2003 Organic Chemistry CHE230-001 EXAM1 key Page 1 of 5 Cover Sheet! EXAM1 CHEM230-001 FALL 2003 PRINT your name legibly on the line below. _____________________________________________________2003 Organic Chemistry CHE230-001 EXAM1 key Page 2 of 5 Name: ______________________ Student ID No:____________ First: You are allowed to have a writing utensil, a calculator and molecular model set at your seat. Please put away all other materials. Second: Place your student identification on your desk. A proctor will come around to check everyone’s ID. Is your name and number on your test? Third: Quickly read through the entire exam. Your goal, as always, is to score as many points as possible. Do not waste time on problems that you can’t do if there are easy questions to do first. Fourth: It is critically important that your answers be written in a clear, unambiguous manner. Answers in which your intentions are unclear may not receive credit. SHOW YOUR WORK! Fifth: READ THE INSTRUCTIONS FOR EACH PROBLEM. answer each question Problem Number Points possible Score 1. 15 _____ 2. 5 _____ 3. 15 _____ 4. 15 _____ 5. 5 _____ 6. 15 _____ 7. 10 _____ 8. 10 _____ 9. 10 _____ Total 100 _____2003 Organic Chemistry CHE230-001 EXAM1 key Page 3 of 5 1. (15 pts) Draw line structures (as the low-energy resonance structures) for the following compounds. Include all lone pairs and include all formal charges (unless the formal charge is zero). Indication regarding how to connect the atoms is present in the molecular formulas given below at left. 1a. BeH2(–2) 1b. HCCNH2 1c. CH3OCH3(+) 2. (5 pts) Compute the degrees of unsaturation in C9H5NCl2; show your work. My answer for 2a: ________ 3a (10 pts) Draw two structural isomers possessing molecular formula O3. You might want to compute the degrees of unsaturation first (hint). 3b. (5 pts) What is the difference between resonance structures and structural isomers? _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________1a 1c 1b 3a #1 3a #22003 Organic Chemistry CHE230-001 EXAM1 key Page 4 of 5 4a. (10 pts) Draw a Newman projection of 1-chloro-1-bromopropane (BrClCHCH2CH3) in its most stable conformation. 4b. (5 pts) Draw a Newman projection of 1,2-propadiene (H2CCCH2). 5. (5 pts) Name the following structure. Partial credit will be awarded. Cl _____________________________________________________ 6. (15 pts) Estimate the bond angles in the following structures. (Fill in the blanks) NO a) The C-N-C bond angle in the amide at left is approximately ____________. b) The Cl-C-Cl bond angle in CCl3(-) is a little less than ____________. c) How are the N-H bonds hybridized in (CH3)2BNH2? ____________. 7. (10 pts) Molecule 7a has ______ signals in the 13C spectrum. (a number!) Molecule 7b has ______ signals in the 13C spectrum. 8a. (5 pts.) Which isomer absorbs light at the longest wavelength (lowest energy)? _____________ 8b. (5 pts) Which isomer absorbs light at the next lowest energy? _____________ (two possible choices, pick one) 9. (10 pts.) Draw a picture of the pi antibond of ethylene (H2C=CH2). 4a 4b 7a
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