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Unformatted text preview: Last Name First Name Lab Sec. # _; TA: ; Lab day/time: Andreas Toupadakis, Ph.D. Winter 2009 CHEMISTRY 2A Section A Good luck © EXAM 2 Multiple Choice (circle one) Instructions: CLOSED BOOK EXAM! No books, notes, or additional scrap paper are permitted. All information required is contained on the exam. Place all work in the space provided. If you require additional space, use the back of the exam. A scientific calculator may be used (if it is a programmable calculator, its memory must be cleared before the exam). This exam has 10 pages. (1) Read each question carefully. (2) For Parts I and II, there is no partial credit given and only answers marked on this cover page will be graded. (3) The last 2 pages contain a periodic table and some useful information. You may remove them for easy access. (4) If you finish early, RECHECK youp ANSWERS! [email protected] U.C. Davis is an Honor Institution [email protected] 2.®BCDE 0 [email protected] [email protected] 6.ABGDE Possible Points # 1-9 (4 points each) # 10-15 (6 points each) # 16 (16 points) # 17 (8 points) # 18 (4 points) Total Score (100) Toupadakis 2A Winter 2009 EXAM 2 (Page 2 of 10) Part I: Multiple Choice, ConCepts (4 points each) Select the best answer and enter your choice on the cover sheet - No partial credit 1) Which of the following combinations of reactants will yield a precipitate? 9AT2009WINTER A. HCl(aq) + NH3(aq) -——> B. KOH(aq) + NaCl(aq) ——> C. HN03(aq) + LiOH(aq) ——> D. H‘(aq) + OH‘(aq) ——> E. KCl(aq) + AgN03(aq) ——> 2) As a strong electrolyte, NaCl(s): A. when is dissolved in water it completely ionizes into Na‘ and Cl' ions. B. electricity goes through its aqueous solution but the intensity of a light bulb is weak. C. when is dissolved in water it partially ionizes into Na+ and Cl’ ions. D. when is dissolved in water it produces a basic solution. E. when is dissolved in water it produces an acidic solution. @AT2009WINTER 3) We say that oxidation is taking place during a chemical reaction, if there is: A. loss of oxygen B. gain of hydrogen C. gain of electrons D. an increase of the oxidation number of an atom of at least one element. E. all of the above @AT2009WINTER 4) Which of the following mathematical expressions states the ideal gas law? @AT2009WINTER A. V = kn B. V = k/P C. PV = nRT D. Vtotal 3 2Vi E. Rate = k/Ml/z 5) What happens to the volume of a gas when both its pressure and absolute temperature are doubled? ©AT2009WINTER A. increases B. decreaSes C. stays the some D. becomes four times larger E. becomes four times smaller Toupadakis 2A Winter 2009 EXAM 2 (Page 3 of 10) 6) Which of the following atomic models relates to the notion that the electrons of an atom are found in orbits? ©ATZOO9WINTER A. Plum Pudding model (Thomson Model). B. Nuclear Model (Rutherford Model). C. Solar System Model (Bohr Model). D. The orbital Model (Heisenberg-De Broglie - Schrodinger Model). E. none of the above. 7) Consider the hydrogen atom in its ground state. When the hydrogen atom becomes excited: ©AT2009WINTER A. the electron is closer to the nucleus. B. the electron is attracted by the nucleus with a weaker force. C. the electron has lower potential energy. D. the electron is attracted by the nucleus with a stronger force. E. none of the above 8) The Second quantum number of an electron relates to the: @AT2009WINTER size of the orbital it resides. shape of the orbital it resides. orientation in space of the orbital it resides. rotational motion around its own axis. none of the above. m¢0w> 9) Consider a gas in a closed container with a fixed volume. If we double its absolute temperature, its density will: ©AT2009WINTER A. double B. become half C. stays the same D. will become four times larger E. none of the above Toupadakis 2A Winter 2009 EXAM 2 (Page 4 of 10) ______f__________________________.