04 unit 1 sb - quia is also a component of natural gas. propane is a fuel used in gas barbecues....

NEL Section 3.1 Student Book Solutions 125

GETTING STARTED

REFLECT ON YOUR LEARNING

(78)

1. (Sample response) Organic compounds are similar in structure, similar in types of atoms, similar in size, and similar in chemical reactivity.

2. Solubility: “like dissolves like;” compounds that have large nonpolar components tend to be soluble in nonpolar solvents; and compounds that have small nonpolar components and polar groups such as C=O, OH, or NH groups tend to be soluble in polar solvents Melting and boiling points: compounds with strong intermolecular attractions tend to have higher melting and boiling points because more energy is required to separate the molecules.

3. (Sample response) “Organic” means made by plants or animals; compounds that contain carbon atoms; grown without use of synthetic materials.

TRY THIS ACTIVITY: KEEPING BABY DRY WITH POLYMERS

(Page 179)

(a) The addition of table salt causes some of the water to come out of the gel because the presence of sodium ions reduces the attraction of water to the polymer, and thus reduces absorbency. The addition of sucrose or calcium chloride does not produce any change because no sodium ions are added.

(b) Determine the mass of a dry diaper. Add a few millilitres of water to the absorbent surface of the diaper, then hold the diaper vertically and note whether any leakage occurs. Repeat until the first sign of leakage of water occurs. Determine the mass of the wet diaper. Subtract the mass of the dry diaper from the mass of the wet diaper to obtain the mass of water absorbed. Calculate the volume of water absorbed, using the density of water (1.0 g/mL).

3.1 HYDROCARBONS

TRY THIS ACTIVITY: HYDROCARBONS ARE MADE OF…

(Page 180)

(a) The black powder formed is soot: pure carbon.

PRACTICE

(Page 183)

1. (a)

(b)

(c)

126 Unit 3 Student Book Solutions NEL

(d) 2. (a) nonane, C9H20

(b) heptane, C7H16

PRACTICE

(Page 186)

3. (a)

(b)

(c)

(d)

(e)

(f)

4. (a) 1-pentene, C5H10

(b) 1-butyne, C4H6

(c) 2-heptene, C7H14

PRACTICE

(Page 188)

5. (a) CH4 + 2 O2(g) → CO2(g) + 2 H2O(g) (b) 2 CH3CH3 + 7 O2(g) → 4 CO2(g) + 6 H2O(g) (c) HC≡CCH3 + 4 O2(g) → 3 CO2(g) + 2 H2O(g) (d) CH3CH2CH=CHCH2CH3 + 9 O2(g) → 6 CO2(g) + 6 H2O(g)


TRY THIS ACTIVITY: TESTING FATS AND OILS

(Page 189)

(a) The samples that contained only saturated carbon chains (i.e., no unsaturated bonds) do not turn potassium permanganate solution brown. All of these samples were oils (liquids at room temperature).

(b) Experimentally, the samples that turn potassium permanganate brown contain unsaturated carbon chains. Generally, the fats (solids at room temperature) contain saturated carbon chains.

(c) The more solid the sample is at room temperature, the more likely it is that the sample contains saturated carbon chains; the more liquid the sample is at room temperature, the more likely it is that the sample contains unsaturated carbon chains.

PRACTICE

(Page 190)

6. (a)

(b)

(c)

(d)

7. 1-heptene, 2-heptene, and 3-heptene

SECTION 3.1 QUESTIONS

(Pages 190–191)

Understanding Concepts

1. (i) Carbon atoms can share electrons to form covalent bonds. (ii) Carbon atoms can form four bonds. (iii) Carbon atoms can form covalent bonds with other carbon atoms. Therefore, they can join other carbon atoms to form straight chains, branched chains, or ring structures.

Example: decane

2. (a) Alkenes contain one or more carbon−carbon double bonds. (b) Alkynes contain one or more carbon−carbon triple bonds.


3. Double and triple bonds are readily converted to single bonds. Thus, the presence of double or triple bonds in alkenes and alkynes makes them more reactive than alkanes, which have only single bonds.

4. saturated hydrocarbon:

unsaturated hydrocarbon:

5. Since a single carbon atom cannot form a carbon−carbon double bond, no alkene with a single carbon exists. The smallest alkene is therefore ethene, which contains two carbon atoms.

6.

7. There is no ambiguity in the location of the double bond: in ethene, the double bond can only be between the two carbon atoms; and in propene, the double bond is between the middle carbon atom and one of the carbon atoms on either side. In both cases, the structure is the same.

