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Exam1sol - CHEMISTRY 204 Name Hour Exam l February 179 2010...

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Unformatted text preview: CHEMISTRY 204 Name Hour Exam l February 179 2010 Signature Prof. Jim Lisy This exam contains 30 questions of equal value on 9 numbered pages. Check now to make sure you have a complete exam. You have two hours to complete the exam. Determine the best answer to each question and circle your answer on the exam. Total (100 pts) Useful information, formulae, constants and a periodic chart of the elements is on the last page of the exam. You can remove it from the exam as you answer the questions° MERSION A CliEMiSTRY 204 Spring 2010 Hour Exam 1 Page No. l 1. On a phase diagram, What is the name of the point Where the liquid~gas phase boundary intersect with P :- 1 atm? Triple point Critical point l i M}, lsgi‘fi l Normal melting point Normal boiling point Sublimation point seesaw 2., The normal boiling point of ethanol is 78.400 When a nonvolatile solute was dissolved in ethanol? the vapor pressure of the solution at that temperature was ’740. Torr. What is the mole fraction of the solute? (1 atm :: 760 Torr). a. 0.974 b. 0.803 e. 0.0263 d. 000170 e. 0.197 3. Which ofithe following conditions makes dissolution the most favorable? wk a. 32M geld? .2 if 0 iv \ EA» “W ’l’ A itfltfi} R50 llgée: 55M? will? (“i5 Ell‘flh‘lk will} 51%.‘l‘riee-ti‘a/wsol maul skill fig’uflé.»f at vs High lattice energy and low intermolecular interaction with the solvent. gm“ Q. gag m it» its, r, 5; an Low lattice energy and low intermolecular interaction with solvent. “y p: M, fliwm 5 High lattice energy and high intermolecular interaction with solvent. Low lattice energy and high intermolecular interaction with solvent. None of the above. 50%;“??? 4-. A solution prepared by adding 0.50 g of a polymer to a 0.200 L of toluene (methylbenzenea a common solvent) showed an osmotic pressure of 0.582 Torr at 20.0 0C. What is the molar mass of the polymer ? ital § tween/me {xv-M “:wa UM a4.m,..i\w,_..m,7 > {(3 ll '- S (if, \ 5.4 x103 g/mol. it, (I it i » V to e a. b. 8.0 x 106 g/mol. c. 7.8 x M4 g/mola d. 2.3 x 102 g/mol. e. 1.0 X 102 g/mol CHEMISTRY 204L Spring 20l0 Hour Exam :1 Page No. 2 5. Below is a simplified phase diagram of C02 (source: http://scifunchem.wiscoedu/y H] 000 1111111 VVVVVVV 11311 0311111111 51? 11:1 9 . 3 U] U] 11 11.111 11.11111 "1110 4120 100 ~80 ~81] ~40 ”’20 E] 20 40 BE] 80 100 Temperature 1°C]: Complete the following statement: C02 has a normal sublimation temperature of the minimum pressure and temperature required for liquid C02 to exist are “800C9 3atm/N6OOC1 111101 11 1'? 1.1K“ Vi. i1 312V {"2 6% ‘1 11:12; 11; (‘3 112 ((1 180°C, 50 atm/400C" f1 121 111V :11 4O°C1 3 atm/2600C " " 40°C1 50 atm/4000 none of the above. 9949.0“? 6. Two ideal solutions have been prepared. Solution 1, which contains three volatile compounds A B, and C has a total vapor pressuie 0.602 atm The vapor pressure ofpure A and B at 25: C are 0 6V:/6 and 0. 