CHM235 Fall 04 Exam 1 September 22, 2004

Transcription

1 M235 Fall 04 Exam 1 September 22, points + bonus 1. (25-30 points) Draw Lewis Structures for these molecules: (a) The skeleton of is squaric acid (formula = ) is shown below Add pi bonds and LP to make squaric acid a correct Lewis Structure with no formal charges. Show all LP and pi bonds. All of the hybridization of all the carbons are the same. What is it? What are the /_ bond angles? What are the /_ bond angles? umber of sigma bonds (including ) pi bonds (b) The atomic arrangement of ketene, 2 2, is shown below. omplete the structure to make it a correct Lewis Structure. Show all LP and bonds. a b Describe the bonding between a and. What is the hybridization of a? What is the hybridization of? umber of sigma bonds (including ) pi bonds LP e - s 2. (14 points) For the following structures indicate all the formal charges for non- atoms. yanoethyne [ammonia-formaldehyde] 2 3

2 3. (8 pts) For the structures A-D, consider the questions below: A B D (a) Which structure (or structures) contains a positively charged carbon? (b) Which structure (or structures) contains a positively charged nitrogen? (c) Which structure (or structures) contains a negatively charged oxygen? (d) Which structure (or structures) is most stable? 4 (4 points) For the following questions refer to the hypothetical compounds, where A is more electronegative than B A B A A B A A B A A B A (a) What is the shape of 1? A (b) Which compound or compounds are/is polar? 5. (6 pts) Which one of the pairs of isomers will be the most volatile (higher vapor pressure)? Give a short explanation of which intermolecular forces are involved. (a) (b) 3

3 6. (9 points) Resonance. Determine whether the following pairs represent resonance structures. (a) and (b) and (15 points) Acid Base Given these pka values, answer the questions below: Acid Structure pka Methyl amine Methanol Methyl ammonium Acetic Acid 3 5 Which acid is most acidic? Which acid would have the strongest conjugate base? Draw the chemical structure for that base. Predict the direction and Keq for the proton transfer reaction below: Direction Keq 8. (6 points) Molecular rbitals Label the following orbitals of ethylene as σ, σ*, π, or π* based on the shapes and atomic orbitals involved. The bond axis is the - bond..

4 9. (12 pts) Pick the best name for the following alkanes: 2-isopropylpentane 5-isobutyl-4-methylnonane 2,3-dimethylpentane 5-isobutyl-6-methylnonane 2-methyl-3-propylbutane 5-methyl-4-isobutylnonane 2-isopropyl-5-methyloctane 5-methyl-2-isopropyloctane 2,3-dimethylhexane 2-methyl-5-isopropyloctane 5-isopropyl-2-methyloctane 4-methyl-5-isobutylnonane 10. (12 pts) Draw the following alkanes from name. 3-ethyl-2,4-dimethylhexane 4-isopropyl-3,5-dimethyloctane sec-butylcyclopentane 11. (12 points) Functional Groups: ircle and identify all the functional groups below. ALKAES PLEASE. Sulfide is identified as an example ovocain (local anesthetic Euraxil (scabicide) Esiclene (anabolic steroid) yoctol (antiacne)

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6 Points from Page 1 out of points. Page 2 out of points. Page 3 out of points. Page 4 out of points. Total points Total Points out of 125 points.