c123_2008_quiz1_key

c123_2008_quiz1_key - Wednesday 11:30 am 20 Minutes Dr....

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Unformatted text preview: Wednesday 11:30 am 20 Minutes Dr. Woodward Spring 2008 Chemistry 123 Quiz 1 Lablnst Name Two-Digit Section Number ALL WORK MUST BE SHOWN TO RECEIVE FULL CREDIT 1. Consider the equilibrium that exists between Cd(OH)2 (FW = 146.4 g/mol) and it’s dissolved ions in aqueous solution. a. [2 points] The solubility product constant, K5p = 2.5 x 10—14. What is the molar solubility of Cd(OH)2? ..i-l ’ "z. x (7. >0 : Li >43 Cé (MEL-.22 cgl’itloe' SD 2.6..io : X: L‘fixio‘b M _ 2. M3. = [of] Low 1 b. [2 points] What is the molar solubility of Cd(OH)2 in a 0.050 M Cd(NO3)2 solution? CA (QEDL q: (31* + DQHP Kg? -:. [LAD][OH_]1 1 "I O-D‘SC’ D 2,6xlflj—H = (0.056. RXBCZK.) C +>< 477* 1.“ (3,0st (4(13 E 0,050+»: 2.54 --’l st : 35 x lo #34 c. [2 points] What is the molar solubility of Cd(OH)2 in a solution that is buffered at pH = 9.00? Ks? I [C311 [midi (Sub??ch ck PH 20.00 Exes fl“?— Qj4;‘\.i\nr\‘°‘m Vim 0“: [PH] 255-: i0 H ': X (i xibps )1 = ——-=> ,Oi—l: 500 PH that) V s< : 2.5le ‘i M - S Lei-V] = \x \0' 2. A beaker contains a saturated solution of AgCl. Will addition of the following reagents increase the solubility. decrease the solubility or leave the solubility unchanged? [1 point] Concentrated NaOH solution. E‘flwq qukko-Mh‘xté 0"" \V’LLW'Qf-“L [1 point] Concentrated HCl solution. 'Dgcrmr—se... ‘ E [1 point] Concentrated HN03 solution Mahatma? A [1 point] Concentrated NaCl solution “Durach WED-.0579} [1 point] Concentrated NaCN solution “gnu—Q a my Q1—W11:3O 1 omdd kayo km gooey; ‘ swig. “swim (madam. r,’ ‘3, 3. [4 points} The formation constant, K,, for the complex ion Cu(CN)42“ is 1 x 1025. What wouid be the molar soiubility of CuBerKs]D = 5.3 x 109) in a soiution that is 0.50 M in NaCN? CokESril ($3 :5; QQ” o 963;?” K: sugxu‘fq . _ N 1,-— . g co,“ 4 him! :2 Cu Como cal-Q K \x 102‘ Oh art + 40$" 3— CACCMLP-t— gar” K: 33x10“ 1 0.50 O Q c2. #4“ K 'Z.>< %— E O‘5Q"L\>d >< 2x. Complex Ion Kf Equilibrium Equation AgmHshE 1.7 x 10" Ag"’{aq) + 2 NH3(aq) : Ag(NH3)2'!'(aq) Ag(CN)2'" '1 x 102‘ Ag‘mq) + 2CN"(aq) —-= Ag{CN)2""(aq) M6203)?“ 2.9 X 10” Ag*'<aq> + 2 5203.2“(am m Agtspshé‘wnq) CdBrfi“ 5 x 103 Cdz"'(aq) + 4 Br"'(aq) m CdBr42""(aq) Cr{OH)4“ 8 x 102" Cx-3'*"(aq) + 4 OH"(nq) : ammo—(go) Co(sCN)42* 1 x 103 Co2'*'(aq} + 4 SCN'“(oq) m Coascmfiaq) CL1(NH3)42"" 5 x 10-‘2 CuE'*'(nq) + 4, NH3(rzq} —* Cu{NH3).;2'*'(oq) Cu(CN)42” 1 x 2025 (112mm) -+- 4CNan} m Cu(_CN)42"'(aq) Ni(NI-13)(,2" 12 x 209 Niz"(aq) + (iNI-13(aq) 22:“ Ni(NH3)(,2!'