09-02 - 9/2/2009 Clicker Clicker quizzes will be important...

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Unformatted text preview: 9/2/2009 Clicker Clicker quizzes will be important in in organic chemistry. A good performance on clicker good quizzes can earn you points toward toward your final grade. Review: Acetic acid has a larger Ka than trifluoroacetic acid. True or False? A. A. Very sure this is true C. Maybe this is true H C C O O H D. Maybe this is false F. Very sure this is false H C C O F C C O O + H O + H B. B. Somewhat sure this is true E. Somewhat sure this is false a clicker Clicker quizzes Workshops Midterms Final Total 60 60 300 180 600 H H H H acetic acid All All exams will be based upon the class quizzes, workshops and and assigned problems F F F C C O O H F F trifluoroacetic acid A question from the gen chem final exam: question While While high temperatures and pressures are needed to produce ammonia from nitrogen in the industrial Born-Haber process, rhizobia found in root nodules of legumes manage to produce ammonia from nitrogen at pressures around 1 atm and temperatures around 300 K because the enzyme nitrogenase _________. A. increases the equilibrium constant for the reaction. B. increases concentration of nitrogen in the cell. C. provides a mechanism with a lower activation energy. N N + H H Born-Haber 200 atms 350-550 °C Fe catalyst H N H HN N + H H Rhizobia 1 atm 60-70 °F H N H H HN NH EA energy energy NN + HH H2N NH2 A. increases the equilibrium constant for the reaction. NH3 N H + N H EB H N H H B. increases concentration of nitrogen in the cell. C. provides a mechanism with a lower activation energy. reaction The chemical formula of a compound can be determined from its chemical structure. (a) each node represents one carbon atom. HO O H C H H C H H What is the formula of rapamycin? A. C51H79 HO O (B) hydrogen atoms are added to each carbon atom until its valancy is four. B. C51H79N C. C51H79NO13 D. C51H79NO O O O OH O N O OH O O O O O OH O O N O O OH O O O O rapamycin 5 rapamycin 6 1 9/2/2009 Pipercolic acid, an amino acid, is a substructure of rapamycin. Constitutional Constitutional isomers are structures with the same are molecular formula but different connectivities. different connectivities. H H + C N C C or N H N constitutional constitutional isomers isomers N H O OH N H O OH pipercolic acid pipercolic acid 7 8 Choose the structure(s) that is (are) constitutional isomers of pipercolic acid. What What does the wedges ( ) mean? H N N H O OH N H O OH N H OH O OH N H H O OH pipercolic acid i B. ii + iii E. ii ii iii C. i + iii F. iii O pipercolic acid A. i + ii D. i 9 10 The following two molecules are identical. A. true B. false The following two molecules are identical. A. true B. false O N H H O OH HO H H N N H H O OH HO O H N H pipercolic acid pipercolic acid 11 12 2 9/2/2009 The following two molecules are identical. A. true B. false Predict the correct shape for the carboxyl group. trigonal pyramidal trigonal planar O O trigonal planar O H C O H N H H O OH N H OH H O O H O bent A N H bent B OH O linear C How do we predict the best molecular shapes? Valence Shell Electron Pair Repulsion theory VSEPR: VSEPR: Electrons assume a geometry that minimizes minimizes their repulsion. C OH C O C C O How do we predict the best molecular shapes? Valence Shell Electron Pair Repulsion theory VSEPR: VSEPR: Electron pairs assume a geometry that that minimizes their repulsion. C OH C O C C O HO O H 13 H H N pipercolic acid How do we predict the best molecular shapes? Valence Shell Electron Pair Repulsion theory VSEPR: VSEPR: Electrons assume a geometry that minimizes minimizes their repulsion. C OH C O O H C C O O H How do we predict the best molecular shapes? HO O O N O O O OH O H O OH O O O O rapamycin 18 3 9/2/2009 How do we predict the best molecular shapes? Using Using VSEPR what shape would be predicted for the what amino amino group in the following structure? A. A. trigonal planar planar B. trigonal pyrimidal B. HO O NH2 O HO NH2 N O OH O O O O O OH O O N O O O O OH O O OH O O O O aminorapamycin 19 aminorapamycin 20 Using Using VSEPR what shape would be predicted for the what amino amino group in the following structure? A. A. trigonal planar planar HO O H N H Using Using VSEPR what shape would be predicted for the what amino amino group in the following structure? A. A. trigonal planar planar HO O N B. trigonal pyrimidal B. B. trigonal pyrimidal B. H H N O OH O O O O O OH O O N O O O O OH O O OH O O O O aminorapamycin 21 aminorapamycin 22 Using Using VSEPR what shape would be predicted for the what amino amino group in the following structure? A. A. trigonal planar planar H N C H N O H C O B. trigonal pyrimidal B. HH What What is the "molecular glue" that holds atoms together to give molecular structures such as rapamycin? rapamycin? HO O H H H N C O O N O O O O O OH O H O O H H C C H 23 H rapamycin 24 4 9/2/2009 electrostatics attraction electrostatics attraction repulsion - + repulsion + hydrogen atom H· - nuclei electrons + repulsion + hydrogen atom H· H· nuclei - repulsion electrons - hydrogen atom H· hydrogen atom H· + H· energy 25 H H H 26 What is the glue  that holds the hydrogen atoms together to form H2? Why is H H more stable than two hydrogen atoms (H·)? more A. The attraction of e1 to e2. B. B. The attraction of n1 to n2. C. The attraction of n1 to e1 and the attraction of n2 to e2. to and to to and to D. The attraction of n1 to e2 and the attraction of n2 to e!. n1 e1 H· + H· e2 n2 n1 e1 H· + H· e2 n2 energy energy H H H 27 H H H 28 electrostatics + repulsion + hydrogen atom H· attraction The The classical electrostatic model for bonding was very successful but it had some difficulties. nuclei - repulsion electrons - A new theory for chemical bonding was necessary. 1. 1. the circulating electrons did not not emit light. 2. 2. the electron did not collapse into into the nucleus. hydrogen atom H· H· H· energy energy strong attraction attraction energy energy 29 H H 30 30 5 9/2/2009 What was this new theory of chemical bonding? A. Gravitational theory. B. Quantum theory. C. Nuclear theory. D. String theory. What was a major understanding that allowed the development of Quantum theory? A. electrons have no mass. B. protons have no mass. C. electrons have wave properties. D. neutrons can be ignored. H· H· H· H· energy energy H H 31 energy energy H H 32 6 ...
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This note was uploaded on 12/25/2009 for the course CHE 320 taught by Professor Ff during the Spring '09 term at SUNY Stony Brook.

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