Assignment_2_2011_Answers - CHM 1321 Assignment #2 -...

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CHM 1321 Assignment #2 - Answers 1) Draw Lewis structures for the following molecules. Identify the hybridization oft the underlined atoms. a. Cl Al A l 3 sp 2 The "p"orbital is empty b. F B F F B F 3 2 The "p" orbital is empty c. H C N H H O O C H 3 N O 2 3 2 d. (CH 3 ) 3 C + C C C C H H H H H H H H H 2 The "p" orbital is empty e. Pentanal C C C C C O H H H H H H H H H H f. Propanoic acid C C C O O H H H H H H g. Formaldehyde CO H H h. Acetaldehyde C C O H H H H i. 2-methylpentan-1-ol CC C O C H H H H H H H H H H H H H H j. 3-methylpentan-1-amine C C C C C N C H H H H H H H H H H H H H H H
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Assignment 2 - Answers 2 2) Each structure below is missing a charge—assign formal charges to show which atom bears the charge. a. H 3 C OH 2 H 3 C O H H FC (oxygen) = 6-3-2 = +1 b. H 3 C NH 3 H 3 C N H H H FC (nitrogen) = 5-4-0 = +1 c. H 3 C NH 2 H 3 C N H FC (nitrogen) = 5-2-4 = -1 d. H 3 C C CH 3 OH H 3 C C 3 O H FC (oxygen) = 6-3-2 = +1 e. H 3 C C 2 O H 3 C C C O H H FC (carbon) = 4-3-2 = -1 f. CC H H FC (carbon) = 4-3-2 = -1 g. H 3 C C CH 2 O H 3 C C CH 2 O FC (oxygen) = 6-1-6 = -1
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Assignment 2 - Answers 3 3) a. Convert each of the following molecules to a line structure b. Name each compound i. H 3 C C H 2 H 2 C C H 2 CH 3 pentane ii. H 3 C C C H 2 3 O O 2-butanone iii. H 2 C H 2 C C H 2 2 H C H 2 C 3 1-methylcyclohexane iv. H 2 C H 2 C C H 2 2 H C H 2 C 3 3 isopropylcyclohexane OR 1-(1-methylethyl)cyclohexane NOTE: Don’t forget to include the “cyclo” when naming cyclic molecules! 4) Diethyl ether and 1-butanol have similar solubilities in water, but their boiling points are very different. Explain why these compounds have similar solubility properties but different boiling points. O OH solubility 8.4 mL in 100 mL H 2 O bp 35 o C solubility 8.9 mL in 100 mL H 2 O bp 118 o C Each molecule has about the same amount of Van der Waals interactions, and the Van der Waals surfaces are relatively large. Each compound has a dipole, lone pairs on oxygen and is able to hydrogen bond with water. Therefore each compound has similar solubility in water. The hydrogen bonds in butanol are stronger that the dipole interactions in diethyl ether. Butanol has a higher boiling point because of the stronger hydrogen bonds. The intermolecular forces holding the butanol molecules together are stronger than those holding the diethyl ether molecules together. 5) Explain the difference in boiling point for the following pairs of compounds: N CH 3 H N bp 81 o C bp 106 o C and a) Each molecule has about the same Van der Waals ability. N-methyl-pyrrolidine (on the left) is capable of dipole-dipole interactions. Piperidine (on the right) has a dipole and can also hydrogen bond with itself (lone pair of electrons and hydrogen on the nitrogen atom). Therefore Piperidine has the higher boiling
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Assignment_2_2011_Answers - CHM 1321 Assignment #2 -...

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