Chem 135 Exam 2 PDF

CHEM 135 – EXAM 2 – Dr. Vedernikov Full Name: ______________________________ First letter of your Last Name: Please PRINT Lecture time: 11:00 am Discussion Section day (circle one): M W Discussion section time (circle one): 10:00am 12:00pm 1:0...

CHEM 135 – EXAM 2 – Dr. Vedernikov Full Name: ______________________________ First letter of your Last Name: Please PRINT Lecture time: 11:00 am Discussion Section day (circle one): M W Discussion section time (circle one): 10:00am 12:00pm 1:00pm 2:00pm “I pledge on my honor that I have not given or received any unauthorized assistance on this examination” Signature Date This exam contains 6 pages in total including this title page:  14 questions on pages 2-5 (do NOT unstaple these pages and the title page)  the Periodic Table of the Elements on the last page (you may detach it) Check if you have all of that before you begin. You may use any blank pages as a scratch paper. Put your answers ONLY in the space provided. Examination rules:  You may not begin until everyone has an exam  When time is called, put your pencil down and remain in your desk  After all exams have been collected, you will be dismissed Question 1: _____/6 pts Question 8: ____/8 pts Question 2: _____/6 pts Question 9: ____/8 pts Question 3: _____/6 pts Question 10: ____/8 pts Question 4: _____/6 pts Question 11: ____/8 pts Question 5: ____/8 pts Question 12: ____/8 pts Question 6: ____/8 pts Question 13: ____/6 pts Question 7: ____/6 pts Question 14: ____/8 pts TOTAL POINTS: _________/100  When performing calculations, pay attention to the number of significant figures in your answer! 1. (6 pts total) Draw one Lewis structure for the following species. Draw the better structure only. The central atom is underlined. Pay attention to the charge. [CN2]2-: H 2. (6 pts total) Consider the following Lewis structure for borazine, B3N3H6: H N H a) (4.5 pts) For this structure calculate the formal charge for the following atoms: B B F.C.(B) = _______________________________________ N N H B H F.C.(N) = _______________________________________ H F.C.(H) = _______________________________________ b) (1.5 pts) Draw one better or equivalent resonance structure for borazine: 3. (6 pts total) Consider the following Lewis structure for XeO3: (3 pts) What is the electron-group arrangement at the xenon atom in XeO3? Answer: ______________________________________________ (3 pts) What is the molecular geometry of XeO3? Answer: ______________________________________________ 4. (2 pts each, 6 pts total) Indicate the hybridization of the valence orbitals of the central atom in the following species: a) : _______; b) _______; c) _______ 2 5. (8 pts total) Consider a partial molecular orbital (MO) diagram for Al2 molecule (see drawing below; all MO’s are numbered from 1 to 8). Use this diagram and: Al 8 Al 6 7 a) list all bonding MO’s or write “none” ________________________ ; 3p x, 3p y, 3pz 3p x, 3p y, 3p z b) list all antibonding MO’s or write “none” ________________________ ; 4 5 c) list all degenerate MO’s (each group separately) or write “none” 3 2 ________________________ ; 3s 3s 1 d) place valence electrons available in the Al2 molecule on the diagram and find the Al-Al bond order: _______________ 6. (2 pts each, 8 pts total) Arrange the following: lowest highest a) P, Cl, Sn, in the order of increasing electronegativity: _________________________________ b) C-O, C-F, C-C, in the order of increasing bond polarity: _________________________________ c) CCl4, CH2Cl2, CH3Cl, in the order of increasing molecular polarity: _____________________________ d) H2C=O, C≡O, CH3-OH, in the order of increasing CO bond energy: ___________________________ 7. (6 pts total) Balance the following reaction equation using least whole numbers: BiCl3 + Na2CO3 + H2O  BiOCl + NaCl + NaHCO3 8. (8 pts total) Molybdenum metal is produced by reduction of MoO3 (molar mass 143.9 g/mol) which, in turn, is prepared by roasting MoS2 (molar mass 160.1 g/mol) in air: 2MoS2(s) + 7O2(g)  2MoO3(s) + 4SO2(g) Calculate the theoretical yield of MoO3 in grams that can be produced by reacting 41.6 g MoS2 with 40.3 g of oxygen gas, O2(g). SHOW YOUR WORK: Theoretical yield of MoO3(s): ____________ g 3 9. (4 pts each, 8 pts total) a) Calculate the volume in mL of 2.35 M H2SO4 that is needed to prepare 125.0 mL of 1.00 M H2SO4. Show your work. Answer: ____________ mL b) What should be the volume in mL of 0.445M NaOH(aq) needed to react with 125.0 mL of 1.00 M H2SO4? 2NaOH(aq) + H2SO4(aq)  Na2SO4(aq) + 2H2O(l) Show your work. Answer: ___________________ mL 10. (2 pts each, 8 pts total) List all products of the following reactions occurring in dilute aqueous solutions and indicate their states. The second reactant is present in excess. Do not balance these equations. If no reaction occurs, write N/R: a) FeSO4(aq) + NH3(aq) + H2O(l)  b) H2S(aq) + NaOH(aq)  c) MgCl2(aq) + CuSO4(aq)  d) CaSO3(s) + HClO4(aq)  11. (2 pts each, 8 pts total) Provide a name or a chemical formula for the following acids or bases: a) acetic acid __________________ b) ________________________________________ HNO2 c) ________________________________________ HClO4 d) manganese(II) hydroxide ___________________ 4 12. (4 pts each, 8 pts total) Provide balanced net ionic equations for the following unbalanced reactions: a) MnCO3(s) + HBr(aq)  MnBr2(aq) + H2O(l) + CO2(g) Net ionic equation: b) (NH4)2S(aq) + Cu(ClO4)2(aq)  NH4ClO4(aq) + CuS(s) Net ionic equation: 13. (2 pts each, 6 pts total) Indicate the oxidation state for the underlined atom: a) NaCN ___ ________ ; b) CrO2Cl2 ___ ________ ; c) Na3Sb ___ ________ (sign) (magnitude) (sign) (magnitude) (sign) (magnitude) 14. (8 pts) Analyze the redox reaction below; oxidation states are indicated above each element symbol. In the boxes provided write formulas of the substances involved in the reaction: Oxidizing agent: Reducing agent: Product of oxidation: Product of reduction: 5  Periodic Table of the Elements 1 18 1 2 1 H He 1.008 4.003 2 13 14 15 16 17 3 4 5 6 7 8 9 10 2 Li Be B C N O F Ne 6.941 9.012 10.81 12.01 14.01 16.00 19.00 20.18 11 12 13 14 15 16 17 18 3 Na Mg Al Si P S Cl Ar 22.99 24.31 26.98 28.09 30.98 32.07 35.45 39.95 3 4 5 6 7 8 9 10 11 12 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 39.10 40.08 44.96 47.87 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.41 69.72 72.61 74.92 78.96 79.90 83.80 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 85.47 87.62 88.91 91.22 92.91 95.94 (97.9) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3 55 56 57-71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 6 Cs Ba La-Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 132.9 137.3 178.5 180.9 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209.0) (210.0) (222.0) 87 88 89-103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 7 Fr Ra Ac-Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og (223.0) (226.0) (261.1) (262.1) (263.1) (262.1) (265) (266) (271) (272) (285) (284) (289) (288) (292) (294) (294) 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 6 Lanthanides La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 138.9 140.1 140.9 144.2 (144.9) 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.0 174.0 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 7 Actinides Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr (227.0) 232.0 231.0 238.0 (237.1) (244.1) (243.1) (247.1) (247.1) (251.1) (252.1) (257.1) (258.1) (259.1) (260.1)