Exam I answer key_1

Exam I answer key_1 - Midterm Examination I CHM 231 Spring...

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Unformatted text preview: Midterm Examination I CHM 231 Spring, 2006 Dr. Gust Time limit: 50 minutes ' \ ‘ Total points = 100 Answer on Pearson machine-grading sheets by marking response A, B, C, D or E. BE SURE TO ENTER YOUR LAST AND FIRST NAMES, AND YOUR 10-DIGIT ASU ID NUMBER ON THE FORM. DO NOT SUPPLY YOUR BIRTH DATE. THE QUESTIONS BELOW ARE EACH WORTH 3 POINTS 1. What is the ground-state electronic configuration for oxygen (atomic number 8)? (A) 1s22s22px22py22p,‘.1s22s22px22py12pz1 (C) [Ne]3s23px23py13pzl (D) [He]2822px22py22pzl 2. Which element has the electronic configuration ls22s22p4? (A) Ne (B) F @o (D) C (E) s 3. How many electrons are in the valence shell of nitrogen? (A) 1 (B) 2 (C) 3 (D) 4 @5 4. How many electrons are in the valence shell of the hydrogen ion, H“? o (B) 1 (C) 2 (D) 3 (E) 4 5. Judging from its relative position in the periodic table, which element in the set below is most electronegative? (A) B .F (C) o (D) C (E) N 6. Does the bond below have its polarity indicated correctly? C ,. +—O_ .yes (B) no 8 5 10. 11. 12. 13. Which is a correct Lewis structure for the carbonate ion, C032'? .,e .. ..® :9: :Q: :9: e .. /C .. . .. .. .. \ -' /C~ - ~- 4Q .. :o=c=o-o: 0’ be .0/ be ,0 ca .. . . (B) ~ . . @ . . (D) 6 Which bond in sodium acetate, CH3COONa, is ionic? (A) (A) C-H (B) c-o @o-Na (D) 0-0 (B) c-c Which bond is most polar? (A) C-H .C-Cl ‘- (C) C-I Using the VSEPR model, predict the bond angles for the atom in the box. H H H—l—c—o—H H H (A) 180° (B) 90° @ 109,5° (D) 120° What is the hybridization of the atom in the box in problem 10? (A) sp (B) spz @5103 (D) 53p (D) 52p Using the VSEPR model, predict the bond angle for the atom in the box. H—C:-—-——Cl H H (A) 180° (B) 90° (C) 109,5° .120° Which of the following molecules has a carboxyl functional group? 0 o o / ' HaC-C: Hac—df H3C-C/: (A) CH3CH2-OH (3) CH3 (c) H OH 14. In the acid-base reaction below, what is the conjugate acid of ammonia (NHg)? NH3 + HCl —+ (A) H+ (B) H30+ @NH.+ (D) Cl‘ (E) NH; 15. The pKa of a strong acid is: (A) numerically larger than that of a weak acid. .numerically smaller than that of a weak acid. 16. Niacin (K3 = 1.4 x 105) is: (A) a stronger acid than aspirin (Ka = 3.3 x 10"). .a weaker acid than aspirin (Ka = 3.3 x 10"). 17. In the following acid-base reaction, the pKa of ammonium ion (NH4+) is 9.24 and that of hydronium ion (H30+) is —1.74. Indicate the letter of the true statement. NH4+ + H20 = NH3 + H30+ (A) The equilibrium in the reaction lies toward the right (toward NH3). The equilibrium in the reaction lies toward the left (toward NH4+). 18. A Lewis base is: (A) a proton donor .an electron pair donor (C) an electron pair acceptor (D) 31:3 19. Which statement about constitutional isomers is not true? (A) Constitutional isomers have the same molecular formula. (B) Constitutional isomers have the same molecular weight. C Constitutional isomers have different physical properties. _ éfi Constitutional isomers have the same connectivity of atoms. Consider the following alcohols a through h: a b C 20. Which structural formulas represent the same compound? (A) a&gandb&c B) e&ganda&d e&danda&g (D) aandbanddande 21. Which structural formulas represent constitutional isomers? 22. Using the IUPAC nomenclature system, which structure corresponds to 3-ethyl-2,4,5- trimethyloctane? Vii @ (B) W 23. What is the name for the foIIOWing alkane? CH3(CH2)4(I3HCH2CH3 CH2CH3 (A) 3-pentylpentane B) 6-ethyloctane 3-ethyloctane ( ) 1,1-diethylhexane 24. Which of the following molecules has the cis configuration at the multiple bond? \ O (A) 0A (B) M @ (D) _ 25. In the E, Z nomenclature system, which group below has the highest priority? (A) —CH3 .—c1 (C) —H (D) ——NH2 (E) —OH 26. Which of the following alkenes shows cis-trans isomerism? (A) 1-pentene (B) 3-ethyl-2-pentene (C) 2-methyl-2-pentene . 2-hexene THE QUESTIONS BELOW ARE EACH WORTH 2 POINTS 27. Is the compound below a terpene? (A) yes .no 28. Is the compound below a terpene? 29. The most important reaction) of alkanes is combustion with oxygen to form C02 and water. .true (B) false 30. Dodecane, C12H26, an unbranched alkane, dissolves easily in water. (A) true false 31. Octane boils at a higher temperature than hexane. .true (B) false 32. In ethylcyclohexane, the ethyl group is most stable in the axial position. (A) true false 33. Cis and trans isomers are found only in alkenes. (A) true false 34. In the chair conformation of cis-1,4-dimethylcyclohexane, one of the methyl groups must always be equatorial. @ true (B) false 35. Ethene gas causes bananas to ripen. true (B) false 36. Benzene is one example of an alkyne. (A) true false 37. Branched chain alkanes boil at a lower temperature than straight chain alkanes with the same number of carbon atoms. true (B) false ...
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