PS8_Sol - Chem 215 Fall 200 Problem Set 8 Due Friday Oct 26...

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Unformatted text preview: Chem 215, Fall 200'? Problem Set 8 Due Friday, Oct 26, 2:00 PM Suggested Additional Problems: Ch Il:23,25,27,29,3l,45,51,6l,7l Name: Lab TA Name: Lab TimefRoorn: I. In the space below, sketch the galvanic cells incorporating the following reagents. If necessary, use Pt electrode(s). Show the direction of electron flow, the direction of ion migration through a KNO; (aq) salt bridge, and label the cathode and anode. Write the overall balanced reaction. Finally, shew the standard line notation (cell diagram). You may assume that all concentrations are 1.0 M and all partial pressures of gases are 1.0 atm. You can use the tabulated reduction potentials from your text. a) Cu2+(aq), Agttaq), Cu(s), Ag(s) Cuzfilg .7 Cum E“; +0.3‘l01/ a. gang _., A“, E - +0.9oova find- AMDL " CUQ’] *3 CULJ‘TZ 0/ All (aM'--l-[Aq+* E, ‘5 Aq (5)] CLGH 214er “a Cog; « Afifil + Cvtsilcféa ll “‘1 If3"”! (51 Mao; +39?th ,., Mgt’WLlWLO e ”157v bwflmm)’anwaqLF-(aqLFfig) F as a “I F" (2":- +2 m v *IfudNé - L e i—v ‘ - _. ' .. i -a (nude. ([email protected]+ Sfiiu H14 09:.ng Pt / 1+- 5"; t " +3HLO 1+ 3 a, we we 2%» t {i HEM” ‘1 Chem 215, Fall 200'? Problem Set 8 Due Friday, Oct 26, 2:00 PM 2. Referring to tables of reduction potentials in your text, answer the following. Briefly justify your answer. a) Is H+(aq) capable of oxidizing Mg(s)? ZH-‘d'ZE-J’HLH} E“:- 000 ¥F(.a+- y MQL++Zg4M§{J) Enz-‘ZJJ‘C 65 b) Is Fe3 (aq) capable of oxidizing Ol-l' (aq) to produce 02(g)? 0163144 ”20(2) “We A q 03" 5° =+ a 9 cm/ FGSfi- 6—9136?- 3,) E°=0.'17H/""5-M_-—- Vii—S— c) 15 l-lz(g) capable of reducing Sn2 (aq)? —0. 2H+ +243:'-I, 3‘".ch a 00 ‘y' S— g/L’+- Mo £7 “id/Zea ‘9 [an] E *‘b’W/ *" d) 15 Fe2 égaq) c/pable of reducing Cr107 (aq) to 0'3 (aq)? +6 -5 Fe; E"-=0 77:1; cifofiw Nance E3426» 4.7”;0 Ethel-33"“! Jim-rt- $2.9 o) Is Fe2+(aq) capable of reducing Cr 2+(aq) to Cr(s)? F831}. g #7 Fart E”: 0.11: L" A9" True} Crz+ra€~1 Crm 5": ‘030" 3. Calculate the standard cell potential E°ceu for the following reaction using standard Gibbs free energies of formation from your text. Note that one of the half reactions is H100) + CH30H(I) —> CO; (g) + 6H+ (aq) + 6e'. CH30H (l) + 3f2 02 (g) —* C02 (3) + 2H10 (l) 590‘ “’1 (“Ml *ZMOrl “M03" AG}- (“,0th "g Mirfozml : flown}? (lmre)7‘(‘237fig_){2mfl) —(«mflj{m) —-§‘f’0) “‘ - ”)0; a? WHalrremvi‘ion '15: OZ +Ll'l'l++qef 432.4420 Mumflglma '33 4“ b*l-¢i¢¢lmm 2.; 01 +- QH‘i-réé" ——) 3sz 0 Thus neg cw“— 'nFEO __.—- E0.— — AA: “702 0004 TF (Wm/m) LZIV m0 |l Chem 215, Fall 2007 Problem Set 8 Due Friday, Oct 26, 2:00 PM 4. An electrochemical cell consists of a standard hydrogen electrode and a silver metal electrode. a) What is the potential of the cell at 25°C if the silver electrode is placed in a solution in which [Ag+]=l.2x10'4M? &(Aj;firé' -—’: Helm) fizzlroot/ How—t 2W+ zé' -E° = 0-00 + C‘__ . - = . 