177Exam2KeyF06

177Exam2KeyF06 - DR. THOMAS J. GREENBOWE FALL 2006 THIS...

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Unformatted text preview: DR. THOMAS J. GREENBOWE FALL 2006 THIS EXAM CONSISTS 0F 21 QUESTIONS ON 6 PAGES BEAM PARTS POINTS SCORE Pgfi I Page 2 24 pts Pan II Pages 3 & 4 24 pts 12311111 Page 4 22 pts Page 5 30 pts TOTAL 100 pts CHEM 177 NAME HOUR EXAM II OCTOBER 2, 2006 NOTE: THE METHOD YOU USE IN SOLVING QUESTIONS MUST BE CLEARLY SHOWN IF YOU ARE TO RECEIVE FULL CREDIT. QUESTIONS ARE WRITTEN ON BOTH SIDES OF PAGE CONTAINS USEFUL INFORMATION AND A PERIODIC TABLE. THIS SHOULD BE REMOVED AND USED FOR ADDITIONAL REFERENCE AND SCRATCH PAPER. DO NOT PUT ANSWERS ON THE TEAR AWAY PAGE. EACH PAGE. RECIT. SECT. Teaching Assistants and Recitation Sections Name Ram Adhikary Tanya Gupta Wei Huang Susan Lorge Tim Mauldin Sean Nedd Kerry Riley Sean Riley Robert Roggers Salil Sabnis Suzanne Sander Heather Spangler Laine Stewart Ben Tang Ka King Yan Chad Yuen gtfififififi ‘ -"1 . if - 15:: g Seem 23, 25 11 10, 19 2, 29 4, 17 8, 15 5, 30 3, 12 13, 16 14, 22 24, 26 7, 9 6, 20 21, 28 18, 27 Ti_m: 10:00, 12:10 8:00 4: 10, 2: 10 9:00, 10:00 12: 10, 1:10 2:10, 10:00 12: 10, 11:00 11:00, 9:00 9:00, 11:00 10:00, 8:00 12:10, 2:10 1:10, 3:10 1:10, 4:10 5:10, 4:10 2:10, 3:10 8:00 THE LAST 8 RECIT. INSTR. r... \rL 2 PART I — Multiple Choice. (8 questions at 3 pts each = 24 pts total) 1. 8. 1,4 Co2+ and NO; b) NO; and Br‘ in solution. @ molecules Which of the following are strong electrolytes? 1) HO 2) HCZH3O2 3) NH3 b) 1,3,4 c)1,2,3,4 A weak electrolyte exists predominately as a) atoms b) ions d) electrons e) an isotope 4) KCl d) 1,2,4 6) 2.4 Which ion(s) isfare spectator ions in the formation of a precipitate of AgBr via combining aqueous solutions of CoBr2 and AgNO3? Co'Brztafi) rZASNQJ (at) --’> LASBrU‘) r- Co (NOBJZU? 0) (302+ and Ag+ (1) Br" e) N03" The balanced net ionic equation for precipitation of CaCO3 when aqueous solutions of LiZCO3 and CaCl2 are mixed is a) 2Li+(aq) + CO32‘(aq) a Li,C0,(aq) Caz*(aq) + CO3Z‘(aq) —> CaC03(s) b) 2Li+(aq) + 2Cl‘(aq) —> 2LiCl(aq) e LiZCO3(aq) + CaClz(aq) —> 2LiCl(aq) + CaCO3(s) c) Li*(aq) + Cl‘(aq) —> LiCl(aq) Which of the following are strong acids? 1) HI 2) HNO3 3) HF b)1,2,3,4 0) 1,3,4 4) HBr a) 3,4 d) 2,3,4 Silver chloride has a similar structure to sodium chloride but does not dissolve in water. One reason for this might be that a) the ions are too large to dissolve. b) the ions are too small to dissolve. c the melting point of the salt is too high. ® the attractions between the ions are too strong for water molecules to separate them. e some ions are too light for gravity to pull them down. The combustion of propane (C3H3) in the presence of excess oxygen yields C02 and H20. \ (.0 was; x EL—E C.H.(g) + 5 Oxg) a 3 coxg) + 4 H.0(g) S'wuol 02. When 2.5 mol of 02 are consumed in the reaction, moi of CO2 are produced. b) 3.0 c) 5.0 d) 6.0 e) 2.5 1.5 Calculate the oxidation number of the chlorine in perchloric acid, HClO4, a strong oxidizing agent. +7 a) —l b) +4 0) +5 e) none of the above is the correct oxidation number 3 PART II — Multiple Choice. (6 questions at 4 pts each = 24 pts total) 9. Sulfur and oxygen react in a combination reaction to produce sulfur trioxide, an environmental pollutant: 2 S + 3 02 -> 2 SO3 In a particular experiment, the reaction of 1.00 g S with 1.00 g 02 produced 0.80 g of SO3 (molar mass = 80.07). The % yield in this experiment is a) 30 b) 296 c) 21 d) 88 e) 48 10. The following diagrams represent the reaction of A2 (shaded spheres) with 32 unshaded spheres). Identify the limiting reactant and write a balanced equation for the reaction. a) A2 is the limiting reactant; A + 3 B —> AB3. b) A2 is the limiting reactant; A2 + 3 B2 —> 2 AB3. 