CHEM 177 Evening Exam III April 15, Grading Parts Points Score NOTE: To receive full credit on problems, Part A: 15 questions: 75

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1 Dr. Kathy Burke Dr. Irmi Schewe Miller This exam consists of questions on 6 pages CHEM 177 Evening Exam III April 15, 2013 Name K E Y Recitation TA Recitation Section Grading Parts Points Score NOTE: To receive full credit on problems, Part A: 15 questions: 75 you must clearly show all work and your method of determining the answer must Part B: 4 questions: be clear. The final answer must be page 6 23 reported to the correct number of significant figures and have the correct page 7 22 units. Questions are written on both sides of each page. The last page contains Subtotal part B 45 useful information and a periodic table; Part C: (4 EC) 12 the last page should be removed and used TOTAL 120 (+12 ) pts for scratch paper and as a reference. Do not put answers on the tear away page. Name Recitation Sections Exam location Umesh Chaudhary 13,14 Gilman 1002 Adam Feenstra 10 Gilman 1002 Margarita Geraskina 9, 5 Gilman 1002 Jason Goh 19 Gilman 1352 Madhur Joshi 16,18 Gilman 1352 Shalika Khindurangala 7 Lebaron 1210 Nitin Kumar 2,20 Gilman 1652 Chia Cheng, Lin 15,17 Lebaron 1210 Amanda Nguy 21 MacKay 0117 Balcony Vy Nguyen 1,4 Lebaron 1210 Regina Reinig 3,6 Lebaron 1210 Sweta Vangaveti 8,11 MacKay 0117 Main Sagarika Weerasekara 22,12 MacKay 0117 Main Important information for the rest of this semester: Optional exam: April 29, 6:45 to 7:45 pm. The optional exam can replace a missed exam or an exam with an unusually low score. The optional exam is cumulative, all multiple choice questions, and machine graded (same rooms as previous exams). Please use Blackboard to indicate which exam you wish to replace, no later than April 22 at 7 pm. Final exam: May 9, 7 9 pm. The final exam is worth 150 points; it is cumulative, all multiple choice questions, and machine graded (same rooms as previous exams).

You must use a #2 pencil and completely fill in the appropriate circles on the computer scan sheet. 1. 2.

2 Please read the following instructions carefully before proceeding! Part A of your exam will be computer graded. In order for the computer to identify who you are, it is important that you complete the information section properly. You must use a #2 pencil and completely fill in the appropriate circles on the computer scan sheet To help you code the correct circles, first write your last name, first name and middle initial in the boxes (skip a space between each). Then darken the circles that match the letters in the box above it. See the sample to the right. Write the middle nine digits of your ISU identification number in the boxes A I. Do not skip any spaces. Below each number, darken the circle that matches this number. For example, See the sample at bottom right. 3. Write your recitation section number in the special code area, boxes K L. Do not skip any spaces. For example, if you are in section 8, write 08. Again, darken the circle that matches the number above it. See the sample at bottom far right. Parts A & C: Select the one best answer for each question. Place your answer on the computer answer sheet by darkening the proper circle for that question. Your computer scan sheet will be your official answer sheet for Parts A & C. Circle the answer on these sheets for your own reference. Part B: For full credit, show all your work legibly, include units, and report your answer to the correct number of significant figures. All material (exam, answer sheet, scratch paper) must be returned to your TA in order for us to grade your exam. page 2

3 Part A: Multiple Choice: (15 questions at 5 pts. each) Select the one best answer for each question. Place your answer on the computer answer sheet by darkening the proper circle for that question. Your computer scan sheet will be your official answer sheet for Parts A and C. Circle the answer on this sheet for your own reference. Question 1. (5 pts.) The atomic radius generally increases as we move. A) up a group and from left to right across a period B) up a group and from right to left across a period C) down a group and from left to right across a period D) down a group and from right to left across a period E) down a group; the period position has no effect Use the following possible answers for the next two questions: A) P (g) + e P (g) B) P (g) P (g) + e C) P (g) P + (g) + e D) P (g) P (g) + e E) P + (g) + e P (g) Question 2. (5 pts.) Which equation correctly represents the first ionization of phosphorus? Question 3. Question 4. Answer: C (5 pts.) Which equation correctly represents the electron affinity of phosphorus? Answer: A (5 pts.) Which of the following is an isoelectronic series? A) B 5, Si 4, As 3, Te 2 B) F, Cl, Br, I C) S, Cl, Ar, K D) Si 2, P 2, S 2, Cl 2 E) O 2, F, Ne, Na + Question 5. (5 pts.) Predict the products of this reaction: Cl 2 (g) + H 2 O (l) A) HCl (aq) + HOCl (aq) B) 2 Cl - (aq) + H 2 O (l) C) 2 HCl (aq) + O 2 (g) D) 2 HCl (aq) + O 2 - (g) E) Cl 2 (aq) + H 2 O (l) page 3

