Chemistry: An Atoms-Focused Approach

Thomas R. Gilbert, Rein V. Kirss, Natalie Foster

Chapter 19

Organic Chemistry: Fuels, Pharmaceuticals, and Modern Materials - all with Video Answers

Educators

Chapter Questions

Problem 1

How many degrees of unsaturation does each of the hydrocarbons shown in Figure P19.1 have? (FIGURE CANNOT COPY)

Alice .

Alice .

Numerade Educator

Problem 2

Which of the hydrocarbons in Figure $\mathrm{P} 19.2$ are constitutional isomers of each other? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 3

Figure $\mathrm{P} 19.3$ shows the carbon-skeleton structures of four organic compounds found in nature as fragrant oils. Which are alkenes? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 4

Which of the three molecules shown in Figure P19.4 acrylonitrile (found in barbeque smoke), capillin (an antifungal drug), and pargyline (an antihypertensive drug)-does not contain the alkyne functional group? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 5

Which molecules in Figure $\mathrm{P} 19.5$ are considered aromatic compounds? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 6

Benzyl acetate, carvone, and cinnamaldehyde are all naturally occurring oils. Their carbon-skeleton structures are shown in Figure P19.6. Which ones contain an aromatic ring? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 7

In polypropylene, (EQUATION CANNOT COPY)he methyl groups can be in one of two positions with respect to each other (Figure $\mathrm{P} 19.7):$ (a) on the same side of the carbon-carbon backbone or (b) on opposite sides. Many possible variations exist for (b). One form of the polymer in bulk is rigid and resists deformation; the other is soft and rubbery. Suggest which structure gives rise to which set of properties and explain your choice. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 8

The three polymers shown in Figure P19.8 are widely used in the plastics industry. In which of them are the intermolecular forces per mole of monomer the strongest? (FIGURE CANNOT COPY)
(a) Polyethylene
(b) Poly(vinyl chloride)
(c) Poly( 1,1 -dichloroethylene)

Alice .

Numerade Educator

Problem 9

Silly Putty Silly Putty is a condensation polymer of dihydroxydimethylsilane (Figure $\mathrm{P} 19.9$ ). Draw the condensed structure of the repeating monomer unit in Silly Putty. (FIGURE CANNOT COPY)

Arpit Gupta

Numerade Educator

Problem 10

Orlon and Acrilon Fibers Figure P19.10 shows the carbon-skeleton structure of polyacrylonitrile, which is marketed as Orlon and Acrilon. Draw the Kekulé structure of the monomeric reactant that produces this polymer. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 11

Rubber is a polymer of isoprene. It is sometimes called polyisoprene. There are two forms of polyisoprene (Figure P19.11): cis-polyisoprene is the soft, flexible material we associate with the term rubber; gutta-percha,
a. Draw the monomeric units of cis- and transpolyisoprene.
b. Consider the structures of the polymers and comment on why one form is rubbery and the other hard. (FIGURE CANNOT COPY)

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 12

Use representations $[\mathrm{A}]$ through $[\mathrm{I}]$ in Figure $\mathrm{P} 19.12$ to answer questions a-f.
a. Identify the functional group present in each $[\mathrm{B}],[\mathrm{D}],[\mathrm{E}],[\mathrm{F}]$ and $[\mathrm{H}]$
b. Which polymers were formed by addition?
c. Which polymers were formed by condensation?
d. Which functional groups reacted
to form the condensation polymers?
e. Which polymer structures likely result in rigid, hard materials?
f. Which polymer structures likely result in flexible, stretchable, soft materials? (FIGURE CANNOT COPY)

Arpit Gupta

Numerade Educator

Problem 13

List the different sets of hybrid orbitals (valence bond theory) used to describe bonding in organic compounds. What combination of single and multiple bonds is possible with each hybridized set?

Alice .

Numerade Educator

Problem 14

What is the principal difference between an oligomer and a polymer formed from the same monomer?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 15

Is the interstitial alloy tungsten carbide (WC) considered to be an organic compound?

Alice .

Numerade Educator

Problem 16

Calcium carbide, $\mathrm{CaC}_{2},$ was once used in miner's lamps. Reaction of $\mathrm{CaC}_{2}$ with water yields acetylene which, when ignited, gives light. Is calcium carbide considered an organic compound?

Alice .

Numerade Educator

Problem 17

Which of the functional groups in Table 19.1 are polar?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 18

Which of the compounds in Table 19.1 should be water soluble?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 19

If the average molar mass of a polyethylene sample $\mathrm{A}$ is twice that of sample $\mathrm{B},$ which sample begins to soften at a higher temperature? Explain why.

Alice .

Numerade Educator

Problem 20

Which of the following properties of polyethylene increases as the number of monomer units per molecule of the polymer increases? (a) melting point; (b) viscosity;
(c) density; (d) C:H ratio; (e) fuel value

Alice .