0 B2 is the limiting reactant; A + 3 B —> AB3. ED: is the limiting reactant; A2 + 3 B2 -> 2 AB3. 11. What is the molarity (M) of an aqueous solution containing 22.5 g of sucrose (CIZHZZOH) (molar mass = 342) in 35.5 mL of solution? a) 0.0657 b) 1.85 x 103 (E) 1.85 d) 3.52 c) 0.104 1:135 CiLHu'ON 1 M “M CKH 0" : 0.065"? ml [\1 = 03653 Mi 342.5 Ct'LHLIaV CILHuPu 0.039?“— 12. What is the concentration (M) of an aqueous methanol solution produced when 0.200 L of a 2.00 M solution was dlluted to 0.800 L? MN‘ : Mag-Va a) 0.800 b) 0.200 @ 0.500 d) 0.400 e) 8.00 lflL=ML= 2.00m; .lOOL): o_9ooM V2. 0. {(00 L. 13. Which picture below correctly shows the orientation of water molecules around a positively charged ion in solution? (Unshaded spheres represent hydrogen atoms, shaded spheres represent oxygen atoms, gray sphere represents a positive charged ion.) 4 14. The following pictures represent aqueous solutions of three acids HX, HY, or HZ, with water molecules omitted for clarity. Unshaded spheres represent hydrogen atoms or ions and shaded spheres represent X, Y, or Z atoms or ions. Which of the three is the strongest acid, and which is the weakest? a) HX is the strongest acid and HY is the weakest acid. b) HY is the strongest acid and HX is the weakest acid. @ HY is the strongest acid and H2 is the weakest acid. d) H2 is the strongest acid and HY is the weakest acid. PART III — Problems. Show all work. Answers should include appropriate units and contain the correct number of significant figures. (52 pts total) 15. (8 pts) A compound that is composed of carbon, hydrogen, and oxygen contains 70.60% C, 5.90% H, and 23.50% 0 by mass. The molecular weight of the compound is 136 amu. What is the molecular formula? CgHBO2 b) C8H4O c) C4H4O d) CQHIZO e) C5H(,02 Q; \meC. r = 5W8 mic 30.605 /n..0i )c {90 NW 5-89molc. : if; :2 (“#1) Sites, Hi lle/z..ou3n -' * (46w! 0 I 0 5,...” (J _'—9 Of [MAO ‘ of: ’|‘{6 MOIO M : i36 :1 I I firmdd‘ 2‘3 J 3 A; 005 53/ 63 Brig—(25'- 16. (6 pts) What is the concentration (M) of sodium ions in 4.57 L of a 0.847 M Na3P solution? a) 0.847 b) 3.87 c) 0.185 @ 2.54 e) 0282 Lfi§7L Y 034:} "W' [Oast 3nd Us?“ - [I 4 M61 Mal" ‘ IL, 7M: m p " ' i. I M 1. we ; lama 4,5?4. b 17. (8 pts) A 36.3 mL aliquot of 0.0529 M HZSO4(aq) is to be titrated with 0.0411 M NaOH(aq). What volume (mL) of base will it take to reach the equivalence point? (All of the acid is neutralized.) H,so4(aq) + 2NaOH(aq) —> Na,so,(aq) + 2H20(€) 93.6 b) 46.8 c) 137 d) 1.92 e) 3.34 0.0363 L x 0.0;2‘7 ma H1809 ,./ amalgam: ._. 0,0032% Mt New? I L— [mi HzSOc/ M: 1%“ L: 531. =MML0”: Oo‘BsL or fisma M awn Mot Haw ’E’ (Cl—Z 0-0100 [Q‘- Q 04,00 M\ Check x. 2M __ W I 0.0530ka 118/ Q 5 Wt: 18. (2 pts) Problem #18 is the bonus question. This is the only optional problem on the exam. A solution is prepared by adding 1.60 g of solid NaCl to 50.0 mL of 0.100 M CaClz. What is the molarity of chloride ion in the final solution? Assume that the volume of the final solution is 50.0 mL. 0.747 b) 0.647 c) 0.132 d) 0.232 e) 0.547 :25 3mm WWI/act .osvo (— 19. a) (8 pts) Calculate the mass of ammonia (molar mass = 17.01) that can form when 3.82 g of magnesium nitride (molar mass = 72.93) is allowed to interact with 7.73 g of water (molar mass 18.00). Mg3N2 + 3H20 —> 2NH3 + 3 Mgo 33231433101): ELM; ,. twat UH: K (BojA/HJ (00.8 “7311i (“‘0' “73'0" “*4 “’3 (In—not HzO Kauai/UH: UHLL. [UH ¥‘%38Hloxts,05 Hzox ZMIHZOYW" 1% j J b) (2 pts) Identify the limiting reagent. M a; 3 A]?