8. The correct name is 2-pentene because the carbon chain is numbered so that the lowest number indicates the location of the double bond. The carbon chain of this molecule should be numbered in the opposite direction.

9. 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O 10.


11.

12. Student answers for the examples will vary.

Front:

Examples Family name and general formula

IUPAC name Common name Structural formula

Alkanes

CnHn+2

butane lighter fluid

Alkenes

CnHn

propene propylene

Alkynes

CnHn−2

ethyne acetylene

Back:

Family Characteristic properties Characteristic functional groups

Intermolecular forces

Alkanes smaller molecules are gases at room temperature, larger molecules tend to be liquids or soft solids; soluble in nonpolar solvents; generally unreactive

no functional groups; all C−C bonds are saturated

van der Waals forces

Alkenes smaller molecules are gases at room temperature, larger molecules tend to be liquids or soft solids; soluble in nonpolar solvents; undergo addition reactions

C=C van der Waals forces

Alkynes smaller molecules are gases at room temperature, larger molecules tend to be liquids or soft solids; soluble in nonpolar solvents; undergo addition reactions

C≡C van der Waals forces

Making Connections

13.

Common name Use

ethene ethylene reactant in the manufacture of antifreeze

propene propylene raw material in making plastic

ethyne acetylene fuel for welding torches


14. Methane is a major component of natural gas, and is used as fuel in homes for cooking and heating, and in schools for gas burners. Ethane is also a component of natural gas. Propane is a fuel used in gas barbecues. Butane is a fuel used in cigarette lighters. Pentane and hexane are used in dry-cleaning solvents, naphtha gas, and camping fuel. Pentane–decane are components of gasoline for cars. These alkanes are suitable for use as fuels because they all combust readily and their combustion reactions are highly exothermic.

15. Global warming refers to an observed increase in average global temperatures. Some scientists suggest that this effect is caused by the increase in concentrations of carbon dioxide in the atmosphere. Carbon dioxide gas seems to trap infrared radiation emitted and reflected by Earth. The cause of the increase in carbon dioxide levels may be the combustion of hydrocarbons, producing carbon dioxide and water.

16. When the lighter is “flicked,” the spark wheel rubs against the piece of flint, creating a spark. The spark ignites the butane gas coming out of the gas tank through the flame nozzle. The lighter cap must be open to have a flame. If the cap is closed, the flame is extinguished.

Extension

17. Student answers may vary. Hydrocarbons may form ring structures of several carbon atoms, some with double bonds. Two examples are 1,3-dimethylcyclopentane

and methylbenzene (more commonly called toluene), in which a methyl group is attached to a six-carbon ring structure with a unique arrangement of double bonds.


3.2 ACTIVITY: BUILDING MOLECULAR MODELS

(Page 192)

Observations

Sample Observation Table

Procedural step Name Formula Structural formula

2. butane C4H10

1-butene

3.

2-butene

C4H8

1-butyne

2-butyne

1,2-butadiene

4.

1,3-butadiene

C4H6

[Students are not expected to be able to name the alkenes with two double bonds because this nomenclature was not taught in the section.]


Synthesis

(c) (i) one (ii) three (iii) three (d) (i) There is no functional group for which we need to indicate a location.

(ii) The carbon chain should be numbered in the opposite direction to give the lowest number: 2-hexene. (iii) There can be no triple bond formed by a single carbon atom.

(e) A wooden stick is used to form the first bond in a multiple bond; the second or third bonds are formed by a spring, which more readily comes undone.

Extension

(f) Isomer: 1-hexene

3.3 FRACTIONAL DISTILLATION AND CRACKING

TRY THIS ACTIVITY: THE GREAT MARBLE RACE

(Page 193)

(a) The marbles travelled more slowly in the oils designed for summer, and more quickly in the oils designed for winter. We could conclude that the “summer” oils are thicker (more viscous) than the “winter” oils. When each oil was cooled in the ice bath, the marbles travelled more slowly in them than before cooling. Similarly, the marbles travelled more quickly in the warmed oils. Cooler oils appear to be more viscous than warmer oils.

An explanation for these observations is that the forces of attraction between the molecules in the summer oils were stronger than the forces of attraction between molecules in the winter oils. Also, when cooled, the molecules moved more slowly and were closer together, with stronger forces of attraction. The reverse is true for the warmed oils.

(b) In cold winter temperatures, motor oils become more viscous. Therefore, a less viscous oil is needed in winter in order to have the same viscosity as the summer oils.