Numerade Educator

Problem 21

Do linear and branched alkanes with the same number of carbon atoms all have the same empirical formula?

Alice .

Numerade Educator

Problem 22

If an alkane and a cycloalkane have equal numbers of carbon atoms per molecule, do they have the same number of hydrogen atoms?

Alice .

Numerade Educator

Problem 23

What is the hybridization of carbon in alkanes?

Alice .

Numerade Educator

Problem 24

Figure P19.24 shows the carbon-skeleton structures of hexane and cyclohexane. Are hexane and cyclohexane constitutional isomers? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 25

Why isn't cyclohexane a planar molecule?

Alice .

Numerade Educator

Problem 26

Which of the simple cycloalkanes $\left(\mathrm{C}_{n} \mathrm{H}_{2 n}, n=3-8\right)$ has a nearly planar geometry?

Alice .

Numerade Educator

Problem 27

Are cycloalkanes saturated hydrocarbons?

Alice .

Numerade Educator

Problem 28

Do constitutional isomers always have the same molecular formula?

Alice .

Numerade Educator

Problem 29

Do constitutional isomers always have the same chemical properties?

Alice .

Numerade Educator

Problem 30

Are constitutional isomers members of a homologous series?

Alice .

Numerade Educator

Problem 31

Draw and name all the constitutional isomers of $\mathrm{C}_{5} \mathrm{H}_{12}$

Alice .

Numerade Educator

Problem 32

Draw and name all the constitutional isomers of $\mathrm{C}_{6} \mathrm{H}_{14}$

Alice .

Numerade Educator

Problem 33

Which of the molecules in Figure P19.33 are constitutional isomers of octane $\left(\mathrm{C}_{8} \mathrm{H}_{18}\right) ?$ Name these molecules. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 34

Which of the molecules in Figure P19.34 are constitutional isomers of heptane $\left(\mathrm{C}_{7} \mathrm{H}_{16}\right) ?$ Name these molecules. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 35

Convert the carbon-skeleton structures in Problem 19.33 to molecular formulas.

Alice .

Numerade Educator

Problem 36

Convert the carbon-skeleton structures in Problem 19.34 to molecular formulas.

Alice .

Numerade Educator

Problem 37

Crude Oil Place the following molecules, all of which are products of the distillation of crude oil, in order in which they would appear in the distillate during simple distillation: $\mathbf{C}_{6} \mathrm{H}_{14}, \mathrm{C}_{18} \mathrm{H}_{38}, \mathrm{C}_{12} \mathrm{H}_{26}, \mathrm{C}_{9} \mathrm{H}_{20}$

Alice .

Numerade Educator

Problem 38

Rank the molecules in Figure $\mathrm{P} 19.38$ in order of decreasing van der Waals forces. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 39

Which has a higher hydrogen-to-carbon ratio: hexane or cyclohexane?

Alice .

Numerade Educator

Problem 40

For linear alkanes, each methylene group $\left(-\mathrm{CH}_{2}-\right)$ in the structure contributes $658 \mathrm{kJ} / \mathrm{mol}$ to the heat of combustion.
Heats of combustion for some cycloalkanes are listed below as a function of ring size. Explain the trend in the data. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 41

Can combustion analysis distinguish between an alkene and a cycloalkane containing the same number of carbon atoms?

Alice .

Numerade Educator

Problem 42

Can their reaction with hydrogen distinguish between an alkene and a cycloalkane containing the same number of carbon atoms?

Alice .

Numerade Educator

Problem 43

Why don't the alkenes in Figure P19.43 have cis and trans isomers? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 44

Why don't alkynes have cis and trans isomers?

Alice .

Numerade Educator

Problem 45

Figure $\mathrm{P} 19.45$ shows the carbon-skeleton structure of carvone, which is found in oil of spearmint. Why doesn't the molecule carvone have cis and trans isomers? (FIGURE CANNOT COPY)

Jil Modi

Rutgers, The State University of New Jersey

Problem 46

Figure $P 19.46$ shows the carbon-skeleton structure of the antifungal compound capillin. Are the $\pi$ electrons in capillin delocalized? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 47

Ethylene reacts quickly with HBr at room temperature, but polyethylene is chemically unreactive toward HBr. Explain why these related substances have such different properties.

Alice .

Numerade Educator

Problem 48

Polymerization of butadiene $\left(\mathrm{CH}_{2}=\mathrm{CHCH}=\mathrm{CH}_{2}\right)$ does not yield the same polymer as polymerization of ethylene $\left(\mathrm{CH}_{2}=\mathrm{CH}_{2}\right)$
a. How could we convert poly(butadiene) into poly(ethylene)?
b. Predict the reactivity of poly(butadiene) with HBr.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 49

Using the average bond strengths given in Appendix 4 estimate the molar heat of hydrogenation, $\Delta H_{\text {hydrogenation }},$ for the conversion of $\mathrm{C}_{2} \mathrm{H}_{4}$ to $\mathrm{C}_{2} \mathrm{H}_{6}$
$$\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}(g)+\mathrm{H}_{2}(g) \rightarrow \mathrm{CH}_{3} \mathrm{CH}_{3}(g)$$

Alice .

