Chapter 22 Assignment Answers – Organic Chemistry Unit Chapter 22: 37 – 41, 50, 53, 55, 56, 59, 66, 73 37. pentane: CH3CH2CH2CH2CH3 hexane: CH3CH2CH2CH2CH2CH3 38. (a) propane (b) octane (c) pentane 39. Remember… “alkyl” groups are side groups that branch off a longer-chain hydrocarbon. methyl ̶ CH3 ethyl ̶ CH2CH3 propyl ̶ CH2CH2CH3 40. (a) 2-methylbutane (b) 2,3-dimethylbutane (c) 3-methylhexane 41. Alkane molecules are nonpolar because all of the bonds within the molecule are nonpolar bonds. You can make an alkane molecule polar by adding a functional group to it, however. 50. Both structures are the same, because the alternating double bonds don’t really exist! Remember that the carbon-to-carbon bonds in benzene are all identical. 53. When coal that contains a high percentage of sulfur burns, the major air pollutants SO2 and SO3 are by-products. 55. (a) ethyne (b) propane (c) methylbenzene 56. (a) propyne: (b) cyclohexane: (c) 2-phenylpropane (d) 2,2,4-trimethylpentane 66. Methene does not exist. You only have one carbon in the molecule, so a double bond cannot exist within the molecule. 73. Alkanes: all single bonds between C atoms Alkenes: a double bond exists between C atoms Aromatic: a benzene ring exists within the molecule Cycloalkane: “ring” of single-bonded C atoms Chapter 23 Assignment Answers – Organic Chemistry Unit Chapter 23: # 26, 27, 38, 39, 41, 43, 45, 50, 53 26. “R” indicates a carbon chain or ring. 27. (a) (b) (c) 38. (a) halocarbon: R – X (X is any halogen) (b) ketone: (c) ester: (d) amide: 39. From lowest to highest boiling point: CH3CH2CH3 < CH3CHO < CH3CH2OH Only the alcohol molecule can hydrogen bond to itself, giving it the highest boiling point. The middle compound is an aldehyde, and has a partial negative oxygen but not a very partial positive hydrogen, so it cannot hydrogen bond to itself. And propane can only attract with dispersion forces. 41. A carbon-to-oxygen double bond has an electronegativity difference of 1.0, which makes it polar. 43. (a) phenol (d) phenol (b) ether (e) alcohol (c) alcohol 45. (a) carboxyl functional group; ethanoic acid (b) carbonyl functional group; propanone (c) ether functional group; diethyl ether (d) hydroxyl functional group; ethanol 50. Both ethers are soluble in water to some extent, as each is a polar molecule. However, diethyl ether is more soluble because its nonpolar chains are smaller than dihexyl ether. The larger nonpolar chains interfere with water’s dissolving ability. Propane is basically insoluble in water, as it is a completely nonpolar molecule. 53. Ethanoic acid will be more water soluble. The reasoning is the same as in #50 above. .