Practice Exam 3 (Laude)

Practice Exam 3 (Laude) - Quiz: CH301 Practice Exam 3 F2111...

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Unformatted text preview: Quiz: CH301 Practice Exam 3 F2111 2009 Page 1 of 11 01 Practice Exam 3 Fall 2009 1. Which of these compounds is capable of forming perfect crystais at “i” = OK? SF6 CC34 02 NH3 8H3 GA. SF6 cm 02 I 0 mew/limian (329 $525 963 L4 if; one of them - “4:. .____ Wmh @“LW‘ ‘ “AM D. All offthhe (ire. NH3 2. If an isoEated system contained +5 id of energy, after 100 years AZ: CA. The answer is impossible to determine .3. Callate the standard enthalpy of formation of C02(g) from the following data: 2142(9) e W AH" = + 52.3 k3 . W+HZ(9)~+C6 AH°m——137.0kJ ' ‘ 2W+70 (g) + @200) AH” = m 3119.4 kJ 2H2(g) 2H20(|) AH° = - 571.6 k) Give your answer in k3, inciuding sign, to 4 significant figures. . a . ___________ . 4. Of the foliowing, which is not a state function? e \l T SE an we OD.H I w ‘3' R0 (35.5 f 5. For most reactions, the value of AU is very close to that for AH. True or faise? Coaster“ \i, Alia—"t Coiislméy i), All “4% t e combustion of one mole of octane, C8H18(l), in a bomb calorimeter released 5460 k3 of heat at 298 K. The products of the reaction are carbon dioxide and iiquid water. What is the change in internal energy for this reaction? 0A. +5471 kJomoi"1 q’: W1 C 03,,— 460mkgamoi“1 ~..,_,© c. —5471 kmm l t. :W 6. httpflange}.bprub.com/section/content/default.asp?WCprgDispiay‘MaSFQuizé’cWCEWa... 11/30/2009 g/b Quiz: CH301 Practice Exam 3 Fail 2009 Page 2 of 11 C} D. 45449 itiomoi‘3 @E. +5460 kJEimol"1 3?. Calcuiate the change in entropy of a large pail of water after 200 3 of energy is reversibiy transferred to the water at 20°C. —o.7333pi<“1 M A agumhfim~mwz - $0.683 kawji‘i 53.; '1’: ‘ 3% 0c. —O.683 353W 6):). +0333 351161 CD‘- E. W200 JoK“1 8. Caiculate the standard entropy of vaporization of ethanol at its boiling point, 352 K. The standard moiar enthalpy of vaporization of ethanol at its boiiing point is 40.5 idliimoi‘l. 0 a Utes M 352053) Oo.+5133oi<'1omoi"1 MUQQ 5 Ag; @E. —115 J K"1eimoi"1 T . «405' " Lanai f} 9. What is the range of temperatures at which the following reaction is spontaneous? 2H25{g) + 802(9) w 35(5) + 2H20(%) ' Il’lOfl “Weep-a it). On the basis of the structures of each of the following molecules, predict which wouid be most Iikeiy to have a significant residuaE entropy in its crystal forms at T w 0: 11. A 26.0 9 sample of solid CN adopts a disordered arrangement in its crystalform, what would its entropy be at T = 0? Give your answer in J - K‘1 to 2 significant figures. httpWangel.bprub.com/section/content/default.asp?WCI=pgDisplay%5FQuiz&WCEmta... 1 1/30/2009 Quiz: CH3OE Practice Exam 3 Fall 2009 - Page 3 of 11 12. Determine if ethylene, C2H4(g), is stable with respect to decomposition into its elements under standard conditions at 25°C. . AHF" (kl/moi) Sm° (J/ K ' moi) +5226 ,AJA H“ aim-,gyr-w-nbm C} B. fistable. 13. Which of the following reactions is spontaneous and becomes more favorable as the temperature increases? ©A.AH>OandAS>O OB.AH>0andA5<o 63c. AH < o and as.