Numerade Educator

Problem 50

Using the average bond strengths given in Appendix 4 estimate the molar heat of hydrogenation, $\Delta H_{\text {hydrogenation }},$ for the conversion of $\mathrm{C}_{2} \mathrm{H}_{2}$ to $\mathrm{C}_{2} \mathrm{H}_{6}$
$$\mathrm{CH} \equiv \mathrm{CH}(g)+2 \mathrm{H}_{2}(g) \rightarrow \mathrm{CH}_{3} \mathrm{CH}_{3}(g)$$

Alice .

Numerade Educator

Problem 51

Cinnamon Label the isomers of cinnamaldehyde (oil of cinnamon) in Figure $\mathrm{P} 19.51$ as cis or trans and $E$ or $Z$. (FIGURE CANNOT COPY)

Kevin Zaborsky

Numerade Educator

Problem 52

Prostaglandins, naturally occurring compounds in our bodies that cause inflammation and other physiological responses, are formed from arachidonic acid, an unsaturated hydrocarbon containing four $\mathrm{C}=\mathrm{C}$ bonds and a carboxylic acid functional group. The stereoisomer containing all cis double bonds is shown in Figure P19.52. How many stereoisomers other than this one are possible? Draw the isomer containing all trans double bonds. (FIGURE CANNOT COPY)

Kevin Zaborsky

Numerade Educator

Problem 53

Using data in Appendix $4,$ calculate $\Delta H_{\mathrm{rxn}}$ for the production of acetylene from the controlled combustion of methane: $$6 \mathrm{CH}_{4}(g)+\mathrm{O}_{2}(g) \rightarrow 2 \mathrm{C}_{2} \mathrm{H}_{2}(g)+2 \mathrm{CO}(g)+10 \mathrm{H}_{2}(g)$$ Is this an endothermic or an exothermic reaction?

Alice .

Numerade Educator

Problem 54

Using data in Appendix $4,$ calculate $\Delta H_{\mathrm{rxn}}$ for the production of acetylene from the reaction between calcium carbide and water, given that the $\Delta H_{f}^{\circ}$ of $\mathrm{CaC}_{2}$ is $-59.8 \mathrm{kJ} / / \mathrm{mol}$ $$\mathrm{CaC}_{2}(s)+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow \mathrm{C}_{2} \mathrm{H}_{2}(g)+\mathrm{Ca}(\mathrm{OH})_{2}(s)$$. Is this an endothermic or an exothermic reaction?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 55

Given the following two reactions and thermodynamic data from Appendix 4, estimate $\Delta H_{\mathrm{m}}$ for the hydrogenation of acetylene $\left(\mathrm{C}_{2} \mathrm{H}_{2}\right)$ with one mole of hydrogen gas to make ethylene $\left(\mathrm{C}_{2} \mathrm{H}_{4}\right)$
$\mathrm{HC}=\mathrm{CH}(g)+2 \mathrm{H}_{2}(g) \rightarrow \mathrm{CH}_{3} \mathrm{CH}_{3}(g)$
Acetylene Ethane
$\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}(g)+\mathrm{H}_{2}(g) \rightarrow \mathrm{CH}_{3} \mathrm{CH}_{3}(g)$
Ethylene Ethane

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 56

The heat of hydrogenation of cis- 2 -butene is $-119.7 \mathrm{kJ} / \mathrm{mol}$, whereas that of the trans isomer is $-115.5 \mathrm{kJ} / \mathrm{mol} .$ Draw both isomers and the product of the hydrogenation reaction, and locate them on the graph of relative energy given in Figure P19.56. The condensed structural formula of 2-butene is $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{3}$. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 57

Making Glue Wood glue or "carpenter's glue" is made of poly(vinyl acetate). Draw the carbon-skeleton structure of this polymer. The monomer is shown in Figure P19.57. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 58

The 2000 Nobel Prize in Chemistry was awarded for research on the electrically conductive polymer polyacetylene.
a. Draw the carbon-skeleton structure of three monomeric units of the addition polymer that results from the polymerization of acetylene, $\mathrm{HC} \equiv \mathrm{CH}$.
*b. There are two possible stereoisomers of polyacetylene. Describe the two isomeric forms.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 59

Polyacetylene (see Problem 19.58 ) conducts electricity but has no commercial uses in large part because it is unstable in air, reacting with $\mathrm{O}_{2}$ to produce polymers that contain carbonyl groups and ether linkages (Figure $\mathrm{P} 19.59$ ). Suggest why these changes in composition and structure decrease the conductivity of the polymer. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 60

Substituted polyacetylene can be made by replacing hydrogen atoms with functional groups on the backbone of the polymer (Figure $\mathrm{P} 19.60$ ). The backbone may bend when this is done, decreasing the conductivity of the polymer. Why does bending the backbone of the chain decrease conductivity? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 61

Why is benzene a planar molecule?