{aq) Fe(CN)f-,4— 1 x 1035 Paging) + o CN—(aq) :2 Fe(CN)6'1"'(aq) Ec{CN)(,3" 1 X 1042 Fe3'5"(aq) + 6CN'"(a_q) : Fe(CN)63"(aq) QloW1i23O 2 Dr. Woodward Chemistry 123 Wednesday 2:30 pm Spring 2008 Quiz 1 20 Minutes Name Lab Inst. Two-Digit Section Number ALL WORK MUST BE SHOWN TO RECEIVE FULL CREDIT 1. Consider the equilibrium that exists between CaCOa (FW = 100.1 g/mol) and it’s dissolved ions in aqueous solution. a. [2 points] The solubility product constant, KSp = 1.8 x 10—14. How many grams of CaCO3 will dissolve in 2.00 L of solution? ‘ ._—l \ \ ‘03“ \0 mo ' ' ‘ \ out C¢C03 7:3 Cu,“ + (at ___—__ w_Z.OO L. ,L 3‘ L— \ wild}: LLBP : fl [Coir—1 1 1 1 _ . : 3,7,4 [0 M; c L5€K \O_w‘ : b0 643,1 . 3 x a. L '3 1': \QF W“) b. [2 points] What is the molar solubility of CaCOa in a 0.015 M Ca(N03)2 solution? . 4, 'L” CecC—O-J) T“: C0} + C05 M5? : (oar?)ervi \ I 0'06 O [figxtoflh‘ 2" (0.6.9.5) CK) . >< >< .- C— - . i ‘54 1'. ‘34. ‘7- M E Otoffit—M ’4 c. [2 point] Will the solubility of CaCO3 increase, decrease or remain unchanged as a solution becomes more acidic? ##P-r-Zi; a? a. 2. A sample of CrCI3 is dissolved in solution and 2 mL of the resulting solution is added to a test tube. Several drops of 6 M NaOH solution are added to the test tube leading the formation of a blue—green precipitate. Upon addition of excess NaOH solution the precipitate dissolves. a. [1 point] Write a balanced equation to represent the reaction that leads to formation of a precipitate. Q3 ¥ Cr Cac‘_\ + EOHHHCQCI.) Cr (01435 C5) b. [1 point] Write a balanced equation to represent the equilibrium that leads to dissolution of the precipitate. Cr (DH-3.3) (‘9) + OHHLcLaIs\ {"1} Cr (OH); Ql—W 2:30 1 3. If you begin with 1.0 L of a 0.075 M solution of NaCN and add 1.0 L of a 0.500 M Fe(N03)2 solution. a. [2 points} What is the concentration of CN‘ before any reaction occurs? What is the concentration of Fe2+ before any reaction occurs? «'1 _‘ _. 000,-] 5 M wl‘QL‘ __ M _:_ 0.56.300'154 Lal— ’ \.DL+" LOL. [Fe/u '5 00155 M LOL +1.61— b. {1 point} Write an equilibrium equation for the reaction that occurs between Fe2+ and ON“. F6329 + (ecu be.) a: Fe. Cm >2, keep c. [2 points] What are the concentrations of Fe2+ and ON if the reaction in part b‘were to go to compietion (no equilibrium)? C.) CH“ La, it“. we HMS mots-imam ~23“) [CM 4] e 0 C5) To CcvWKEi-QILM) mtm CF5— usL mom\& mamas; + — l we Fe“ 75 o\ r: L 1'1" 1 H' a l : 0-O\ M Q” l _ FE. gmx‘imumLA = LuL1SML\CN x (ovnc\ (34,— my O'SCOM\ -—0.0l2.