2Aq+ryzf4giflam~rlfiéiv€w~ 090 0 090v g=g°-——":‘””"jz7¢?L~ 030* T ”flower = 0.300—0.23?£-‘O- $7981" bl ”the silver electrode is placed in a solution ofOJO M NaBr that is samrated with AgBr, what as the cell potential at 25‘1"? The liq. for 5.0 x ”I” for AgBr. “ ~L3 fir 8/“ a?“ IQ ++ gr (”rs-f; ”Sax/0 -4} 3 C57 5 ? 0.1011 5*: ——-—--{£f£o =' Sox/O'JLM. = 0-800 —-5.(,(,<j EON/D'd" ( J : otsw" c} The silver electrode is placed in a solution of unknown [Agf]. The measured potential at 25°C is 0.6]0 V. What is [Ag‘] '.’ a I (E— : E o a 6—21" 0 é? L I’— 7 59;? 0.00 : 0.900 - (0.939 1),” 5%).” 9 PAL. :.~ —- ./9O _ “5549f d—(ijsqj * “LCD-LN? [As-r3“: /¢’)‘ “"1"? 2 3.3!)!!an =) [At-43:“ (,J7xi'0fl‘f/‘7 (ii If you wished to construCt a calibration curve to determine how the cell potential varies with [Ag']. what would you plot in order to yield a straight iine'? What would be the slope? __ c_ .0572. .—-L_ g —E OZ [9'7 [’45th E350 + (”fifty—"#7547771 2 : 5° + cowl/0754f} Plo‘F E V5 103 [Afr] soft m be, 5—?lml/ Chem 215, Fall 2007 Problem Set 8 Due Friday, Oct 26, 2:00 PM 5. Consider the electrochemical cell, operating under acidic conditions, formed by connecting the following half cells: A13+(aq) + 3e‘ —~> AI (5) E0 = 4.706 v Mn04'(aq) + 8H+(aq) + 5 e‘ —) Mn2+(aq)+ 4 H200) E10 = 1.491 V Note: The second cell utilizes 3. Pt electrode. Pf a) At which electrode will reduction occur spontaneously? __ 11] Which electrode is the anode? __ __Iq / ct Write the balanced cell reaction for the above galvanic cell. 1‘ / —' 4 _ r- L7- (,2 ‘fly + 5‘4 3 EMAWNfiA‘LQQe gmflmq‘rw’a J 3 ”01a” ”to a; ”31» SK 4 It” _., A! («H go) _; 3mg“; an?” rm d: Assuming that the concentrations ol‘ttll species in solution are 1.0 M and the temperature is ZSUC. what is the measured cell potential (E‘Lcu) in volts? 0' 5%? = mor— (—naw) : 3/97V' e} The above cell is operated for a period of (a. fill hours. producing an avers e current of 0.750 Amp ‘ t t "—t’zeoo—r 1 (our : 23..er- i) What is the change in maSs oi the aluminum electro'fl'e to grants? AI = 26.98 g/mcl. (litany. i’ronr‘Lr-"J: (0-75-13 c/I) (2 3r (/00!) =- 0,552“: . are let é— : ‘VU‘YSLC = 0-f32r Mr? =2 mafi) 14f:- O‘QL:Q.OLOL flmczm [email protected]£1C)£ZC.9£fi)-§ 2.933, ii) Assume that 500.0 ml of 1.00 M Al“ solution was Initially present and that t e volume of solution remained constant. What is the final concentration of A134"? lack H Mel O_§00mm{l! a? A i“ LU: outline 0-OLOLmrEaS: ul: Al malci my" a'l‘ (Mi: 0- SLOL [My AM = W2 [‘1 Cttlculatc the cell potential (En-u) ifthe cell is operated with the following concentrations: [nth] = 0.05 M [Mn3” =1.3o M [Ml-[04'] : 025 R4 .- o_;‘9" ‘ pH = 0.50 =) [1430*] = l0 — 0.31m Edgy: gauge ‘ 0'05?2- KO? 6 = [ 4203M? _ gnfta-OS); : 7/,7 62 W]‘* _(a.25)3/03’9w W M 6&2 3/?l/ — Qf—Sié/ay/er/a‘) '—’— 3l£ l/ ...
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