< 0 Wm- CZIF. Aand D (3G. Band C @H.Cand D 14. Iodine sublimes at room temperature. The reaction free energy, enthalpy, and entropy for this reaction, resgggiyelbmgfe W- eMW“ «may» w M- . “A amwu.msmymw.mmmmmmrmqm negative, pOSitlve, and posrtive “f B. zero, posravarae if} c. zero, positive, and negative (3-D. negative, negative, and positive OE. negative, positive, and negative Z have the largest caiculated vaiue of the residual entropy? 15 gig“! C H Cl 5 chlo obenzene QEQA. 5 5 r ) ! m '- . - O D. FCI03(3) Q E_ (304(5) 16. Calculate the standard entropy of condensation of chioroforrn at its boiling point, 335 K. The standard molar enthalpy of vaporization of chloroform at its boiiing point is 31.4 kmmoi‘l. GA. —31.3 k3DK"1:]mol“1 http:flangel.bprub.com/section/content/default.asp?WCI=pgDispiay%5FQuizSaWCEmta... 1 1/30/2009 Quiz: CH30i Practice Exam 3 Fall 2009 Page 4 of 11 OE. +506 Jam—1mm” 17. Which gégfigggggflggfiacfions has the smallest value of AS“? “ ‘‘‘‘ .6 Elfin (g) + HCl(g) —~.~ NH4CT"(“’S‘T%V~-.‘ Q 3, 282:6)” 623‘)“ :6? N2(9) “l” 3H2(g) W 2NH3(9) D. K(S) + 02(9) “* K02(5) <35. BaCIZUZHZOm m» eac:2{s) + 2H20(g) 18. Which of the following is always true for a spontaneous process at constant temperature? OA- AS'tsystem + Assurroundings = q/T O 3. AS > o . surroundings “ex ET HE? qr?” m 19= The entropy of fusion of water is +22.0 JLJK_1 mol” and the enthalpy of fusion of water is +6.01 Mandel” at 0°C. At 0°C, 65mm! for the melting of lce is in ""1 _1 t- JEK J ' I. lie [3le w QC. —22.0 JoK‘lomorl. O D. +6010JE3K'1Dm0I‘1. GE. +220 JoK"1omol'1. 20. Calculate AGr" for the decomposition of mercuryfli) oxide at 298 K. 2HgO(s) ~> 2Hg(l) + 02(9) AHf°, kJomorl M9083 smO, JEK"1Bmol”1 70.29 76.02 206.14 0A. —117.1 kmmol‘l C} B. +2462 kJUmol”1 k3 mo!“1 1‘ a; w Nat—4., “233;; “15" ’“' 3““ MM 131-26192“ :QWQ; +1111 kmmol‘ “:2 (DE. w246.2 kaomor‘l http://angei.bprub.com/soction/content/default.asp?WCI=pgDispiay%5FQuizé‘c‘WCEflta... 11/30/2009 Quiz: CH301 Practice Exam 3 Pal} 2009 ' Page 5 of I} 21. Consider the foilowing compounds and their standard free energies of formation: 3 Caflzafli CH3 03(1) mm (1) H2 02 (I) 052 (1) cycloheaane methanol hydrazine hydrogen g2: eroxide carbon disulfide +6.4 kJ-moi‘l “166 M-mofl +149 EIJ'mol'l —12{} Limo?1 +653 M-mol‘l 0c. 1, 3, and 5 00.1 E)3 22. When Dr. Laude explodes a hydrogen balloon in class, the reaction that occurs is a formation reaction. m 23. The number of degrees of freedom and totaE kinetic energy in CHCl3 are (3A. 15, 15kT GD. 5, 15 kT {*3 a. 15, CRT 24. How much heat is required to vaporize 50.0 g of water if the initial temperature of the water is 230°C and the water is heated to its boiling point, where it is converted to steam? The specific heat capacity of water is 4.18 JD("C)"3*E]<_:J"”1 and the standard enthaipy of vaporization of water at its boiling point is 40.? wnmoi‘l. GA. 169 kJ 25. Use the bond enthaépies given in the tabie below to estimate the reaction enthalpy for burning 1 mol of Butane: C4Hgg(g) + (13/2) 02(9) —‘> 4C02 + 5H20(g) Bond Mean bond enthatpy (k3 - mot”) http://angel.bprub.com/section/content/default.asp?WCIr-pgDispIay%5FQuizé’cWCEmta... 