midterm-2003-2004

midterm-2003-2004 - Problems Set of Mid-term Exam, CHEM...

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Problems Set of Mid-term Exam, CHEM 111, Fall 2003/04 1 CHEM 111 Organic Chemistry I MID-TERM EXAMINATION (Fall Semester, 18 October 2003) Instructor: Dr. Wei-Min Dai Problems Set Note : This is a close-book examination. You are required to complete ALL problems independently. The maximum time is 80 minutes. You can work on the problems in any order you like. Start with the easy problems first and do the hard ones later. Use the Examination Booklet to present your answers. Do not forget to write down your name, student ID number, course title, and date on your Examination Booklet. Insert this problems set into your used Examination Booklet and hand in before leaving the examination room. Total marks are 350 points. 1. Multiple choice problems. Pick up only ONE answer and write it down on the answering booklet. (8 points each; 64 points) (1a) The carbon atom in HCN is: A. sp hybridization and the geometry of HCN is linear B. sp hybridization and the geometry of HCN is bent C. sp 2 hybridization and the geometry of HCN is planar D. sp 3 hybridization and the geometry of HCN is pyramidal (1b) Considering the resonance structures of nitromethane CH 3 NO 2 , select the most accurate statement. ab c d H 3 CN O O H 3 O O H 3 O O N O O H 3 C [long O–O bond] [normal O–O bond] A. a and b are the resonance structures of nitromethane and c is not the resonance structure of nitromethane. B. a , b and c are the resonance structures of nitromethane but c contributes little to the structure of nitromethane because of a weak O–O bond. C. a , b , c and d are the resonance structures of nitromethane but d contributes little to the structure of nitromethane because the positions of both oxygens are changed. D. d is an important resonance structure of nitromethane compared with c . (1c) According to the following values, select the most accurate statement. p K a: HF (3.2), HCl (–6 ~ –7), HBr (–8 ~ –9.5), HI (–9.5 ~ –10) Bond dissociation energy (kJ/mol): H–F (569), H–Cl (431), H–Br (368), H–I (297) Electronegativity: F (4.0), Cl (3.0), Br (2.8), I (2.5) A. HF is most acidic because F - is the most stable halide anion.
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This note was uploaded on 02/27/2010 for the course CHEM CHEM111 taught by Professor Dai during the Fall '06 term at HKUST.

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midterm-2003-2004 - Problems Set of Mid-term Exam, CHEM...

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