93Z atm respectively; the mole fraction ofC in this solution is 0.260 ‘2’ 11111271 1 “11111 1211 s 21 :2: (.1 11:11:: 1%: 1111 110:1 1, ~11 1.11:1 11111 1’ 1.5.1 111-111 5211251 "1? 221-»,- \1 Solution 29 which contains volatile compounds C and D, has a total vapor pressure of 0.437 atm, ) The vapor pressure of pure D at 25°C is 0.725 atm and the mole fraction of C in this solution is 0.60. What is the mole fraction of B in Solution 1? 11 1:12 W 2 0.146, (if 0.217° V1111 V V (1.245 *1»? (31362 C? (1&12 1 111,62 2 12111111 {1121121 1 1 119-9912 0300. V VVVVVVVVV VVVV V insufficient information is provided. 113 [52“ 3/121 2211:: , 1 M W C31 ‘ ' 2W1: l1 1’ 1‘1 _ _ VV 111.1111 211.1111 11VVV VVVVVVVVV VVVVVV :A‘ jigé (6“;0”WCQ\}GQ7C1 1111211 {112’} 1’ 1.1113121011211212121111 1;: 1352141 CHEMISTRY 204 Spring 2010 Hour Exam 1 Page No. 3 ’7. The change in Gibbs free energy for the conversion of graphite to diamond (god) at 298 K, t5 MK”; A \2 K 3'3 f’K’l K" song—sen :: 3.0 11/111101. At pressures above 1 4 x 104 bar this reaction becomes spontaneous at 298 K Determine the change 1nmola1 volume AVm(g_2d) for this pr.ocess Assume that the molar volumes of : diamond and graphite a1e constant over this p1essure1ange t :31: :E at; @722 3, gm (WK? , . a) Insufficient information is provided b) 2.12 01113 c) 2.14 11104631113 {2 . 11) “2. 12 x 1113““ m3 Wit e) 2 12 X lQ'3 m3 ass .1, he, {’1 212 .. 25v ta 2155 K? _ 4551», 41:62‘ : K39; t/t'éefl £3,661 EARS , 1.1 8. The fieezmg point oft butanol 1s 25 50 oC and kf 1s 9 l K kg/mol t butanol abso1bs wate1 on exposure to air. If a 10 g sample oft butanol freezes at 24.59 0C, how many grams ofwater a1e present in the sample? (MM (t~butanol) = 74 g/mol. MM (H20) = 18 g/mol). al 1161118 g A1 :1 KM E: E.» . b) 0.18 g M 131 Q: 5:: ‘1: c) 1.80 g . e) 0.56 g 9. Considering that the enthalpy of solution is positive which of the following is/are true? KEEEZK‘K EtE LEM“? EEKME” (E EE> E a t,»-KK"Elhe process is endothermic. b The lattice enthalpy is smaller than the enthalpy of hydration. c. V‘EThe enthalpy of hydration is smaller than the lattice enthalpy. 51 e Both a and b. Both a and c. 10. Calculate the molality of a 65% (by mass) 1412804 solutiona if the density of the aqueous solution is 1.55 g/mL. w , {#115} GEE it flies: /EKg§” Ks Q 1:113 amt. {118:2 2/12 W W122 KKK” a. 10.3 mol/kg lo, 18.9 moi/kg c. 6.63 mol/kg d. 5.49 mol/kg e. 55.5 mol/kg. 1 s1 v»: CHEMISTRY 204 Spring 20] 0 Hour Exam 1 Page No. 4 l 1. Calculate the molar mass ofa molecular solute if the freezing point changes by 20°C when 5 g is added to 200g of water. The freezing point constant of water is 1.86 K kg molEE. 26:1“; hat; EEK: Eéii/Etel E E EEE a. 23025 git/moi ‘ b. 232.5 g/mol c. 465.0 g/mol d. 46.5 g/mol e. 11.62 g/mol t to??? l2. A water permeable balloon filled with a salt solution is placed in a bath of pure water. Which of the following statements is true? 3 ; 3 The balloon will shrink of 62 El- \ W ~' El :3; 3%» s": Ex; m at 71/1/57 The balloon will stay the same size E ,. é 5. 