4 Use the following possible answers for the next three questions: A) PH 3 (g) B) CaCl 2 (s) C) CHCl 3 ( ) D) BCl 3 (g) Question 6. Question 7. Question 8. (5 pts.) Which compound would most likely be ionic? B (5 pts.) Which compound would most likely have non polar covalent bonds? _A (5 pts.) Which compound would most likely have polar covalent bonds, but no overall dipole moment? D Question 9. (5 pts.) Lattice energy is. A) the energy required to produce one mole of an ionic compound from its constituent elements in their standard states B) the energy required to convert a mole of ionic solid into its constituent ions in the gas phase C) the energy given off when gaseous ions combine to form one mole of an ionic solid D) the sum of ionization energies of the components in an ionic solid E) the sum of electron affinities of the components in an ionic solid For the next two questions, consider the covalent compound arsine, AsH 3. Arsine has the following Lewis structure: H As H H Question 10. (5 pts.) The central atom in arsine has bonding pair(s) of electrons and lone pair(s) of electrons. A) one, one B) one, three C) zero, one D) three, one E) three, two Question 11. (5 pts.) The electron domain geometry of arsine is and the molecular geometry is. A) trigonal planar, trigonal planar B) tetrahedral, trigonal pyramidal, C) trigonal planar, bent D) trigonal bipyramidal, see saw E) square planar, T shaped page 4

5 Question 12. (5 pts.) ClF3 has "T shaped" geometry. There are non bonding domains in this molecule. A) 0 B) 1 C) 2 D) 3 E) 4 Question 13. (5 pts.)according to valence bond theory, which orbitals overlap in the formation of the bond in HBr? A) 1s on H and 4p on Br B) 1s on H and 4s on Br C) 1s on H and 3p on Br D) 2s on H and 4p on Br E) 2s on H and 3p on Br Question 14. (5 pts.)the π bond in ethylene, H2C=CH 2, results from the overlap of. A) sp3 hybrid orbitals B) s atomic orbitals C) sp hybrid orbitals D) sp2 hybrid orbitals E) p atomic orbitals Question 15. (5 pts.) Using electronegativity values from the information page, decide which covalent bond would be the most polar. A) C H B) C N C) C F D) O H E) Cl F page 5

6 Part B: For full credit, show all your work legibly on the exam paper, include units, and report your answer to the correct number of significant figures. No work shown = 0 points. Question 16. (4 pts.) Write the condensed electron configuration of a Mn 2+ ion Answer: [Ar] 3d 5 Question 17. Complete and balance the following reactions; include phases. (a) (5 pts.) _2_ K (s) + _2_H 2 O(l) 2 KOH(aq) + H 2 (g) (b) (5 pts.) _1_CO 2 (g) + _1 or 2 NaOH(aq) _NaHCO 3 (aq) or Na 2 CO 3 (aq) + H 2 O(l) (c) (5 pts.) _1_Na 2 O (s) + _1_H 2 SO 4 (aq) Na 2 SO 4 (aq) + H 2 O(l) (d) (4 pts.) _2_Li(s) + _1_S(s) Li 2 S(s) page 6 total points this page

7 Question 18. (a) (5 pts.) Complete ONE of the contributing resonance structures for the acetate ION, CH 3 COO. The skeleton is shown below (three H s attached to first C, first C attached to second C, second C attached to O s); mark all multiple bonds, lone pairs, and formal charges. H :O: ( ) H C C O : (b) (3 pts.). H Estimate the O C O bond angle: 120 (c) (3 pts.). Estimate the H C H bond angle: (d) (3 pts.). What is the hybridization of the carbon atom that is attached to the oxygen atoms? (sp 2 ) (p) or sp 2 Question 19. (8 pts) Using the table of average bond energies below, calculate the H for the reaction in units of kj. H C H H C H (g) + 2 H I (g) > I C C I (g) H H Bond C C C C H I C I C H Bond energy, kj/mole number of bonds broken 1 2 number of bonds formed ΔH rxn = [( ) ( )] kj = 217 kj Answer: ΔH rxn = -217 kj total points this page page 7