-———————————————-—-— Part II: Multiple Choices, Short Calculations (6 points each) Select the best answer and enter your choice on the cover sheet - No partial credit 10. Consider the mono-electronic cation Liz‘. Calculate the energy in joules of its electron when it is on the first orbit and find how many times it is lower or higher compared to the energy of the electron of a hydrogen atom when it is also on its first orbit. 9AT2009WINTER A. E = - 1.96x10'17 J which is nine times lower than... B. E = 1.96x10'17 J which is nine times lower than... 7, C. E = 1.96x10'17 J which is nine times higher than... E h z - Q R “12;... D. E = -1.96x10"7 J which is nine times higher than... Y\ 1' E. E = —1.96x10'17 J which is equal to... .Q't ”L -—l9 °L‘ ”‘3 E12—Qn .1 1*qQ“ c-9x1.l4¢)xio j: 1—1. mime James {WW 11. Calculate the molar concentration of the CATIONS of an aqueous solution which is: 0.20 M in NaCl and 0.20 M in K2603. @AT2009WINTER A. 0.20 M B. 0.40 M C. 0.60 M D. 0.30 M E. 0.10 M + 0.10/Vi N066 M 0.10 M No 0.10/u KmCOs ”‘3 leQO/Vl KJr 0.60 N CQtiomS Name WinTer‘ 2009 EXAM 2 (Page 5 of 10) 12. AT some TemperaTure, The speeds of 5 gaseous molecules in a conTainer are: @AT2009WINTER u1= 5.3 m/s, U2 = 6.7 m/s, u 3 = 5.5 m/s, u4 = 7.2 m/s, and u5 = 3.9 m/s. The mean speed and rooT-mean-square speed of The molecules will be: A. mean speed = 4.9 ms"1 rooT-mean-square speed = 4.8 ms'1 B. mean speed : 5.7 ms'1 rooT-mean-square speed = 5.6 ms'1 C. mean Speed = 5.8 ms'1 rooT-mean—square speed = 5.7 ms'1 D. mean speed = 5.9 ms’1 rooT-mean-square speed = 5.8 rns'1 E. mean speed = 5.7 ms‘1 rooT-mean-squore speed = 5.8 ms‘1 3 : ui+uei...+us m 5 L17" : \l'si—iuthsfl' ‘@ 13. Consider a mixTure of Three gases A, B, and C. The ToTal pressure of The mixTure, parTial pressure of A(g) and parTial pressure of 3(9) correspondingly are as follows: Pma. = 4.0 aTm, PA : 1.0 aTm, and P3 = 2.0 aTm. If you could randomly pick up 400 molecules from This mixTure, how many molecules would be molecules of “C" gas? ©AT2009WINTER 100 .200 P’cot: PA’VPB*Pc M P : PtoE“'Pl-\'PB 300 ~400 PC, :CL‘O-LO-QO) o-l'w : 1.0 u’fw. Pg: Xc‘PtO‘E (—5 Xe ~_; Local“ 2.32— Ll.Ooil‘w Ll moowzb U1 0 O X6 ' Wig! C m¢€€€0€t§ C A. _' ___. _ - Woe wixl. ., Woflcwfi wix. Ll Name Winter 2009 EXAM 2 (Page 6 of 10) ______________________.__.__———————————————-—- 14. Consider the Balmer—Rydberg equation: v = 3.2881x10‘5 [(1/22) - (1/n2)] s'1 The wavelength of the spectral line for n = 3 will be: A. 656nm B. 486nm C. 434nm D. 410nm E. 339 nm ©AT2009WINTER ’ l is \l 3 6.199 XlOlS<rlq ’g) I 36? leQQlylo l : [+91me g" CCV-q z-w viz—Q : Z’OOXlOm y/tva V qg‘fmo fl 3. 15. How many unpaired electrons are in the ground state electron configuration of an’? ©AT2009WINTER A. 1 , E : FYOW \‘l/Va Periodic. lob/Cc ‘3, D. 4 e. 5 NW [Av/3 ml ed; ov , 1 u MV‘ LRY] gdg L‘Q, OJV‘d Xov Min ‘L—i MW [RY] "£6; ##4## R ve umpolreé e’g Name Winter 2009 EXAM 2 (Page 7 of 10) ________________________'______-—————-—————————— Part III: Partial Credit May Be Given (28 points) Please show all work for calculations 16. (16 points) Balance the following chemical equation by the half-reaction method and show your work. Next, answer the following questions. C2H6O 4’ Oz —'—’ 602+ H20 Note! The above chemical equation is very easy to balance just by inspection. You are NOT asked to balance it by the inspection method. Balancing it by the inspection method will result in zero points for credit. @AT2009WINTER (a) o; J: ufi we“ ————> QHLO Cc) 7307, 3: llHlJr \1c' ——-a gHzo CAM Cd CLHGO iwi 301+ wit/Jr i},e/__> «a an H ‘l+‘i\o so 1C0 Mflgz Czl‘léo JV 307» ————> 1COL+ KHzO ’1 O tH '1 L/b’l The oxidizing chemical species is: 0-2. The reducing chemical species is: C2. H 6 O The name of the oxidized element is: Cay how The name of the reduced element is: OXy 36h The oxidant is: 01 The reductant is: Czl‘lc O The name of the element that gains electrons is: 0* Y 3e“ The name of the element that looses electrons is: CdY loom The chemical species that causes oxidation is: 01, The chemical species that causes reduction is: C7, H6 0 The oxidation number of __C_;_ (give the chemical symbol of the element) increaSes from "_7_’_ to _l'_l’_l The oxidation number of Q (give the chemical symbol of the element) decreases from Q__ to ’7’ F‘fi-'r';='t97hno.nvn Name Winter 2009 EXAM 2 (Page 8 of 10) _____________________________-_.