Alice .

Numerade Educator

Problem 62

Why are aromatic molecules stable?

Alice .

Numerade Educator

Problem 63

Do tetramethylbenzene and pentamethylbenzene have constitutional isomers?

Alice .

Numerade Educator

Problem 64

Why aren't butadiene $\left(\mathrm{C}_{4} \mathrm{H}_{6}\right)$ and 1,3 -cyclohexadiene $\left(\mathrm{C}_{6} \mathrm{H}_{8}\right)$ considered aromatic molecules? Their carbon-skeleton structures are shown in Figure P19.64. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 65

Pyridine (Figure $\mathrm{P} 19.65$ ) has the molecular formula $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{N} .$ Is pyridine an aromatic molecule? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 66

Is cyclooctatetraene (Figure $\mathrm{P} 19.66$ ) an aromatic compound? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 67

Draw all the constitutional isomers of trimethylbenzene.

Alice .

Numerade Educator

Problem 68

The three isomeric trichlorobenzenes are labeled I, II, and III. As a result of a chemical reaction, one methyl $\operatorname{group}\left(\mathrm{CH}_{3}-\right)$ is added to each isomer. Isomer I forms one monomethyl compound, isomer II forms two monomethyl compounds, and isomer III forms three monomethyl compounds. Draw the structures of the original trichlorobenzene isomers.

Alice .

Numerade Educator

Problem 69

Calculate the fuel values of gaseous benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ and ethylene gas $\left(\mathrm{C}_{2} \mathrm{H}_{4}\right) .$ Does one mole of benzene have a higher or lower fuel value than three moles of ethylene?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 70

Does one mole of gaseous benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ have a higher or lower fuel value than three moles of acetylene gas $\left(\mathrm{C}_{2} \mathrm{H}_{2}\right) ?$

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 71

Explain why methylamine (CH $_{3} \mathrm{NH}_{2}$ ) is more soluble in water than butylamine $\left[\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{3} \mathrm{NH}_{2}\right]$

Alice .

Numerade Educator

Problem 72

Combustion of hydrocarbons in air yields carbon dioxide and water. What other product is expected in the complete combustion of amines?

Alice .

Numerade Educator

Problem 73

Are You Hungry? Serotonin and amphetamine both contain the amine functional group (Figure $\mathrm{P} 19.73$ ). Serotonin is responsible, in part, for signaling that we have had enough to eat. Amphetamine, an addictive drug, can be used as an appetite suppressant. Identify the primary and secondary amine functional groups in these molecules. (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 74

Coffee Caffeine, an active ingredient in coffee, contains four nitrogen atoms per molecule. Aspartame is an artificial sweetener containing two nitrogen atoms. Structures of caffeine and aspartame are shown in Figure P19.74. Which nitrogen atoms represent secondary amines and which ones represent tertiary amines? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 75

Renewable Energy Bacteria of the genus Metbanosarcina convert amines to methane. Their action helps make methane a renewable energy source. Determine the estandard enthalpy of the following reaction from the appropriate standard enthalpies of formation $$\left(\Delta H_{\mathrm{f}, \mathrm{CH}, \mathrm{NH}_{2}}^{\circ}=-23.0 \mathrm{kJ} / \mathrm{mol}\right)$$ $$4 \mathrm{CH}_{3} \mathrm{NH}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(\ell) \rightarrow 3 \mathrm{CH}_{4}(g)+\mathrm{CO}_{2}(g)+4 \mathrm{NH}_{3}(g)$$

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 76

Determine the $\Delta H_{\mathrm{mn}}^{\circ}$ values of the following combustion reactions of methylamine $\left(\Delta H_{f, \mathrm{CH}, \mathrm{NH}_{2}}^{\circ}=-23.0 \mathrm{kJ} / \mathrm{mol}\right)$ $$\begin{aligned}
4 \mathrm{CH}_{3} \mathrm{NH}_{2}(g)+13 \mathrm{O}_{2}(g) & \rightarrow 4 \mathrm{CO}_{2}(g)+4 \mathrm{NO}_{2}(g)+10 \mathrm{H}_{2} \mathrm{O}(\ell) \\
4 \mathrm{CH}_{3} \mathrm{NH}_{2}(g)+6 \mathrm{O}_{2}(g) & \rightarrow 4 \mathrm{CO}_{2}(g)+4 \mathrm{NH}_{3}(g)+4 \mathrm{H}_{2} \mathrm{O}(\ell)
\end{aligned}$$

