4.16: Solutions to Selected Problems

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Exercise 4.1.1:

Exercise 4.1.2

Exercise 4.2.1:

Exercise 4.2.2

Exercise 4.3.1

Exercise 4.3.2:

Exercise 4.3.3:

Exercise 4.4.1:

Exercise 4.4.2:

Exercise 4.4.3:

Exercise 4.4.5

Answers to Exercsise 4.4.5, a through i, showing several Lewis structures.

Exercise 4.5.1:

Exercise 4.5.2:

Exercise 4.5.3:

Exercise 4.5.4:

Exercise 4.6.1:

Exercise 4.6.2:

Exercise 4.6.3:

Answers to Exercise 4.6.2, a and b. For a and b, four resonance structures are shown.

Exercise 4.6.4:

Exercise 4.6.5:

Exercise 4.7.1:

Exercise 4.7.2:

Exercise 4.7.3:

Exercise 4.7.4:

a) bromide b) oxide c) fluoride d) carbonate e) nitrate f) nitrite

g) sulfide h) sulfate i) sulfite j) persulfate k) carbide l) nitride m) arsenide

n) phosphate o) phosphite p) iodide q) iodate r) periodate

Exercise 4.8.1:

Exercise 4.8.2:

a) (CH₃)₂CHCH₂CH₂CN b) CH₃CH₂CH(OH)CH₃

c) (CH₃)₂CHCOCH₂CH₃ d) CH₃CH₂CONHCH₂CH₃

Exercise 4.8.3:

Exercise 4.8.4:

Exercise 4.9.1:

Exercise 4.9.2:

Exercise 4.10.1:

a) octahedral.

Answer to Exercise 4.10.1c, with octahedral geometry converted to square planar geometry.

Exercise 4.10.2:

trigonal bipyramidal
This time there could be two different answers.

If the lone pair occupies one of the axial positions, it would be pretty close to three other atoms.

Trigonal bipyramidal geometry transformed to trigonal pyramidal geometry.

If the lone pairs occupies one of the equatorial positions, it would be pretty close to only two other atoms. The other equatorial atoms are pretty far away.

Trigonal bipyramidal geometry transformed to seesaw geometry.

The rule is that the lone pair goes in the less crowded position, so this molecule would be see-saw shaped.

c) Again, there are two possible geometries. One of them would be trigonal planar, a pretty common geometry.

Trigonal bipyramidal geometry transformed to trigonal planar geometry.

Trigonal bipyramidal geometry transformed to tee geometry.

Exercise 4.10.3:

Exercise 4.10.4

a) bent b) pyramidal at O, although tetrahedral at C c) pyramidal

d) see-saw e) tee f) trigonal bipyramidal

g) octahedral h) square pyramidal i) square planar

Exercise 4.10.5:

Exercise 4.10.6:

You may be able to imagine some other possibilites for this number of neighbors, but IF₇ adopts a pentagonal bipyramid shape.

Exercise 4.11.1:

Exercise 4.11.2:

Exercise 4.11.3:

Exercise 4.12.2:

a) propane b) pentane c) hexane

Exercise 4.12.3:

a) 3-methylhexane b) 2,2-dimethylpentane c) 2,3-dimethylbutane

d) 2,2,3,3-tetramethylpentane e) 3,5-dimethylheptane f) 4-ethyl-3,6-dimethyloctane

Exercise 4.12.4

a) cyclopentane b) cyclohexane c) cyclooctane

d) methylcyclobutane e) 1,1,3-trimethylcyclopentane f) 1,3-dimethylcycloheptane

Exercise 4.12.5:

a) 1-hexene b) 2-methyl-2-pentene c) 1-methylcyclohexene d) 2,4,6-trimethyl-2-heptene