'l‘he balloon will expand E “9E EEE E EEEE‘VEE E3 EE 5 EE E‘E EEE The balloon will float in the air Etizsm Eti a} < (:15: EE {Wig/gm 59/5 4 None of the above “ not??? 13. What is the van’t Hoff factor of an new substance (MM = 137.00 g/mol), if a 20% by mass solution of the substance in water caused an increase in the boiling point of 0.47 0C. The boiling point constant for water is 0.51 K kg molE. a. 0.3 is) mm; ha 05 o. 1.0 d. 15 e. 2.0 .3 3 it!“ ”éeq ; v Egg asst is to i 14. A sample of N204(g) is placed in an empty cylinder at 25 0C“ After equilibrium is reached; the total pressure is 1.5 atm; and 16% (by moles) of the original N204(g) has dissociated to N02(g). Calculate the value of KP for this reaction. a 6.49 of da $73? b 2.65 if ’ E liE ” EE E {E I; a 2* ' c 0.380 s :5 E egg; ‘5’“ ”E :2 c) x it ; d case 3} {2 wt ”E c 0.126 t “E: ”E , i; E owl-1a. 3 3 x E? \ ”3"? ENE a E“ Eta/w» ‘7) I: igmwwf “7’ E. 3/ EE t" , er ” ' . QR § Q9, Q _ éEl“vAj\ , 4"” Elsi ,/) ‘ a «v {j E if he” E {in WEEE E EKEEEQE ”E M M”) 3,.) : I ”’7 EE WW it; We” Ei (31411314181111 204 Spring 2010 Hour Exam 1 Page No. 5 1 3 A Solution 1s made by adding 50 mL 010 200 M acetic acid to 50 0 mL 611.0 x 10"3 M 11131. .12 Calculate the p11 of the solution 11153.1: 151 11 1511:! £1 (11511! 11.1 1; 1 a) 2.40 b) 2.61 c) 2.65 ; d} 2179 11 2-95 1 , 1 ........ .11 21f, M11”? 1531:. 1 ‘11 16. l Cons1de1 the following equilihiia involving 802 (g) and the11 couesponding, equilibrium constants f 1 801(1) 1 5101(1) 1—1 801(1) K1 ZSOJQ<1ZSOJw+OJQ 1% Which of the fellowing expressions relates K1 to K2? a) K2 2 K12w1., ...... , {I U . . b) 1;f=4§1 111'15 , . 1,1 ,1 111 ’ 5;”11 0) K _- :K1 ,1 51 31 1f). :2 1, {“75“ 3 ”75“”1r’. ‘ E) 31;"1”§121111 “ 11 1’7. ’ A mixture of 803, 021 and SO 3 at 1000K contains the gases at the following concentrations; [802]: 5 0 x 10""3 M [02] — 1.9 X 103 M and [803]: 6.9 x 103 M What 1s value of the reaction quotient? [email protected]»+oz112soxg K:2m a) 145263 1; 1 b) 1001 1‘ c) 5 a) 726 e) 279 18. Boric acid and glycerin form a complex B(OH)3(aq) + glycerin( aq) e1 B(OPI)3~ glycerin( aq) with an equilibrium constant KC; 0. 90. If the concentration of boric acid IS 0.10 M how much glyceiin should be added, per liter so that 60.0% of the boric acid is in the form of the complex? .20 1'7 M 1 111:} { :3 1/3 X i 6) 1.111 g 5% / c) 3.2 M . 1 d) 2.3 M -15 11:”. Ly~é5iw a 28M: , 111 1< 111 {"5 J .. 1:7“ '1 élf ‘ 1 ;1 *1 «21; 1111/" 1% $5215? CHEMlSTKY 204 Spring ZOlO Hour Exam l Page Not 6 19. Carbon tetrachloride can be produced by the following reaction: C82(g) t 3 C1261) 1—>~ 320%") t (304(8) Suppose 1.2 mol of CS2 and 3. 6 mol of C12 were placed in a l 6 L flask. Afte1 equilibrium has ,. ‘11? been achieved the mixture contains 0 90 mol CCL; Calculate K 5" ‘ a) 59 i t 1 ( f b) 16.9 74" 111' . 