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 77

Methylamine is a weak base.
a. Use information in Appendix 5 to sketch the titration curve for the titration of $125 \mathrm{mL}$ of a $0.015 M$ solution of methylamine with $0.100 M$ HCl.
b. Label the curve with the $\mathrm{pH}$ of the analyte solution, the $\mathrm{p} K_{\mathrm{a}}$ of the analyte, and with the $\mathrm{pH}$ and titrant volumes halfway to the equivalence point and at the equivalence point.
c. Draw the structures of the species present in the solution at the equivalence point.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 78

The $p K_{b}$ values in Appendix 5 tell us that methylamine is a stronger base than ammonia and that dimethylamine is even stronger. Use the differences in their molecular structures to explain this trend in the strengths of these three bases.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 79

Why are the fuel values of ethanol and dimethyl ether (Figure $\mathrm{P} 19.79$ ) lower than that of ethane? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 80

Would you expect the fuel value of alcohols to increase or decrease as the number of carbon atoms in the alcohol increases?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 81

Why do ethers typically boil at lower temperatures than alcohols with the same molecular formula?

David Collins

Numerade Educator

Problem 82

Which do you expect to be more soluble in water, MTBE or 2,2 -dimethylbutane (Figure $\mathrm{P} 19.82$ )? Explain your answer. (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 83

Clean Skin Disposable wipes used to clean the skin prior to getting an immunization shot contain ethanol. After wiping your arm, your skin feels cold. Why?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 84

Dry Gas In the winter months in cold climates, water condensing in a vehicle's gas tank reduces engine performance. An auto mechanic recommends adding "dry gas" to the tank during your next fill-up. Dry gas is typically an alcohol that dissolves in gasoline and absorbs water. Based on the structures shown in Figure $\mathrm{P} 19.84$ which product would you predict would do a better jobmethanol or 2 -propanol? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 85

Which of the compounds in Figure P19.85 are alcohols and which ones are ethers? Place them in order of increasing boiling point. (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 86

Which of the compounds in Figure P19.86 are alcohols and which ones are ethers? Place them in order of increasing vapor pressure at $25^{\circ} \mathrm{C}$. (FIGURE CANNOT COPY)

David Collins

Numerade Educator

Problem 87

Consult tables of thermochemical data in Appendix 4 for any values you may need to solve Problems 19.87 through 19.90
Calculate the fuel values of diethyl ether and butanol (Figure $\mathrm{P} 19.87) .$ Which has the higher fuel value? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 88

Calculate the fuel value of liquid diethyl ether and methyl propyl ether (Figure $\mathrm{P} 19.88) .$ Which has the higher fuel $$\text { value? }\left(\Delta H_{f, \text { methyl propyl ether }}^{\circ}=-266.0 \mathrm{kJ} / \mathrm{mol} .\right)$$ (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 89

Problem 19.80 asked you to predict whether the fuel value of alcohols increases or decreases with the number of carbon atoms in the alcohol. Calculate the fuel values of liquid methanol and ethanol (Figure $\mathrm{P} 19.89$ ). Does your answer support the prediction you made in Problem $19.80 ?$ (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 90

Which has the greater fuel value: propanol or isopropanol $$\text { (Figure }\mathrm{P} 19.90) ?\left(\Delta H_{\text {fpropanol }, \ell}^{\circ}=-302.6 \mathrm{kJ} / \mathrm{mol}\text { and }\right.$$ $$\left.\Delta H_{\text {filoopropanol,t }}^{\circ}=-318.1 \mathrm{kJ} / \mathrm{mol} .\right)$$ (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 91

Explain why carboxylic acids tend to be more soluble in water than aldehydes with the same number of carbon

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 92

In reference books, diethyl ether (Figure $\mathrm{P} 19.92$ ) is usually listed as "slightly soluble" in water, but 2-butanone is listed as "very soluble." Why is 2-butanone more soluble? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 93

Are butanal and 2 -butanone (Figure $\mathrm{P} 19.93$ ) constitutional isomers? (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 94

Apples Both of the esters shown in Figure P19.94 are found in apples and contribute to the flavor and aroma of the fruit. Are the two compounds identical, constitutional isomers, or stereoisomers, or do they have different molecular formulas? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 95

Can we use combustion analysis to distinguish between ketones and aldehydes with the same number of carbon atoms?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 96

Can we use combustion analysis to distinguish between ethers and ketones with the same number of carbon atoms?

Alice .

Numerade Educator

Problem 97

Resonance forms for acetic acid are shown in Figure P19.97. Which one contributes more to bonding? Explain your choice. (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 98

Figure $P 19.98$ shows resonance forms for acetamide and acetic acid. Does resonance form (a) contribute more to the bonding in acetamide than resonance form (b) contributes to the bonding in acetic acid? Explain your answer. (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 99

What distinguishes an amine from an amide?