——————————-—-—— 17. (8 points) ©AT2009WINTER There are 18.2 g of a monoprofic acid in 5.00 liters of its 0.10 M aqueous solution. Which is the monoprotic acid? w: i913 HA ) 0.10m ) 6.00L) HA :1. M0619 O”: H A: (0.10 woe HA><§.OOL C06“) :O.§O more \‘kA ’3. L. §O€m VV\(D\ M-M (fifuue) Moéow Mu<< o£ HA 3 y‘ CW4): M-M. t: 18-13/050 WK : KG,“ 04mg”. E; M HA: 1.106 1* +1w°€A 2€.L\6:’L1Oa + X3 ,‘5 nggqa/g AECfl 18. (4 points) (show your work) The energy in kilojoules (kJ) per dozen of photons of AM radio waves with frequency 800 kiloher'rz is: @AT2009WINTER E4 hf per 4i Pino’rovxg. 1. Hz=1§" 2 \l: 900. LcHLT-8OOeXHDZ H2 =9~OOX IOg HZ~ E LP"Y (”0‘0“) '1 V‘V : (6.616XiD-ZL‘3’3XQDOXIOSg") v15) ’19 ’3' ’— 2S3.0Xi0 j :§.30x10 j 2: $30!“) l/‘J PhtA’on . -1! , Raf—H10 (n w P o O“ Name Winter 2009 EXAM 2 (Page 9 of 10) Potentially Useful Information: (You may remove this page for ease of access) Solubility rules: Soluble or mostly soluble compounds: . Group 1, NH4’, chlorates, acetates, nitrates . Halides (except Pb”, Ag’, and ngz‘) o Sulfates (except Srz‘, Baz’, W”, and ngz’) Compounds that are Insoluble . Hydroxides, sulfides (except above rule, and sulfides of group 2) o Carbonates, phosphates, chromates (except above rules) Some useful equations and data: PLEASE NOTE: Important values and equations required for calculations are given with the respective problem. The following may or may not be of any u5e. V 22 En=—RH—2— R:8.314Jmo/"K" 71 m1. -M .- mmo/ TK : 76+ 273 Ax Ap h/47r NA .- 6.022 x 10 23 _nA molar mass (g/mol) Name Winter 2009 EXAM 2 (Page 10 of 10) PERIODIC TABLE Potentially Useful Information: (You may remove This page for ease of access) Key 1 Atomic Number 2 H SymboI He 1.008 Atomic MOSS 4003 220 Eiectronegafivify , 3 4 5 6 7 8 9 10 Li Be B C N O F Ne 6.941 9.012 10.81 12.01 14.01 16.00 19.00 20.18 0.98 1.57 2.04 2.55 3.04 3.44 3.98 — 11 12 13 15 16 17 18 Na Mg AI ' P 5 Cl Ar 22.99 24.31 26.98 28.09 30.97 32.06 35.45 39.95 0.93 1.31 1.61 1.90 2.19 2.58 3.16 - 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca ' 5c Ti V Cr Mn Fe Co Ni Cu Zn Ga 61: As Se Br Kr 39.10 40.08 44.96 47.90 50.94 52.00 54.94 55.85 58.93 58.70 63.55 65.38 69.72 72.59 74.92 78.96 79.90 83.80 0.82 1.00 1.36 1.54 1.63 1.66 1.55 1.83 ' 1.88 1.91 1.90 1.65 1.81 2.01 2.18 2.55 2.96 - 37 39 4o 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb 5 Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In 5n 5b Te I Xe 85.47 87.62 88.91 91.22 92.91 95.94 (98) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3 0.82 o 95 1.22 1.33 1.6 2.16 1.9 2.2 2.28 2.20 1.93 1.69 1.78 1.96 2.05 2.1 2.66 - 38 r 56 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 137.3 175.0 178.5 180.9 183.9 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222) 0.89 1.27 1.3 1.5 2.36 1.9 2.2 2.20 2.28 2.54 2.00 2.04 2.33 2.02 2.0 2.2 - 88 109 a .9 55 Cs 132.9 0.79 87 103 104 105 106 107 Fr R Lr Unq Unp Unh Uns Una (223) (226) (260) - - — - - 0.7 o - - - — - 57 58 59 6o 61 62 64 65 66 67 68 69 70 La Ce Pr Nd Pm Sm 6d Tb Dy Ho Er Tm Yb 138.9 140.1 140.9 144.2 (145) 150.4 157.3 158.9 162.5 164.9 167.3 168.9 173.0 1.10 1.12 1.13 1.14 1.13 1.17 1.20 1.2 1.22 1.23 1.24 1.25 1.1 89 9o 91 92 93 94 95 96 97 98 99 100 101 102 Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No (227) 232.0 (231) 238.0 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) 1.1 1.3 1.5 1.38 1.36 1.28 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 ...
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