1;: c) 0.4 , {W5 k) A 1: d) 29'} * r {c M {Tl-{i l is Z1151 5 1 i} <21 - «1 20. If the following 1eaction is at equilibrium what would cause the reaction to shift toward the reactants 21113119 9 H2(g) + BI‘2(s) a) increase in pressure of an additional gas such as N2. b) decrease in the pressure of Em C) increase the pressure of HBr 01) decrease the pressure of H2 {"153} increase in presSure oi'H2 ' 2l. If K2 the equilibrium constant increases proportionally with temperature for a reaction, that reaction is , ‘ ' /,,- _. f‘i {5:34. 1151,17} 3”; if}; a) exothermic b) endothermic c) at equilibrium d) mesothermic e) spontaneous 221 The equilibrium constant is KC = 0.56 for the following reaction at 250 0C1 C1361) 1' C1 (5:) <~> P€C1§(g) 1'21 .1 , “N If there are 1.2 moles of C12 and 4 1 moles of PC15 present in a 1L Cylinder at equilibrium what is the concentration of PC13? t 1 _ 1 x m , "l ; a) 2.9 M {53 3:: (if? ”3171:? £7151. @1111 b) 601 M c) 10.4 M d) 19.7 M e) 29.0 M CHEMISTRY 204 Spring 2010 Hour Exam 7, Page No. 7 23 A teaction has an equilibiium constant of 5 76E4 at 100 0C and a change in enthalpy of 11 4.15 k] What is the change In entlopy? 7 s7 "1 1 7“). i” , 7‘ 2’5, a) 3137K 77 “ 7)) 130m, c) 74 J/K. \ ” a) 80 7777 e) 65 77K 24. Lead oxide reacts with both acids and bases in the following ways: PbO ~7~ ZHCI __> Pbe +7120 PhD 7 Ca(OH)2 +1720 4 Ca2+[Pb(OH)4]2“ Knowing thisa we can say that lead oxide is: a) Amphibious , b) Amphiprotic 7111? ,7 , 7 777:; 77 e) Amphoteric " 7 (1) Both a) and b) e) None of the above 25. At 0°C, the auto~ionization constant of water, Kw, is 1.2 X 10775. What is the pH of pure water at 0°C? a) 6.58 77, 7., 7 77 ,7 7 b) 6.88 7 "7° 7 c) 7.00 77 71 7 a7 ”7876 7’ e) 756 26. Which of the following aie conjugate acid base pans? ._ 7 L H7003, 71003 777 77 m ' " 71. 1773770791704 7’7 , ' N777: NH3 7 a 7 71V cngcoox (3713710017 a) 7 H and III ,___,,,,, 7 7)) 7,11; and IV ic) iand 1V (1) H and IV (:3) IV only CHEMlSTRY 204 Spring 20l0 l—lour Exam l Page No. 8 27.Place the following acids in order of increasing acid strength: “E NEEHEQEE:+, pKE .._. 9.03 E EE‘ Jr 7? ‘ . FeEHzOEE FE pKE 2': 10.1 3“ hi 6 (EH FE ”F l E F E f ' " CE§(E‘§20)6Z+EpKa=7.49 Eg. E '* a) NMHEOW <13 611(H20)62+<C (312m2+ E3} EE‘EEnEoEE: <NiEl—lzfl)62+<CuEH2®)ng C) hangok2+ <Cu(1~120)62* <1\11(1~120)E2+ d) N1(H20)62* <Cu(H20)6 <36 (HE-0%” (:3) Cu(HzO)6F’+ < Ni(ll120)62+ < 136(Hzo)62+ 28. What is the pH ofa 0.75 M solution ofNaF? (Ka for HF : 3.5 X 104) a) 8.67 E E EE Efg: E;.l. EE‘ “E "2 5‘71 FEE: b) 7.00 ‘F‘ EFF F} 6) 12.21 E d) 1.79 F - EE. E) 5.33 EE: 8'7" 29. What is the pH of a 5 0 M solution 01 aniline (C6H5NH2; Kb _. 3. 8 x lQ 10)? /’ (if EEj; I‘ Em? ,. fl 2? E15; Ell; E E {i3 E6 E 1 $3“ ‘ , E z ‘4' w x; E) 4.36 E ,, bl 9.64 9E; 53 1 C) 0.070 . d) 9.30 e) 8.77 K} {F , . 30. A 0. 2 M solution of sodium ohloxohenzoa‘te (NaC7H4CiOZ) has a pH of 8. 65 Calculate the pH of a 0.2 M solution of chloiobenzoie acid (C7llgClOz). . , ,_ _-"E E‘ a ’ l\ ”E Fail”.- (Fl 2:74sz ii in F FF“ FF a) 2.00 Eff-IE}? Ei’? E‘? 36) 2.33 E c) 3.00 , _ _, ,, d.) 3.35 ,_ e) 5.35 EE: ...
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