Alice .

Numerade Educator

Problem 100

Explain why nylon reacts with acid, whereas polyethylene is inert toward acid.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 101

Which of the compounds in Figure $\mathrm{P} 19.101$ are constitutional isomers of the aldehyde $\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O} ?$ (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 102

Each of the natural products in Figure P19.102 contains more than one functional group. Which of the compounds is an aldehyde? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 103

Which of the compounds in Figure $\mathrm{P} 19.103$ is a ketone? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 104

Propanal and acetone ( 2 -propanone) have the same molecular formula, $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O},$ but different structures (Figure $\mathrm{P} 19.104) .$ Which compound is a ketone? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 105

Plot the carbon-to-hydrogen ratio in aldehydes with one to six carbon atoms as a function of the number of carbon atoms. Does this graph correlate better with the plot of C:H ratios for alkanes or for alkenes?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 106

Plot the carbon-to-hydrogen ratio in carboxylic acids wione to six carbon atoms as a function of the number of carbon atoms. Does this graph correlate better with the plot of $\mathrm{C}:$ H ratios for alkanes or for alkenes?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 107

Esters are responsible for the odors of fruits, including apples, bananas, and pineapples. Figure $\mathrm{P} 19.107$ shows three esters from these fruits. Identify the alcohol and carboxylic acid that react to form these compounds. (FIGURE CANNOT COPY) (a) In pineapples (b) In bananas (c) In apples

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 108

Beeswax The waxy material found in beehives (Figure $\mathrm{P} 19.108$ ) is an ester formed from an alcohol and a carboxylic acid with a long hydrocarbon chain. Identify the alcohol and acid in beeswax. (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 109

Stimulants and Tranquilizers Nicotine is a stimulant found in tobacco, whereas Valium is a tranquilizer. Both molecules contain two nitrogen atoms in addition to other functional groups. Do the nitrogen atoms shown in blue in Figure $P 19.109$ belong to an amine or an amide? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 110

Hot Peppers Piperine and capsaicin are ingredients of peppers that give "heat" to spicy foods. Do the nitrogen atoms shown in blue in Figure $\mathrm{P} 19.110$ belong to an amine
-or an amide? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 111

Consult tables of thermochemical data in Appendix 4 for any values you may need to solve Problems 19.111 through 19.114
Calculate the fuel values of formaldehyde gas and liquid formic acid (Figure $\mathrm{P} 19.111$ ). The $\Delta H_{\mathrm{f}}^{\circ}$ of formaldehyde gas is $-108.6 \mathrm{kJ} / \mathrm{mol}$ and the $\Delta H_{f}^{\circ}$ of liquid formic acid is $-425.0 \mathrm{kJ} / \mathrm{mol} .$ Which has the higher fuel value? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 112

Consult tables of thermochemical data in Appendix 4 for any values you may need to solve Problems 19.111 through 19.114
Calculate the fuel values of liquid formamide and methyl formate (Figure $\mathrm{P} 19.112),$ which have $\Delta H_{f}^{\circ}$ values of
-251 and $-391 \mathrm{kJ} / \mathrm{mol},$ respectively. Assume $\mathrm{NO}_{2}(g)$ is
a product of formamide combustion. (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 113

Consult tables of thermochemical data in Appendix 4 for any values you may need to solve Problems 19.111 through 19.114
Calculate $\Delta H_{\mathrm{mn}}^{\circ}$ for the following reactions of methanogenic bacteria, given $$\Delta H_{f, \mathrm{HCOOH}}^{\circ}=-425.0 \mathrm{kJ} / \mathrm{mol}$$
(1) $\quad \mathrm{CH}_{3} \mathrm{COOH}(\ell) \rightarrow \mathrm{CH}_{4}(g)+\mathrm{CO}_{2}(g)$
(2) $4 \mathrm{HCOOH}(\ell) \rightarrow \mathrm{CH}_{4}(g)+3 \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(\ell)$

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 114

Consult tables of thermochemical data in Appendix 4 for any values you may need to solve Problems 19.111 through 19.114
Calculate $\Delta H_{\mathrm{mn}}^{\circ}$ for the following reactions of methanogenic bacteria: (1) $4 \mathrm{H}_{2}(g)+\mathrm{CO}_{2}(g) \rightarrow \mathrm{CH}_{4}(g)+2 \mathrm{H}_{2} \mathrm{O}(\ell)$
(2) $\quad 4 \mathrm{CH}_{3} \mathrm{OH}(\ell) \rightarrow 3 \mathrm{CH}_{4}(g)+\mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(\ell)$

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 115

Reactions between 1,6 -diaminohexane, $\mathrm{H}_{2} \mathrm{N}\left(\mathrm{CH}_{2}\right)_{6} \mathrm{NH}_{2}$ and different dicarboxylic acids, HOOC(CH $_{2}$ ) $\mathrm{COOH}$, are used to prepare polymers that have a structure similar to that of nylon. How many carbon atoms were in the dicarboxylic acids used to prepare the polymers with the repeating units shown in Figure $\mathrm{P} 19.115 ?$ (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 116