“9mo\ "Wu. cm mkrcéfiovx 5’; firm. rawxcgw‘xu.3 fire/1* "L3 :9 [Fe 3 1 (1'0 L W c. [2 points} What is the CN‘ concentration after the system comes to equilibrium? : Owlq'f M Li— . _ _ J_. a ~35 \. Fe. (04):, -=_—-—~ Fault— (o-CN LL; *' K? ’ \54 W3 .23 W (I: 3 c; . _ ’i e u w I 6 wt c: 1% Kd : EECNGFJ” . fl Ll...‘ C “X +~X *(‘DV LFLLCJJ5L¢ T—fl - ' _ t: E éefimdfiix (33147 *“" (bx i (M655; Co-qutK5acmv O‘OQEE *— ‘24 K L: 1.17332th w—a [GNP] ': (0“ 1 Complex Ion Kf Equilibrium Equation I S (é‘o K it) o. o r235 Mot Ag£NH3)2“" 1.7 x 1,07 Ag'traq) + 2 Nfigwq) :2: Ag(NH3)2+(aq) 1 D C" Ag{CN}2‘ 1 x 1021 Ag"'(aq) + 2 CN'""(aq) 2 Ag(CN)2‘"(¢zq) ‘ 2x55620923“ 2.9 >< 1013 Ag+(3q) + 2320321”) : Ag(8203)23"(aq) CdBmz' 5 x 103 Cdltraq) + 4 Br rag) :2 CdBrdz' (my) Cr(OH).f 8 >< 102” Cfitrm} i» 4 OH'“{aq) :m: Cr(0t~l)4“{aq) ensemfi“ 1 x :03 C02"(aq) + 4SCN"'(nq) x Co(SCN),;2"(aq) cum-13)..“ 5 x to” CLIZ‘Etaq} +- 4 N'Hfiaq) : Cu(Nl‘i3)42':"(rrq) Cu(CN}42’ 1 x 1025 C112+(aq} + 4C‘N‘"(aq) t—* Cu{CN)42“(aq) Ni{NI~13)(,2+ 1.2 x 109 Nj.2+(rzq) + s Nittgmq) .m: Ni.(Nt-13)(3+(aq) Fewest“ 1 x 1035 Fe2'*'(aq) + 6 CN‘rnq) :2 Fe(CN)(,4"(aq) Fe(CN)63"" "l X to“2 .l‘7e3'i(tzq) + (a CN“{aq) m Fe{CN)63"{rzq) Ql—W 2:30 2 Dr. Woodward Chemistry 123 Thursday 8:30 am Spring 2008 Quiz 1 7 20 Minutes Name Lab Inst. Two-Digit Section Number ALL WORK MUST BE SHOWN TO RECEIVE FULL CREDIT 1. Consider the equilibrium that exists between Pbl2 (FW = 461.0 g/mol) and it’s dissolved ions in aqueous solution. a. [2 points] The solubility of lead (ll) iodide is 0.76 g per Liter at 25 °C. What is the value of K5“? PM. :3 P511131" gigs”: ”‘ I‘m” a: Lesiefim W _ _ 1 Lists KS? rm; 1 LI J (Jeni/B/ Q6 '2— 7.» * ; Lied“ D =l.9>~l0 b. [2 points] What is the molar solubility of Pblz in a 0.050 M Nal solution? Pblz : Pb'b‘i. 11‘ K5? " [Roll]er I 0 (3-050 Lassie“ : vwrgfii' x (OESCHZK) c. :14; 2" a x («2.05031 E - >< O-OSCHZX "x = 7.2 x 10"“ M c. [2 points] Will the solubility of Pblz increase, decrease or remain unchanged as a solution becomes more acidic? TEL a. $7 WPVOK—‘ixmokz 01A u:\\\\ Fame-2.3M L»;xC‘\(Lm.E£ A ‘ogganh o 1” 1% gen/{\uaoicz. W 05!: c1— $1FFOWAC\ GLQKA CH1) 2. A solution contains 4.0 x 10‘4 Ag+ and 1.2 x 10-3 M Pb”. If Nal is added will Agl (Ksp = 8.3 x 10'”) or Pblz (KSp = 7.9 x 10—9) precipitate first? What is the concentration of I“ needed to begin precipitation? For Md“ 5Q“— M PFlv \poog‘tw‘; when QT—Kg‘) 931 2i so; .» .1 ' veil :4 Pb“ + o1" 1+ w 2. Q: Wang] L 3Q: Sb 1'3] w "L [T] ‘ Q . ‘ L”: ([09]) ‘ <[Pbu]\ [.Psfi] _ _ Ct “501- th— -3 L _] <6 3 “jun ‘3 [.1 12<:"1*\On3> : Zip-JD 1 = '___—-———-'X _z.l..o* ’* Q1-R8230 14.0 .4 ion“‘ ’ ‘ 4.51 C R931 [2in ir‘xrsjimoms LI'] =2.\k\D Cu) :2 \%Q,7 ’mo\ / 3. [4 points] What is the concentration of free Ni”, if 2.25 g of Ni(N03)2 is dissolved in 1.00 L of 1.2 M NH3 soiution? A 1,4- - 2 r . - 1+ q Nu L (OHHB r” NuLNHeDG 14F: L’Lxxo _§AK:E_LL Pfiflwma m ranLLima SSE/‘3 +0 LOWLPLTk—‘Uw ’ I R in f?” .. . L H - . 2:15 mimogl x \W\ mans-91$ x \m‘ “ 3 i- —, Mada“ c3 F5331 5 moles): \ WA .4; was}; \ wfl H u . ‘ 1+ boot. NH?) Sat/x x L-1 wok NH}, x \ "‘0‘ M‘Q‘Mg‘o i : Col ma‘ 1 L to WA NHB ‘M Baa-Wye, N11040:); Proimtfimfi LL55 froth“ Hf x”) m hwbd'j‘fi ("9.0.9'5‘m Ww , m, m (wan is QWtflfi-fQ hue» ¢cvucm¥m3fi mix-6 aft“ \o—é— Cu.“ 1 a (-3 (“Mllfinfis rm’rwvxifi 4 J1 ~Z '_‘. tul’sk mD\ : M w 1 m Wt - wmxdzwm : W3 ”‘ 5 c. ff“ 1.00 L Z by? (L divsocjdfim G—‘tJ’ULLf‘tuM/k ran i 7—) “340 2+ .v, NH m r”: a“ mmgc’ 3:“ m + (a 5 a m 1.. i ‘5 C: j: Debi?” 3 b I [H‘L‘ZAJ + 34 'k C054 [/H’i "F C . ~-~ K _ .,_._ W—— X LVB’VQJX L, E ®~@"7—3’“>< 3.“’5x\o"‘° ,; >< CUB *Lm) ‘ ‘CJ'LE—K Complex Ion Kf Equilibrium. Equation (0 3 Ag(NE--I3)f‘ 1.7 x 107 Ag+(aq) +~ 2 NI-{3(aq) x Ag(NH3)2+(aq) REDWM Ag(CN)2" 1 >< 1021 Agfiaq) + 2 CN“(aq) : Ag(CN}2"‘(nq) x 44 00ml?) Ag{5203)23m 2.9 x 1013 Agwaq) + 23203215257) : Ag{8203)23”{aq) CdBmz“ 5 >< 1:03 Cd_2"'(aq) + 4 Bram) 2 CdBr42"(aq) c.1- OHh" s x 1029' (33%;: ) + 4 OH”(aq) m Cr(OH)4'”{aq) . wt?— ( L; F q a Co(SCN)42"" 1 x 103 _ C02""(aq} + 4SCN"“(aq) 2 Co(SCN)42"“{aq) X r Ll” >4 K: Cu(NH3)4"-+ 5 x 1012 ' Cu2+(aq) + 4NI-13(aq) :2 Cu(NH3)42+(aq) fig.— Cu(CN)42” : x 1025 C212"'(nq) + 4 CN'"(aq) x2: Cu(CN)42"(aq) N1(NH3)62+- 1.2 X 10" Nihmq) + 6 NHgmq) :22: Ni£NH3)(,3""(aq) Fe(CN)64" 1 >< 1035 Fe2';'(azq) + 6CN' (my) F0{CN)54"(nq) Fe(CN)b3” 1 x 1042 Fefiaq) + 6 CN"“(aq) :2 Fe(<:_N)6-“”(aq} Ql-R 8:30 2 ...
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c123_2008_quiz1_key - Wednesday 11:30 am 20 Minutes Dr....

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