off») on 2566‘ ext. Ho 6mm“; H36 5W4 Many»; 32L 5m «qu H? “M; 2,? my. b.HESeisastronger BIL acid thanm’tfi-WJ) “up ‘4 GHA mm CHM] Cum, flee w. H09. : _ K 0 ‘Vm’ifi EM £41m 53(Efiflz.é)) Ed L4 'Wc‘fl (3) ‘ g ,5 ,4_- we was anew) wafm'L-éi Hewa‘uwefi (M Mped‘e o'm ' 6' I, . yum Nip swam" 5 mega Ur. m: 014—.anij Chg/mac We —r *3 Hzfe~M¢PW (Laid “if-1M H10 c. HOSOK:3 is a much stronger BIL acid than H4N+. (And, comment on the unusual Coulombic aSpect of this.) a 'l i a" "' o u . ' W4... @- ‘gflfievg- {hi}?! ‘1 50:: I4 ::2 Wauwfidr H3119 ‘4 'Mdhfii, a? 10k T" H #3” > NC—P of «5'04; 13.2.9, 1 3331 ms) NC!) :4 Whahmi wfiaé—ificb 97 11;. \EWOIJWJJW- %£WUNCV Metre”le- by Women: cumd’tw 50:;- a: Wfiil’d {’gmwfi M ecpfugi-iw Molina Wlmmayadca Juadumiuxqa {m wdwf _?mb'dMLT_um1W {Mmmiflmfifib} 4 . 6'? HQNGB (A waif M My»? 81L MAJ 6X4— Haw; what, {A {mammal} g: : d.H2N2isastronger BIL arid}? [LIL-i; “M ‘ ‘ I g 5 /' a TI?! - 1 . ._ __, \. .- fl, _ 6A,) 1:5 m- {V‘Nx- I N-"N Q '45 N—Nx ’ M J o‘ 6 i H H’ ’ ~ ’ '\ i4 H’ 1: A ‘2: NC? hatter: “um @MdeUENHEE i 9. Provide rationales as to why A] 2)63fisamuch stronger BIL acid than Ca( 962+ whereas Tl . ‘ 6 +isa much stranger BIL acid than Al(OH7_)63i. fi'9f—CP Calfm‘? eadfi W. 6” 34' Wf,‘3€’—®‘~WI¥C u). Ne 4- CARI/ea clad/waft; w- '3’»; 3;: ®d§’ D (Tao) 'ffllwy (12);> PCO Chaim; {an 1H? HOG-L da' 9615 w imam. 4' My: MMEJMMW -W\A§V§®fiawm 31L (to-PA ' a 3+ (Bud) win/u 1750 Mat; no 'W 5:1. t5»:- xfimyfl 6‘1.— amd Lee, 'a W “5‘9? SA‘DMQMCI‘ a; WCL 0M V. w Awarding “Elf-H] ,. ,°, 715? «0H1. 053“ M w Kit?“ WWI:- -C?§c¢a5v~eb aim-IN Wei-M (Val 6:34ng $1? '9“ 0 W‘ H" M5 sumqu cw. Wjawwufim {Gabi ...
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