1. Rank the following rotational isomers of 1,2-dichloroethane in order of increasing stability (least stable to most stable). BAD 2. What functional groups are present in the molecule below? A nitrile and an ester. 3. Rank molecules A, B, and D in order of increasing pKa of the most acidic proton in each. DBA 4. What types of orbitals are used to make bondA in the structure below? sp2 sp3 5. Specify the number of primary carbons in compound A. 36. Which of the following stick drawings (A, B, D, E) represent a potential structure for C5H12? A, B and E 7. Which of the following is a reasonable resonance structure of the molecule in the box below? D 8. Which of the following represents the ground state electron configuration of fluorine anion (F- )? 1s22s22p6 9. Which of the following structures contains a ketone functional group? A and E only10. What are the formal charges on atoms A and B, respectively in the following structure? D A=0, B= +1 11. Determine the orbital hybridization states for atoms A, B, and D. A-sp2, B-sp3, D-sp3 12. Which molecule(s) below contain a nitrogen with a formal +1 charge? D only13. Determine the IUPAC name for the following molecule? 4-ethyl-2,3,5-trimethylheptane First determine the parent name for the molecule by counting the number of carbons in the longest chain. There are 7 carbons in the longest chain as illustrated below. Next, determine the suffix. Since the molecule fits the general formula CnH2n+2, it is an alkane, and in this case, a heptane. Next, the substituents must be identified and placed in front of the parent name in alphabetical order. The three methyl groups are simplified using the number modifier "tri." 14. What is the IUPAC name of the following compound? trans-1-tert-butyl-2-methylcyclopentane The positions of the substituents in this case should be assigned to keep the numbers as low as possible.15. What is the best Lewis structure for H2CO3? (note: charges have yet to be assigned) This choice is best because it has octets for all its atoms (except H, which can share 2 valence electrons max.), and it is the only choice for which each atom would be uncharged. 16. Which of the following statements is false concerning resonance structures? Each atom in a contributing structure must have a completed valence shell While a structure in which all the atoms have filled valence shells will certainly contribute more to the resonance hybrid than those with one or more incomplete shells, resonance structures can be drawn where an octet is not satisfied. The example below illustrates how carbon can sometimes possess only 6 valence electrons and thus behave in a manner consistent with positively charged atoms. 17. Which statement best describes this reaction? An acid-base reaction where NH3 acts as a Lewis base. In order to answer this question, we first need to know the Lewis structures of the molecules in question. Using rules learned in chapter 1, we can see that NH3 possesses a lone pair of electrons, while AlH3 does not. Since no protons where gained or lost from either molecule, neither of them can be Brønsted-Lowry acids or bases. However, we do see that NH3 donates its two electrons to form the new N-Al bond. We know that it is NH3 that donates the electrons because AlH3 does not have electron pairs to donate.18. Which one of the following structures represents a different compound from the other three? 3 19. Which of the following compounds (A, B, D, E) have a dipole moment? BD 20. How many sigma bonds are there in the compound below? 10 21. Which of the following chair structures represents the lowest energy conformation of trans-1-isopropyl-3-methylcyclohexane? B22. Determine the conformational preferences (axial or equatorial) for the two indicated groups in the lowest energy ring flip of the molecule below. A – axial, B - equatorial 23. Which of the following protons (HA, HB, and HD) is most acidic? HB 24. Which of the following structures represents trans-1,2-dimethylcyclohexane? 2 (4.11 in Book) 25. How many Gauche interactions are present in the molecule below as drawn?
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