The two polymers in Figure P19.116 have the same empirical formula.
a. What pairs of monomers could be used to make each of them?
b. How might the physical properties of these two polymers differ? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 117

The polyester called Kodel is made with polymeric strands prepared by the reaction of dimethyl terephthalate with 1,4-di(hydroxymethyl) cyclohexane (Figure $\mathrm{P} 19.117$ ). (FIGURE CANNOT COPY) Dimethyl terephthalate 1,4-Di(hydroxymethyl)cyclohexane (dimethyl benzene-1,4-dicarboxylate)
a. Is Kodel a condensation polymer or an addition polymer? What is the other product of the reaction?
*b. Dacron (Figure 19.44 ) is made from dimethyl terephthalate and ethylene glycol. What properties of Kodel fibers might make them better than Dacron as a clothing material?

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 118

Lexan is a polymer belonging to the class of materials called polycarbonates. Figure $\mathrm{P} 19.118$ shows the polymerization reaction for Lexan.
a. What other compound is formed in the polymerization reaction?
"b. Why is Lexan called a "polycarbonate"? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 119

Can all of the terms enantiomer, achiral, and optically active be used to describe a single compound? Explain.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 120

Could a racemic mixture be distinguished from an achiral compound based on optical activity? Explain your answer.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 121

Can stereoisomers of molecules, such as cis and trans $\mathrm{RCH}=\mathrm{CHR},$ also have optical isomers? (R may be any of the functional groups we have encountered in this textbook.) Explain your answer.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 122

The compound $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{Br}_{2}$ exists as a racemic mixture. Draw its structure.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 123

Nutmeg The compound myristicin (Figure $\mathrm{P} 19.123$ ) is in part responsible for the flavor of nutmeg. Limited animal studies on myristicin have shown it may have a small influence on sexual behavior, but large doses cause very unpleasant side effects.
a. The structure shown for myristicin has four double bonds. Are cis and trans isomers of myristicin possible?
*b. How many structural isomers are possible based solely on the arrangement of the groups on the aromatic ring in myristicin? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 124

The condensed structure of a molecule is $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{C}\left(\mathrm{CH}_{3}\right) \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{2} \mathrm{CH}_{3} .$ Draw all the
possible stereoisomers of this compound.

Chloe Schroeder

Chloe Schroeder

Numerade Educator

Problem 125

Which of the molecules in Figure P19.125 do not have any possible constitutional isomers? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 126

Which of the molecules in Figure P19.126 do not have any possible stereoisomers? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 127

How many grams of liquid methanol must be combusted to raise the temperature of $454 \mathrm{g}$ of water from $20.0^{\circ} \mathrm{C}$ to $50.0^{\circ} \mathrm{C} ?$ Assume that the transfer of heat to the water is $100 \%$ efficient. How many grams of carbon dioxide are produced in this combustion reaction?

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 128

Two compounds, both with molar masses of $74.12 \mathrm{g} / \mathrm{mol}$
-vere combusted in a bomb calorimeter with $C_{\text {calorimeter }}=3.640 \mathrm{kJ} /^{\circ} \mathrm{C} .$ Combustion of $0.9842 \mathrm{g}$ of compound A led to an increase in temperature of $10.33^{\circ} \mathrm{C}$ while combustion of $1.110 \mathrm{g}$ of compound $\mathrm{B}$ caused the temperature to rise $11.03^{\circ} \mathrm{C} .$ Which compound is butanol and which is diethyl ether?

Jason Boomer

Numerade Educator

Problem 129

Benzene rings with two methyl groups are called xylenes.
1,4-Dimethylbenzene (para-xylene or $p$ -xylene) and
1,3-dimethylbenzene (ortbo-xylene or o-xylene) have very similar boiling points $\left(138^{\circ} \mathrm{C} \text { and } 139^{\circ} \mathrm{C},$ respectively) \right. but very different melting points $\left(13^{\circ} \mathrm{C} \text { and }-48^{\circ} \mathrm{C}\right.$ respectively). Explain this observation.

