CHM 131 - Exam 2 - 2004 Key

CHM 131 - Exam 2 - 2004 Key - COLLEGE OF ARTS AND SCIENCE...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 6
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 8
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: COLLEGE OF ARTS AND SCIENCE 26 October 2004 8:00 am. to 9:30 am. Name: v ID#: 19617 Workshop Meeting Time (day and hour) S AT 7 PM (2 pts. Extra credit) potentially useful information. Please check BEFORE you begin to make sure that you have a complete exam. Please do all your work on the pages provided. You may use the backside of pages for additional work, but please tell us that you are doing so (i.e. an arrow with a note in clear English saying "more work on back"). SHOW ALL WORK. GIVE UNITS for all answers that require them. Partial credit can only be given for those answers for which work is provided. CIRCLE YOUR ANSWER. we ask this so that we don't have to interpret what you intended as your final answer. GOOD LUCK! University of Rochester Rochester, New York 14627-0216 e with H2 and one with Ar. The flasks are also 1) You have two identical 1L flasks and fill on answer for the following 5 placed at STP. Assume the gasses are ideal and circle the correct questions below. a) (5 pts.) Which flask contains more atoms? @ Ar Both flasks the same Neither flask b) (5 pts.) Which flask contains more mass? H2 @ Both flasks the same Neither. flask e) (5 pts.) In which flask is the average kinetieenergg of the molecules higher? H2 Ar Both flasks the same Neither flask d) (5 pts.) If a pinhole leak were placed in each flask, which would lose molecules by effusion at a faster rate? @ Ar Both flasks the same Neither flask e) (5 pts.) Which flask contains fewer than 1022 molecules or atoms? H2 Ar Both flasks the same 2a) (8 pts) Balance the following equation in basic solution: (5 1.’ o ‘3 +1 +3 -2 N02' (aq) + Al (s) —> NH3 (g) + AlOz' (aq) .H /7 aAIO “+Hf+/VH3+®H “ wr/Vof + ELM HARD _. MO; +;H\+H1,O +OH ——a> Mldz-fl-fl/hg b) (7 pts) Balance the following equa 'on in acidic solution: 0 -7. H .— | +5’-—z 12 (s) + 001' (aq) —> C1' (aq)+ 19:" (aq) + _ \ ILt’éHLO—D 13:05 HRH Hoe“ " (OC/IWQHfi‘ac-‘7 letHLO > 5 T ’ ’fizH‘H/Iae' 1—5 or?“ 5 “'9 - A/eeé‘K 30 +0 ffiafii WI 9M +3501 "—‘7 N'z/ 7‘" gilt/O H3 :7 9w LIA/H3’l'g01, ’/7 ML ’I/éHfia MW“ +- 3OL+lZQHZHT~9 QML+4HZO+ Ma‘flzw LIA/H3 Hfl/H31/3CJZ Z/V—L ’1—éH7/O them shown below. 3) Consider the arrangement of bulbs and ideal gases inside a) (10 pts) What are the partial pressures of each Assume the temperature remains constant iii/t Pv 300 K, and ne‘glect the volume of the tubing connecting the bulbs. U53 P‘V‘ : or‘ I: \ \ /\/L V __ hoot. lawn _, ._ PM _C150L><9\4§12rr3( 760.13% —. O. l3? q+m/ BUL (2 _,.. 0501. (wig); ' Hv CQSOL 7éo‘Brr (DA/C : (LOOL satiric Q‘SZDL/ 760 73” EDT: were; Oézom a C b) (fists) What is the molar mass of the gas mixture? +— HL-t _ (233.0%) %%)+@~Olé)(%> mm», @er o.é75+3674:7 :2 c) (60 pts) What is the density of the gas mixture in g/L at 300 K? 7 ._ : Rl :5 Lfl/ T M m:ma_§$ Pv n /v\ R eraM: mo\ar W55 PVZ/EQUQT 37 Wit: 81A; “5‘17! Kl Q : L063 (o‘osm 4) Consider the neutralization of acetic acid with barium hydroxide: chnso2 (aq) + Ba(OH)2 (aq) —> H20 (I) + Ba(C2H302)2 b) (10 pts) Ho A' A’ I: acetic acid SOhltiOl‘l? F § \ 0M: (0 ‘50 “11% (0.1501): 0.075 mo\ or Wfiaf~tochon ’ we, mi 0.075 mo\ 0H. c) (10 pts) What is the concentration of the Ba2+ ions after the acid is neutralized? U“ [603/3 C mo\ 8a i4“: l50mL+lgsmL 721%} Vélume— : yr m0\ 840th: mol 8a : O»o:s7§mo\ [5693», MW}: O‘lgé/M 0‘275’L 5) A sample of Zn metal (molar mass = 65.38 g/mol) reacts completely with an excess of HCl: Zn(s) + 2 BC] (aq) —-> ZnC12 (04) + H2 (8) The hydrogen gas produced is collected over water at 25 °C. You collect 7.80 L of gas and The vapor pressure of water is 23.8 mm measure a total pressure in your container of 0.980 atm. Hg at 25 °C. a) (5 pts) Calculate the pressure of the H2 in the flask in atm. PT '5- PHLO + PHL (Vt/kw ‘/0u~ éollco‘l owcr HLO- ‘ Pill-.5 Ware“ Vapor.) - .n PH : li—l’w: Ofisoam _/ “Womb : @ \no-VC your «15 / 1/ ' 7 01m R41“: O\?