09-01 - What is the major species present in a solution of...

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Unformatted text preview: 9/1/2010 What is the major species present in a solution of acetic acid buffered at pH = 7. pKa = 4.75 O O H C What is the major species present in a solution of acetic acid buffered at pH = 7. pKa = 4.75 O A. B. H H C H C O H Ka = H C H O H O H H C H C O H = 10-4.75 A. B. H H C H C O H Ka = = 10-4.75 = 102.25 note: The pH of blood is about 7. note: The pH of blood is about 7. What is the ratio of acid to conjugate base if the pH = pKa? pKa = 4.75 O Fluoroacetic acid a stronger acid than acetic acid. pKa = 4.75 A. B. H H C H C O H Ka = = 10-4.75 A. true B. false =? 1 pKa = 2.59 Why is fluoroacetic acid stronger than acetic acid? Why is acetic acid stronger than ethanol? pKa = 4.75 pKa = 4.75 energy pKa = 2.59 pK pKa = 16 pK 1 9/1/2010 Why is acetic acid stronger than ethanol? Why is acetic acid stronger than ethanol? A. inductive effects pKa = 4.75 δ δ pKa = 4.75 A. A. inductive effects B. resonance effects C. neither of these D. both of these C. C. neither of these D. both of these B. resonance effects pKa = 16 pKa = 16 9 10 HO O N O OH O O O O O OH O O O 11 12 2 9/1/2010 dirt from Easter Island HO O a sewer in Sardinia 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 (B) hydrogen atoms are added to each carbon atom until its valancy is four. N O OH O O O O O OH O O N O O O O OH O O OH O O O O rapamycin cephalosporin 13 rapamycin a cephalosporin 14 What is the formula of the cephalosporin? A. C10H12N2O4S HO O How many rings are present in rapamycin? A. 1 HO O B. C9H10NO4S C. C10H12N2O3S D. C12H14NO4S O O O OH O O B. 2 C. 3 D. 4 O O O OH O N O OH O O N O O OH O O O O rapamycin a cephalosporin 15 rapamycin a cephalosporin 16 Pipercolic acid, an amino acid, is a substructure of rapamycin. Constitutional isomers are structures with the same same molecular molecular formula but different connectivities. different connectivities. H H + C N C C or N H N constitutional isomers N H O OH N H O OH pipercolic acid pipercolic acid 17 18 3 9/1/2010 Choose the structure(s) that is (are) constitutional isomers of pipercolic acid. 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 19 20 The following two molecules are identical. A. true B. false The following two molecules are identical. A. true B. false O OH H O HO H H N N H H O OH HO O H N H N H pipercolic acid pipercolic acid 21 22 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 OH H O N H OH H O O H O N H bent A N H bent B OH O linear C HO 23 O H H H N pipercolic acid 4 9/1/2010 25 5 ...
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