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 130

Perfume from Whales Ambergris comes from the intestines of sperm whales and was once used to make perfumes. Ambrein (Figure $\mathrm{P} 19.130$ ) is a constituent of ambergris that, when injected in rats, is known to cause an increase in their sexual activity. a. What functional groups are present in ambrein?
b. How many chiral centers does ambrein have?
c. Are any cis/trans isomers possible for ambrein? (FIGURE CANNOT COPY)

Kendrick Buford

Kendrick Buford

Numerade Educator

Problem 131

Turmeric Turmeric is commonly used as a spice in Indian and Southeast Asian dishes. Turmeric contains a high concentration of curcumin (Figure P19.131), a potential anticancer drug and a possible treatment for cystic fibrosis.
a. Are the substituents on the $C=C$ bonds (nonaromatic) in cis or trans configurations?
b. Draw two other stereoisomers of this compound.
c. List all the types of hybridization of the carbon atoms in curcumin. (FIGURE CANNOT COPY)

Charles Thomas

Numerade Educator

Problem 132

Polycyclic aromatic hydrocarbons are potent carcinogens. They are produced during the combustion of fossil fuels and have also been found in meteorites. Can we use combustion analysis to distinguish between naphthalene and anthracene (Figure $\mathrm{P} 19.132) ?$ (FIGURE CANNOT COPY)

Alice .

Numerade Educator

Problem 133

Identify the reactants in the polymerization reactions that produce the polymers shown in Figure P19.133. (FIGURE CANNOT COPY)

Arpit Gupta

Numerade Educator

Problem 134

Raincoats "Waterproof" nylon garments have a coating to prevent water from penetrating the hydrophilic fibers. Which functional groups in the nylon molecule make it hydrophilic?

Arpit Gupta

Numerade Educator

Problem 135

Draw the carbon-skeleton structure of the condensation polymer of $\mathrm{H}_{2} \mathrm{N}\left(\mathrm{CH}_{2}\right)_{6} \mathrm{COOH} .$ How does this polymer compare with nylon- $6 ?$

Arpit Gupta

Numerade Educator

Problem 136

Putrescine, $\mathrm{H}_{2} \mathrm{N}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{NH}_{2},$ is one of the compounds that form in rotting meat.
a. Draw the carbon-skeleton structures of all the trimers
(a molecule formed from three monomers) that can be formed from putrescine, adipic acid, and terephthalic acid (Figure P19.136). The three monomers forming the trimer do not have to be different from one another. b. A chemist wishes to make a polymer containing putrescine and a 1: 1 ratio of adipic acid to terephthalic acid. What should be the mole ratio of the three reactants? (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 137

Polymer chemists can modify the physical properties of polystyrene by copolymerizing divinylbenzene with styrene (Figure $\mathrm{P} 19.137$ ). The resulting polymer has strands of polystyrene cross-linked with divinylbenzene. Predict how the physical properties of the copolymer might differ from those of $100 \%$ polystyrene. (FIGURE CANNOT COPY)

Jorge Villanueva

Jorge Villanueva

Numerade Educator

Problem 138

Maleic anhydride and styrene (Figure $\mathrm{P} 19.138$ ) form a polymer with alternating units of each monomer.
a. Draw two repeating monomer units of the polymer.
b. Based on the structure of the copolymer, predict how its physical properties might differ from those of polystyrene. (FIGURE CANNOT COPY)

Arpit Gupta

Numerade Educator

Problem 139

Superglue The active ingredient in Superglue is methyl 2-cyanoacrylate (Figure P19.139). The liquid glue hardens rapidly when methyl 2 -cyanoacrylate polymerizes. This happens when it contacts a surface containing traces of water or other compounds containing - OH or - NHgroups. Draw the carbon-skeleton structure of two repeating monomer units of poly(methyl 2-cyanoacrylate). (FIGURE CANNOT COPY)

Arpit Gupta

Numerade Educator

Problem 140

Silicones are polymeric materials with the formula $\left[\mathrm{R}_{2} \mathrm{SiO}\right]_{n}(\text { Figure } \mathrm{P} 19.140) .$ They are prepared by the reaction of $\mathrm{R}_{2} \mathrm{SiCl}_{2}$ with water to yield the polymer and aqueous HCl. Imagine this reaction as taking place in two steps: (1) water reacts with one mole of $\mathrm{R}_{2} \mathrm{SiCl}_{2}$ to produce a new monomer and one mole of $\mathrm{HCl}(a q) ;(2)$ one new monomer molecule reacts with another new monomer molecule to eliminate one molecule of HCl and make a dimer with a $\mathrm{Si}-\mathrm{O}-\mathrm{Si}$ bond. a. Suggest two balanced equations describing these reactions that occur over and over again to produce a silicone polymer.
b. Why are silicones water repellent? (FIGURE CANNOT COPY)

Arpit Gupta

Numerade Educator

Problem 141

Molecules of piperine and capsaicin (see Figure $\mathrm{P} 19.110$ )
-contain amide functional groups.
a. Draw the amine and the carboxylic acid that could react to form these two compounds.
b. Are the non-aromatic double bonds in these molecules cis or trans?
c. Name the functional groups that contain the oxygen atoms in these compounds.

Shahina -

Numerade Educator

Problem 142

The heats of combustion of two constitutional isomers are the same when estimated from average bond energies, but they are different when determined experimentally. Why?

Ahmed Ali

Numerade Educator