— 20. (12 pts) Classify the following chemical reactions using as many correct terms as appropriate. List A: single-displacement, double-displacement, combustion, decomposition, combination List B: oxidation—reduction, acid—base, precipitate formation a) Mgrs) + 2AgN03(aq) 4 mm + Mg(N03)z(aq) List A: wave memm b) 2HNO3(aq) + Ba(OH)2(aq) —> Ba(NO3)2(aq) + ZHZOU?) List Aibbksk dd MW " List B: 0L - at“ c) CH4(g) + 202(g) --> C02(g) + 2112003) List A: CPw-bxu -Ov\ 21. (8 pts) Complete and balance each chemical equation. Use the Solubility Guidelines to indicate the physical state of each product produced ( 8 solid, “aq” aqueous, “g” gas, “2” liquid). Also, write the net ionic equation. a) _NaZS(aq) + _Zn(NO3)2(aq) —> 2 NQNO3 Cast) 1- ga zficcut)r ngoi) b) 3 K2C03(aq) + iFeCldaq) -* 6 KC! (at J 11- 1:8 ZCCO 10—3 C 5) Fewest) :- (9:20.51 ~52 J09; J30) 511.4559!" 9°99) 6 ABBREVIATED RULES OF SOLUBILITY OF SALTS AND BASES IN WATER All nitrates, chlorates, and acetates are soluble except the acetates of Ag and Hg(€), which are moderately soluble. Practically all sodium, potassium, and ammonium salts are soluble. All chlorides, bromides, and iodides are soluble except those of Ag, Hg(I) and Pb(II). All fluorides are soluble except those of Mg, Ca, Sr, Ba, and Pb(II). All sulfates are soluble except those of Sr, Ba, and Pb(ll), which are insoluble, and those of Ca and Ag, which are moderately soluble. All carbonates, sulfites, phosphates, oxalates, and chromates are insoluble except those of Na’“, K”, NHL All sulfides are insoluble except those of the alkali and alkaline earth metals and NHJ. All hydroxides are insoluble except those of the alkali metals. The hydroxides of Ca, Sr, and Ba are moderately soluble. Periodic Table of the Elements 1A BA 1 2 H He 1.01 4.00 2A 3A 4A 5A 6A 7A 14 15 16 17 2 13 3 4 5 6 7 B 9 10 Li Be BB B C N O F Ne 6.94 9.01 10.8 12.0 14.0 16.0 19-0 20-2 1 12 1 38 4B 513 613 713 f—““'—‘ 13 23 Na Mg 6 7 11 12 5 8 9 10 23.0 24.3 19 20 23 24 25 26 27 28 K Ca V Cr Mn Fe Co Ni 39.1 50.9 52.0 54.9 55.8 58.9 58.7 37 38 39 40 41 42 43 44 45 46 Rb Sr Y Zr Nb Mo Tc Ru h d 85.5 87.6 88.9 91.2 92.9 95.9 (98) 101 57 13 14 15 16 17 18 A1 Si P 5 CI Ar 27.0 : 31.0 32.1 35.5 39.9 3 4 21 22 29 30 31 32 33 34 35 36 Sc Ti CU Zn Ga Ge As Se Br Kr 40.1 45.0 47.9 53-5 65.4 69.7 72.6 74.9 79.0 79.9 83-8 47 48 49 50 51 52 53 54 b T 1 Xe 103 106 108 112 115 119 122 128 127 131 56 7 73 74 75 76 77 78 79 BO 81 82 83 84 35 86 C5 Ba La Hf Ta W Re 05 |r Pt Au Hg Tl Pb Bi Po At Rn 133 137 139 178 181 184 186 190 192 195 197 201 204 207 209 (209 (210)1222) 87 88 89 104 105 106 107 108 109 110 Fr Ra Ac Rf Db Sg Bh HS Mt BS (223) 226 227 (261) (262) (263) (262) (265) (266) (281) 68 69 70 71 Lanthanides Tm Yb Lu 140 141 144 (145) 150 152 157 159 162 165 167 169 173 175 90 91 92 93 94 100 101 102 103 Th Pa U Np Pu No Lr 232 231 238 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) (260) ...
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This note was uploaded on 03/26/2008 for the course CHEM 177 taught by Professor Greenbowe during the Fall '06 term at Iowa State.

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177Exam2KeyF06 - DR. THOMAS J. GREENBOWE FALL 2006 THIS...

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