CHEMISTRY 2202 Answer Key Unit 3 Section 1 and 2 Homework Portfolio

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1 hemistry 2202 Unit 3 Section 1&2 Homework Portfolio Page 1 of 5 HEMISTRY 2202 Answer Key Unit 3 Section 1 and 2 Homework Portfolio Value {2} 1. Jon Jacob Berzelius first defined organic chemistry as a branch of chemistry. a) What is vitalism? Vitalism was the idea that organic compounds could only be produced by living things. It was believed that organic compounds contained a life force that was originated in the living thing that produced the molecule. b) Is vitalism still accepted as a theory in chemistry? Why or why not? Vitalism is no longer accepted as a theory in chemistry. This theory was refuted by the work of Fredrich Wohler, who synthesized urea from ionic salts. Once it was recognized that organic compounds could be synthesized from inorganic compounds, organic chemistry was defined as the chemistry of molecular compounds of carbon. {3} 2. Identify the three main sources of organic compounds and provide a unique example of an organic compound from each source. Be original. Source of Organic ompounds Fossil Fuels Plants and animals Human synthesis Example (many possible) Hexane common organic solvent Tetrodoxin toxin from puffer fish Brefeldin B an antiviral fungal derivative {3} 3. Describe the bonding properties of carbon that contribute to the large diversity of organic compounds. arbon possesses 4 bonding electrons and therefore can form four single bonds. Atoms of carbon can bond with each other in long chains, branched chains or cyclic structures. Stable single, double and triple bonds can be formed by the bonding of carbon atoms. This bonding ability of carbon atoms, when coupled with the stable bonds that carbon can form with most other non-metallic elements, results in the great variety of unique organic compounds that can be formed.

2 hemistry 2202 Unit 3 Section 1&2 Homework Portfolio Page 2 of 5 {6} 4. Draw a structural formula for each compound. (a) 2,2,5-trimethylhexane (b) 2-methyl-2-heptene H 3 H H 3 H (c) 5,5-dimethyl-2-hexyne (d) 1-methyl-3-ethylcyclohexane H 2 H H 2 H H3 (e) para-dipropylbenzene (f) 2-phenylbutane H 3 H {5} 5. Provide a IUPA name for each structural formula H 2 H H H 3 H H H3 (a) 2,2,5-trimethylheptane (b) 2-ethyl-1,3-dimethylcyclopentane

3 hemistry 2202 Unit 3 Section 1&2 Homework Portfolio Page 3 of 5 H 3 5. (c) H H H (d) H 3 4-ethyl-2-hexene 4,4,5,5-tetramethyl-2-hexyne (e) o-dimethylbenzene ortho dimethylbenzene 1,2-dimethylbenzene {5} 6. Draw structural formulas for and name five (5) non-cyclic isomers of 6 H 10. H H H 1-hexyne 3-methyl-1pentyne 2-hexyne H H 3-hexyne 4-methyl-1-pentyne {3} 7. What evidence suggests that the bonding in benzene is different than the bonding in cyclohexene? Both molecules are unsaturated compounds containing six carbon atoms bonded to form a cyclic structure. Study of the benzene molecule has shown that all 6 carbon-carbon bonds are the same length and all angles between the con atoms are equal. This suggests that all carbon-carbon bonds are of the same nature. The cyclohexene molecule contains five single carbon-carbon bonds and one double carbon-carbon bond. With different bond lengths bond angles could not be all equal.

4 hemistry 2202 Unit 3 Section 1&2 Homework Portfolio Page 4 of 5 Study has shown the benzene molecule to be planar. With the different bond lengths and bond angles it is expected that cyclohexane would tend to have a tetrahedral shape around singly bonded-carbon atoms, and thus end up with a puckered six carbon ring rather than a flat symmetrical ring. {1} 8. (a) What is fractional distillation? Fractional distillation is the process which refines and separates crude oil into its many fractions based on their boiling points. {2} (b) Briefly describe the fractional distillation of crude oil. rude oil is pumped into a fractional distillation tower. The crude oil is heated and the many fractions of crude oil vaporize and rise up in the tower. The further up the tower they rise, the cooler the fractions become. Because of differences in their boiling points these fractions will condense, and can be collected separately, at different heights within the tower. {1} (c) Why is cracking an important process in oil refining? racking is the breaking of larger hydrocarbon molecules into smaller molecules using either heat or a catalyst. racking is important because it allows for the conversion of larger, less valuable, hydrocarbon molecules which make up a portion of crude oil, into more valuable hydrocarbons which can be used as reactants in the petrochemical industry. {1} (d) Leaded gasoline molecules were highly branched resulting in even combustion reactions. Leaded gas is banned because of the toxic effects of lead. Briefly describe the chemical process that produces highly branched unleaded gasoline molecules. Unleaded gasoline contains highly branched hydrocarbons such as 2,2,4- trimethylpentane. Since branched molecules are not as common in crude oil these branched molecules are produced by the joining of smaller, straightchained, hydrocarbon molecules. This process is called reforming and proceeds either using heat (thermal reforming) or a catalyst (catalytic reforming). {8) 9. Write a structural formula equation for each hydrocarbon reaction. (a) The combustion of 3,3 dimethylpentane. H 7 16 (l) + 11O2(g) 7O2(g) + 8HO 2 (g)

5 hemistry 2202 Unit 3 Section 1&2 Homework Portfolio Page 5 of 5 (b) The cracking of heptane to form propane and another organic product. ( ) 5 heptane + H 2(g) propane + butane (c) The formation of 2-methylpentane from propane. + H 2 3 propane propaneh H 2-methylpentane + H 2(g) (d) The reaction of propene to form a macromolecule. N H H propene N