8 Part C: Extra credit Questions (3 pts. ea) Select the one best answer for each question. Place your answer on the computer answer sheet by darkening the proper circle for that question. (There will be open spaces for questions 16 to 19.) Your computer scan sheet will be your official answer sheet for Parts A and C. Circle the answer on this sheet for your own reference. Question 20. Ozone is a (an) of oxygen. A) isotope B) allotrope C) precursor D) peroxide E) free radical Question 21. Xenon has been shown to form compounds only when it is combined with. A) something with a tremendous ability to remove electrons from other substances B) another noble gas C) something with a tremendous ability to donate electrons to other substances D) an alkali metal E) an alkaline earth metal Question 22. Which nonmetal exists as a diatomic solid? A) bromine B) antimony C) phosphorus D) iodine E) boron Question 23. The reaction of alkali metals with oxygen produce. A) oxides B) peroxides C) superoxides D) all of the above E) none of the above page 8

9 Information: You may remove this page and use it for scratch paper. Do not put any answers on this page. N A =1 mol = particles/mol FW of compound (number of atoms)(atomic weight) all elements ΔH rxn Σ(bond enthalpies of bonds broken) Σ(bond enthalpies of bonds formed) μ = Q r E el = (κ Q 1 Q 2 )/d 1 D = C m ; D = (debye); C m = (coulomb meters) e = C (coulombs) Scale Conversions: 1 L = 1000 ml = 1000 cm 3 1 pm = cm 1Å = m 1 nm = 10 9 m 1 kj = 1000 J 1A 1 1 H Li Na K Rb Cs Fr (223) 2A 2 4 Be Mg Ca Sr Ba Ra 226 3B 3 21 Sc Y La Ac 227 4B 4 22 Ti Zr Hf Rf (261) 5B 5 23 V Nb Ta Db (262) 6B 6 24 Cr Mo W Sg (263) Periodic Table of the Elements 7B 7 25 Mn Tc (98) 75 Re Bh (262) 8 26 Fe Ru Os Hs (265) 8B 9 27 Co Rh Ir Mt (266) Ni Pd Pt Ds (281) 1B Cu Ag Au 197 2B Zn Cd Hg 201 3A 13 5 B Al Ga In Tl 204 4A 14 6 C Si Ge Sn Pb 207 5A 15 7 N P As Sb Bi 209 6A 16 8 O S Se Te Po (209) 7A 17 9 F Cl Br I At (210) 8A 18 2 He Ne Ar Kr Xe Rn (222) Lanthanides Act inides 58 Ce Th Pr Pa Nd U Pm (145) 93 Np (237) 62 Sm Pu (244) 63 Eu Am (243) 64 Gd Cm (247) 65 Tb Bk (247) 66 Dy Cf (251) 67 Ho Es (252) 68 Er Fm (257) 69 Tm Md (258) 70 Yb No (259) 71 Lu Lr (260)

Fig. 7.11 First Ionization energies for the Elements Fig. 7.14 Electron Affinities Fig. 7.7 Trends in atomic radii H 2.1 Li 1.0 Na 0.

0 Sb 1.9 Bi 1.9 O 3.5 S 2.5 Se 2.4 Te 2.1 F 4.0 Cl 3.0 Br 2.8 I 2.

10 Fig First Ionization energies for the Elements Fig Electron Affinities Fig. 7.7 Trends in atomic radii H 2.1 Li 1.0 Na 0.9 K 0.8 Rb 0.8 Cs 0.7 Be 1.5 Mg 1.2 Ca 1.0 Sr 1.0 Ba 0.9 B 2.0 Al 1.5 Ga 1.6 In 1.7 C 2.5 Si 1.8 Ge 1.8 Sn 1.8 Pb 1.9 N 3.0 P 2.1 As 2.0 Sb 1.9 Bi 1.9 O 3.5 S 2.5 Se 2.4 Te 2.1 F 4.0 Cl 3.0 Br 2.8 I 2.5 Electronegativities for main group elements based on Pauling s thermochemical data EN bond characteristic 1.8 mostly ionic % ionic, 50% covalent mostly polar covalent mostly covalent

PERIODIC TABLE OF THE ELEMENTS

PERIODIC TABLE OF THE ELEMENTS Useful Constants and equations: K = o C + 273 Avogadro's number = 6.022 x 10 23 d = density = mass/volume R H = 2.178 x 10-18 J c = E = h = hc/ h = 6.626 x 10-34 J s c = 2.998 x 10 8 m/s E n = -R H Z 2