Problem 32
What is the overall shape of benzene, and what hybridization do you expect for each carbon?
Problem 36
Propose structures for molecules that meet the following descriptions: (a) Contains two \(s p^{2}\) -hybridized carbons and two \(s p^{3}\) -hybridized carbons (b) Contains only four carbons, all of which are \(s p^{2}\) -hybridized (c) Contains two sp-hybridized carbons and two \(s p^{2}\) -hybridized carbons
Problem 37
Why can't molecules with the following formulas exist? (a) \(\mathrm{CH}_{5}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{~N}\) (c) \(\mathrm{C}_{3} \mathrm{H}_{5} \mathrm{Br}_{2}\)
Problem 38
Draw a three-dimensional representation of the oxygen-bearing carbon atom in ethanol, \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\), using the standard convention of solid, wedged, and dashed lines.
Problem 39
Oxaloacetic acid, an important intermediate in food metabolism, has the formula \(\mathrm{C}_{4} \mathrm{H}_{4} \mathrm{O}_{5}\) and contains three \(\mathrm{C}=\mathrm{O}\) bonds and two \(\mathrm{O}-\mathrm{H}\) bonds. Propose two possible structures.
Problem 40
Draw structures for the following molecules, showing lone pairs: (a) Acrylonitrile, \(\mathrm{C}_{3} \mathrm{H}_{3} \mathrm{~N}\), which contains a carbon-carbon double bond and a carbon-nitrogen triple bond (b) Ethyl methyl ether, \(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}\), which contains an oxygen atom bonded to two carbons (c) Butane, \(\mathrm{C}_{4} \mathrm{H}_{10}\), which contains a chain of four carbon atoms (d) Cyclohexene, \(\mathrm{C}_{6} \mathrm{H}_{10}\), which contains a ring of six carbon atoms and one carbon-carbon double bond
Problem 41
Potassium methoxide, \(\mathrm{KOCH}_{3}\), contains both covalent and ionic bonds. Which do you think is which?
Problem 44
Why do you suppose no one has ever been able to make cyclopentyne as a stable molecule?
Problem 45
Allene, \(\mathrm{H}_{2} \mathrm{C}=\mathrm{C}=\mathrm{CH}_{2}\), is somewhat unusual in that it has two adjacent double bonds. Draw a picture showing the orbitals involved in the \(\sigma\) and \(\pi\) bonds of allene. Is the central carbon atom \(s p^{2}\) - or sp-hybridized? What about the hybridization of the terminal carbons? What shape do you predict for allene?
Problem 46
Allene (see Problem \(1.45\) ) is related structurally to carbon dioxide, \(\mathrm{CO}_{2}\). Draw a picture showing the orbitals involved in the \(\sigma\) and \(\pi\) bonds of \(\mathrm{CO}_{2}\), and identify the likely hybridization of carbon.