1 1/30/2009 Quiz: CH301 Practice Exam 3 Fail 2009 Page 6 of 11 Give your answer in k3 ’ moi" 1, including sign, to 4 significant figures. 26. Methane undergoes an exothermic reaction with gaseous Chlorine to form Chloroform: CH4(g) + 3Cl2(g) —> CHCi3(g) + 3HC¥(g) AH° 2“ —277 kJ Use the bond enthaipies given in the table below to calculate the mean C—Cl bond enthalpy of Chloroform. Give your answer in k] - moi” 1, including sign, to 3 significant figures. Mean bond enthalpy {k3 - molwl) 27. A bomb explodes with 400 k3 of energy released. The overall number of moles of gas increases by 2 at 1000K. What is the amount of heat released to the surroundings? GA. 400 id 63 s. 395 kJ 28. 1000 J of heat is dumped into several different materials. Which of these is most likeéy to burn you if you touch it? The heat capacity of water is 4.18 J/goC and Cu is 0.34 J/goC. GA. 100 grams of Cu g; @C. 1 gram of Cu (:3 D. 1 gram of water 29. Which of these reasons does not explain why internal energy and enthalpy values often used interchangeably? GA. The calcuEated values for internai energy and enthalpy changes often differ very little. . sat-mee?».smzmmaesmsemww “may. i L. . at“ k. 'M“ 4r.” .. (D B. The ch WWW finge in enthalpy is a measure of heat at constant p - y- W in .. u v-r -. "15M... W? - Warr- , mmgmmmee‘tvdwaame ‘ Wgfin‘nfi‘talorimeter the PV work is Dan” in ernai energy and enthalpy changes are equat O :3. Both terms provide a measure of heat of a reaction. C) E. Many reactions do not involve gases. 30. Catculate ASuniverse for the condensation of heavy water (020) at 95 °C if the S°m for 920(g) and D200) are 198 3-mol»1-K—1 and 76 Jomol—loK—l, respectively. Assume the standard boiling point of heavy water is 101 °C. 6. —124 Jamel—ioK—i 0A. 122 3omojm1.K_1 "122 JomeiwloK—l http:flange}.bprub.com/seedonloontent/default.asp?WCI:pgDispiay%5FQuiz&WCEmta... 11/30/2009 Quiz: CH301 Practice Exam 3 Fall 2009 Page 7 of 11 @c. 2 Jomol—16K~1 1), m2 }emol—1oi<~1 (DE. 124 Jamel—loK—l 31. Consider the acids HF, i-iCl, HBr, ali of which have similar geometries and would form-similar crystal structures at low temperatures. What strategy would you use to rank the deviation from ideality in predicting positional entropy? ‘3) A. Kinetic moiecuiar theory ‘ )B. Quantum mechanics R— . Intermolecular force theory C} E). Molecular orbitai theory (3E. Vaience bond theory 32. When 63.26 g of Acetone, CH3COCH3, are frozen, 6.23 id of heat are reieased. What is the enthalpy of fusion of Acetone at 25°C? Give your answer in k] - mol” 1 to 3 significant figures. 33. 40.6 k] of heat were supplied to 81 g of liquid Acetone, and as a resuit the Acetone vaporized. What is the enthalpy of vaporization of Acetone at 25°C? Give your answer in k3 . mol” 1 to 3 significant figures. 34* What is the enthaipy of sublimation of Acetone at 25°C? Give your answer in k.) - mol" 1 to 3 35. Consider the foliowing numbered processes: 1. 2A + B —-> BC + E 2. 