Exercise 4.12.6:

a) cyclopentene b) 1,1-dimethylcyclohexane c) 3-hexyne

d) 4-methylcyclohexene e) 1-hexyne

Exercise 4.12.7:

a) tetrahedral b) trigonal planar c) linear

Exercise 4.12.8:

a) methylbenzene b) propylbenzene c) 1,2-dimethylbenzene or o-dimethylbenzene (also o-xylene)

d) 1,3-dimethylbenzene or m-dimethylbenzene (also m-xylene) e) 1,4-diethylbenzene or p-diethylbenzene

f) 2-ethyl-1,4-dimethylbenzene

Exercise 4.12.9:

a) 2,2-dimethylhexanal b) 2-methylcyclopentanone

c) 3-nonanone d) 2,4-dimethyl-2-hexenal

Exercise 4.12.10:

a) butyl propanoate b) N,N-diethylbutanamide

c) 6-methylheptanoic acid d) 4-pentenoic acid

Exercise 4.12.11:

a) 1-chloro-2-methylcyclohexane b) cyclooctanol c) ethyl cyclopentyl ether

d) N-propylcyclohexylamine e), 5,5-dimethylheptan-2-ol f) 3-bromo-4,4-dimethyloctane

g) dibutylamine i) methyl phenyl ether (or anisole) j) ethane thiol k) diethyl thioether

l) triethylphosphine m) butanenitrile n) nitromethane

Note that sometimes a number is located directly in front of the suffix for the group to which it refers.

Exercise 4.12.12

benzene (or aromatic), ketone and ether
bromide, amine and aldehyde
alcohol, thiol and ester
thioether, amide and alkene
alkyne, alcohol and carboxylic acid

Exercise 4.12.13

Exercise 4.12.14

Exercise 4.13.1:

Answer to Exercise 4.13.2, showing combined esterification and phosphorylation of glycerol.

Answers to Exercise 4.13.3, a through h, showing several fatty acids.

Exercise 4.13.4:

Exercise 4.13.5:

If you don't know what the wedged and dashed lines in the drawing mean, don't worry about it. They just represent different orientations in space. You will learn about these representations in a later topic called "stereochemistry".

Exercise 4.13.6:

Exercise 4.13.7:

Exercise 4.13.8:

Answers to 4.13.8, a through e, showing different nucleotides with their names labelled in red.

Exercise 4.15.1:

N^3- would get to a noble gas configuration.
Ta³⁺ would balance the charge in TaN.

Answer to Exercise 4.15.1d, with unit cell filled in with tantalum and nitrogen on the top and bottom layers only.

e) \( \# Ta = (\frac{1}{6})(\frac{1}{2})(4) \) for the acute corners and \((\frac{1}{3})(\frac{1}{2})(4)\) for the obtuse corners = \(\frac{4}{12} + \frac{4}{6} = \frac{4}{12} + \frac{8}{12} =1\)

(note that it's the same outcome as the corners of a cube)

f) \( \# N = \(\frac{1}{4})(8)\) for the edges and \((\frac{1}{2})(2)\) for the faces = \( 2 + 1 =3\)

g) Need 2 more Ta.

Answer to Exercise 4.15.1d, with unit cell filled in with tantalum and nitrogen. There are two atoms of tantalum in layer two.

h) Each tantalum has three nitrogens above and three below it. It's almost octahedral, but the top layer of nitrogens is lined up above the bottom layer rather than being twisted 120 degrees to form an octahedron. The geometry is a trigonal prism.

Answer to Exercise 4.15.1i, with several unit cells filled in with tantalum and nitrogen.

Structure of tantalum-nitrogen lattice, with geometries about different nitrogen atoms labelled as trigonal pyramidal and angular.

Answer to Exercise 4.15.1k. Structure of tantalum-nitrogen lattice, with geometries about different nitrogen atoms labelled as trigonal pyramidal and angular. The lone pairs are removed.

l) The double bonds hold the atoms more closely together than the single bonds.

Answer to Exercise 4.15.1k. Structure of tantalum-nitrogen lattice, with the single tantalum-nitrogen bonds labelled as 212 nanometers and the double bonds labelled as 194 nanometers.

m) You can imagine the molecules stacking together to make a cubic array of TaN.

Answer to Exercise 4.13.1m, showing how the structure of the tantalum-nitrogen solid can be modelled in different forms.