{C\+m éo mm b) (15 pts alculate the mass of Zn metal consumed in the reaction in grams. , _, / g 2.7 3. +25 3. (00%! La??? )(RWKB I" 12%;) Imo\ H7, is QFOAMQ {:Fom l m<>\ Z‘n Not 12% :: 0&303 mo‘ 3;“ —,— @303 mol >( 653“ S/mol 7:! I785 at (5‘) c) (5 pts) What percent (by mol) of the total gas in the flask is water vapor? MHLO— 947,6. (“3/7403 A 0,038 —— ’—~ ’ 9’" on? 0L7? 6) Carbon dioxide reacts with calciurn oxide (CaO) and barium oxide (BaO) to produce metal carbonates. Molar mass of CaO = 56.08 g/mol, of BaO = 153.3 g/mol, of C02 = 44.01 g/mol. a) (5 pts) Write two equations representing these two reactions C00 (9 + @9ng ~22 (A Cogs» 604945» + oobcgy /-7 Bacqgcsx flat: PV/KT :7 fl 3W20a516 W" n ‘ gov/H3083 I’f‘" glow/(Meg : LOT X: mo! ' \/ 3 Mol A'\8£> ’- 2: /53.3 H3? : 153$><+ 56.0% (coax—x) :. 617.;Ll>(+— 1‘1039501Km'rx x 30.01% ma\ :7 3 640 2 ©01an15353: H.733 80.0 ’ 0.0mm 2 0.00%?5 mo\ x 56.0%; : 0.5003643 ._ 3/, 1: N\ _ $800 ’ mews (56737” 2 qu = I00 @‘Z’Wfi .. MEAL c) (5 pts) What is the percent composrtion by mass of the Ba, Ca, and O in the mixture? 800 is ’6‘00 10 L7 mas; >/O~'7;—O)<57.éir~8q Cato ‘5 gator ‘ ixrwa Cs (empower #33” “g (9033(03155 7/ 7. '3 Extra Credit Problem (5 pts) (This is hard and if you get this you have earned the 5 pts — work on this ONLY afier you have finished the rest of the test) A 1.00 cm2 cross sectional area of Earth's atmosphere has a pressure of 1 atm = 760 mm Hg at sea level. Given the average radius of the Earth is 6371 km, the density of Hg is 13.6 g/m}, the molar mass of air is 29.0 g/mol, how many molecules are in the atmosphere? 1 L = 10' m , 3 3 \L’ Ogm x loocml : /000 cm?) - m3 . 3_ .‘,§ : \54, lb F mask“; “‘3 3 K w 3 , Mil, /ooocm 60 m 3 V0 1 M5? (/0055 560+ X v 7’ m “Asks 74x1“, .9 @334 3 Potentia Useful Information Avogadro's Number, N = 6.02214' x' 163 mlol“ ' ' ' e‘lm' '='—1'/'7' 5'88 x 10“ C/kg 2X where X = element symbol, A = mass number, Z = charge number Average atomic mass = 2 ai i ; where ai is the abundance of isotope i having mass Mi Metals tend to lose electrons to become cations, M,M2+, etc. Halides tend to gain electrons to become anions, X Surface area of a sphere= 4m2 The mass of N atoms equals the atomic mass in grams Mass of 13C = 13.003355 amu Number of moles = sample mass/molecular mass Volume of a sphere= 4/3rl:r3 number of moles of atom X = [sample mass (g)/molecular mass (g/mol)] [# mol of X/mol of molecules] M = molarity = moles of solute/liters of solution Mass l3C/mass 12C = 1.0836129 The Gas constant R = 0.08206 L-atm/(mol-K) = 8.3145 J/(mol-K) 760 Torr = 1 atm For IDEAL gases: PV=nRT , STP has P = 1 atm and T = 273 K = 0°C For 1 mol of gas at STP: V = nRT/P = 22.42 L Dalton's law of partial pressures states P = 2 Pi 5 6 7 8 9 10 B C N 0 F Ne 10.81 12.01 14.01 16.00 19.00 20.18 13 14 15 17 18 AI Si P CI Ar 26.98 28.09 30.97 35.45 39.95 20 21 22 23 24 26 27 28 29 30 31 32 33 34 35 36 Ca Sc Ti V Cr Fe Co Ni Cu Zn Ga Ge As Se Br Kr 40.08 44.96 47.88 50.94 52.00 55.85 58.93 58.69 63.55 65.38 69.72 72.59 74.92 78.96 79.90 83.80 37 38 39 4O 41 42 43 44 45 46 47 48 49 50 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Te I Xe 85.47 87.62 88.91 91.22 92.91 95.94 (98) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 127.6 126.9 131.3 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 132.9 137.3 138.9 178.5 180.9 183.9 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222) 88 89 Ra Ac 87 F 61 62 63 64 65 66 67 68 69 70 71 m Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.0 175.0 r (223) 226 (227) 94 95 96 97 98 99 100 101 102 103 Pu Md No Lr m Cm Cf Fm (244) (243) (247) (247) (251) (252) (257) (258) (259) (260) ...
View Full Document

Page1 / 10

CHM 131 - Exam 2 - 2004 Key - COLLEGE OF ARTS AND SCIENCE...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online