28 —> A + D + E 3. E —> 38 + C Which of the foliowing calculations gives AH for 2A ~i~ D m» C? AHl W AHZ + 1/2 AH3 - B. 1/.:1 AHE — AH2 w 1/2 AHS QC. AHl + AH2 + AH3 [3- - 11’2 AHl ~i~ 0H2 + 1/2 AH3 36. Use the bond enthalpies given in the table beiow to estimate the reaction enthalpy for burning 1 mol of Butane: C4Hw(g) 4» (13/2) 02(9) m» cico2 + 5a20(g) Bond "Mean bond enthalpy .(kJ - moi“1) http://an.geI.bprub.oonusection/content/default.asp?WCIr~pgDisp1ay%SFQuizéRcWCE=ta.. 11/30/2009 Quiz: CIMI301 Practice Exam 3 Fall 2009 Page 8 of 11 CEO 743 0—H 463 Give your answer in k} ' moi“ 1, inctudieg sign, to 4 significant figures. 37. Methane undergoes an exothermic reaction with gaseous Chlorine to form Chloroform: CH4(g) + 382(9) —-—> CHCl3(g) ~2- 3HCi(g) AH° = ~27? k3 Use the bond enthalpies given in the table below to calcuiate the mean CmCI bond enthaipy of Chloroform. Give your answer in kJ A moi” 1, including sign, to 3 significant figures. Mean bond enthaipy (k3 - moi—1) 38. Hot coffee in a vacuum flask (thermos) is an example of a(n) (open, closed, isolated) system. . 39. A piece of a newly synthesized material of mass 25.0 g at 80.0°C is placed in a calorimeter containing 100.0 g of water at 20.0°C. If the final temperature of the system is 24.0°C, what is the specific heat capacity of this material? ‘1 3(0C)"1 “1 3(oc)*1 (TEA. 0.30 1:, 03. 7.46th c. 1.193“ '1h(OC)“1 639.4763: "11°04 0.84 Jog'iwcfl L"; LQLDLQKQ 40. The combustion of 1 mole of octane, C8H18(§), to produce carbon dioxide and liquid water has AHr 2 —5471 i<3tiirraoi”1 at 298 K. What is the change in internal energy for this reaction? A. —5460 loomoi'l O B. ~5482 lemma"1 C} c. 5449 k] moi”jL DD. —5471 k3;moi”‘1 GE. —5493 kitimol"1 41- For the reaction C02(aq) w» C02(g), AE—Er m 19.4 kitjmol'1 at 298. At constant temperature and pressure, which of the foliowing statements is true? 0A. w 2 0 03. AU 2 2.48 k] http://angei.bprub.com/secté.onloontent/defauit.asp?WCImpgDispiay%5FQuiz&WCEmta... 11/30/2009 Quiz: CHBOI Practice Exam 3 Fali 2009 Page 9 of 1 1 @C.AH<AU Gummau 42- For gaseous hydrogen atoms at 298 K is +217. kjmmoifi, the standard enthalpy of formation can be best written as: (SEA. 2 34(9) —~> H49) B. £5 H2(g) —+ We) Go. Hzie) —> 2 We) Go. 2 H2(g) we 4 HCQ) OE. Hig) —+ iinig) 43. What is the standard enthalpy of formation of Brza)? SEA. a positive value. {5 B. a negative value. @C. zero. @D. a positive value if it is forming from ions or a soiid. E) E. a negative value if it is forming from ions or a solid. 44. Calcutate the entropy change for the condensation of 11.5 g of mercury at the normal boiling point 356.5°C. AHvap" = 59.3 kJ/mol. Give your answer in J » K’l, including sign, to 2 significant figures. 45. Caiculate the meiting point of ammonia. Use the foliowing data, given at the melting point of ammonia: Mm; = 5.65 kJ/mol asfuso = 28.93 J/K ; moi Give your answer in K to 3 significant figures. 46. On the basis of the structures of each of the foliowing molecules, predict which would be most likely to have a residual entrepy in its crystal forms at T = O: Q A_ XeF2 O 8- C52 OD. HF 47. What is the correct order of molar entropy? GA. Bram) > 550} > C312(9) > 12(5) . 2(9) > (32(9) > Br20) > 12(5) [35 .1 http://angel.bprub.com/sectioIVcontent/default.asp?WCImpgDisplay%5FQuiz&WCE=ta. .. I 1/3 0/2009 Quiz: CH3OI Practice Exam 3 Fail 2009 Page 10 of 11 (Dc. CI2(9) > 8112(9) > Br2(|) > 12(5) CED. i2(3) > BT26) > BF2(g) > (32(9) 48. Which of the following statements is cosrect? @A, Cat-1180) (at 298 K) has higher moiar entropy than CH4(g), because Cat-£18 is a larger molecule than CH4, and Earger moéecuies have more chemicai bones and can store energy in more ways than smailer molecules. _ CH4(g) has higher moiar entropy than Cal-i180) because gases have a higher entropy than Elquids. QC“ 1.0 g of CH4(g) has the same entropy as 2.0 g of CH4(g) because entropy is an intensive property (a property that is independent of the amount of substance). (1‘; D. A aad C are correct. E. B aad C are correct. Are the foilowing statements True or False? 49. An exothermic reaction is always spontaneous. A. wTrue 50. If AH and A5 are both positive, then AG will decrease when the temperature increases. A. True G B. False 51.. A reaction for which ASr is positive is spontaneous. 6A. Tree 3.. False 52. What is the range of temperatures at which the reaction is spontaneous, at standard conditions? Use the following data ‘ . S§O2(s) + 2C(s, graphite) + 202(9) —+ SiCl4(g) + 2CO(g) 0A. The reaction is spontaneous at alt temperatures. 0 B. The reaction becomes spontaneous below 145 K. C. The reaction becomes spontaneous above 145 K. Q If). The reaction is non5pontaneous at all temperatures. http://angel.bprub.cour/section/content/default.asp?WCI=pgDispIay%5FQuiZcficWCEmta... 1 1/30/2009 Quiz: (II-130$ Practice Exam 3 Fa112009 Page 11 of 11 53, Use the Boltzmann formula to caiculate the entropy at T = 0 of 1.00 mol chlorobenzene, CGHSCJ, where each moiecuie car; be oriented in any of six ways. GA. 0 JDK'l; at T = 0, there is no randomness. 8. ~15 313161 @c. ~30 Jet-('1 (:35. +30 JpK‘l . +15 midi 54. Which of the following is always true for a spontaneous process at constant temperature? Q Av- ASsystem "J" {Assurrounsings = q/T C} B. as > o 0 c. AS a q/T - ASsystem + Assurroundings > O (De. as < q/T 55. The sublimation of soiid carbon dioxide is a spontaneous process. Predict the sign (+, —, or 0) of AGr°, AHF", and ASIP, respectively. ' 56. When calculating the entropy of vaporization of water at 25°C, the dominant contribution is (BA. the molar heat capacity of liquid water. C) B. heating the water from 25°C to 100°C. QC. cooling the water from 100°C to 25°C. @0; the entropy of vaporization of water at its normal boiiing point. .-i.:§ase.£~ieswscsssz http:Hangel.bprub.com/section/conten’r/default.asp'?WCI==pgDispiay%5FQuiz&WCEmta... 1 1/3 0/2009 ...
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This note was uploaded on 03/24/2010 for the course CH 301 taught by Professor Fakhreddine/lyon during the Fall '07 term at University of Texas at Austin.

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Practice Exam 3 (Laude) - Quiz: CH301 Practice Exam 3 F2111...

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