(Page 196)


1. Petroleum is a complex mixture of hydrocarbon molecules, formed from prehistoric plants and animals. This mixture contains gases, liquids, and dissolved solids composed of many different hydrocarbon molecules, some of which may be up to 40 carbon atoms long. Some components are used as fuels for heat and cooking, dry-cleaning solvents, gasoline, kerosene and diesel fuel, furnace oil, heavy greases, waxes, cosmetics, polishes, and asphalt and tar for roofs and roads.

2. (a) The small hydrocarbons molecules, such as methane, ethane, propane, and butane, exist as gases. Larger hydrocarbons are liquids, and the largest molecules, with boiling points over 400°C, exist as solids. The smaller the molecule is, the lower the boiling point it has.

(b) In fractional distillation, the entire mixture of hydrocarbons is first heated to very high temperatureshigh enough to evaporate nearly all of the hydrocarbons, small and large. Then, the hot gases are allowed to rise in a tall fractionation tower. The upper parts of the tower are cooler than the lower parts. Each gas condenses at its own boiling point. As the hot gases travel up through the lower, warmer sections, the larger molecules

Jim

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condense. As the gases ascend higher, the smaller molecules also condense. As each fraction condenses, the liquid formed is collected on trays.

3. This fraction boils at 10°C; that is, it is a liquid below 10°C because it has not yet boiled, and is a gas above 10°C because it has already boiled. Therefore, it is a gas at 20°C.

4. Cracking is the process used to convert large straight-chain hydrocarbons into smaller branched-chain hydrocarbons, usually by heating with a catalyst. This process is important because one of the most valuable and profitable petroleum products is high-octane gasoline, which contains highly branched alkanes.

5. The approximate boiling point of propane is under 30°C, while waxes boil at over 450°C. The difference is due to intermolecular forces. As the length of the hydrocarbon molecules increases, the strength of the van der Waals forces between molecules increases as well, so more heat is required to pull the molecules apart. Therefore, higher temperatures are required to pull the molecules far enough apart to change the substance to a gas.

6. Student answer will vary. (a) propane in a gas barbecue; butane in a lighter (b) kerosene in a camping stove or lamp; lubricating oil for a bicycle chain (c) wax in candles; asphalt on roads

Applying Inquiry Skills

7. The mixture can be separated by distillation, using the apparatus shown. The distillation column allows the

evaporated gases to rise; the thermometer reads the temperature of the gases; the condenser, cooled by cold water, condenses the evaporated gases. The mixture is placed in the round-bottom flask and heated gently. The hydrocarbon with the lower boiling point will evaporate first, condense, and be collected. The temperature of the column will then rise until the boiling point of the other hydrocarbon is reached. At that point, the hydrocarbon with the higher boiling point will evaporate and be collected.


Making Connections

8. Canada exports approximately 60% of its crude oilmainly heavy crude oil from western Canada to the United States. Canada also imports light crude oil from the United States by pipeline, or from abroad by tankers. Canada’s northern territoriesYukon, Northwest Territories, and Nunavuthave large resources of crude oil. Exploration for crude oil also began in Atlantic Canada about 50 years ago, in Nova Scotia, Newfoundland, New Brunswick, and Prince Edward Island. Alberta remains the focus of the petroleum industry in Canada, producing 70% of the country’s crude oil. Crude oil is fractionated, and the collected components are used for fuel such as gasoline, jet fuel, kerosene, diesel oil, and for other purposes, such as lubricating oils, waxes, and asphalt.

9. Motor oils may contain viscosity improvers, anti-wear additives, anti-oxidants, anti-foam agents, and detergents to maintain engine cleanliness. 5W30 and 10W30 are the most commonly used motor oils. They are thin enough for cranking at low temperatures, and thick enough to lubricate satisfactorily at high temperatures. In warmer seasons, use more viscous motor oils (higher numbers). In colder seasons, use less viscous motor oils (lower numbers). The following motor oils are recommended for the lowest expected temperatures listed:

Lowest expected temperature

Type of motor oil Brand Cost

0°C 5W20, 5W30, 10W30, 10W40, 20W50

Under $4/L

–18°C 5W20, 5W30, 10W30, 10W40

Under $4/L

Below –18°C 5W20, 5W30 Under $4/L

10. In Canada, fossil fuels provide over 85% of our total energy use. These fuels, which include coal, crude oil, and natural gas, are formed over millions of years from long-dead plant and animal material. That is why they are called fossil fuels. There is a concern about their use because they are non-renewable: when we have exhausted the existing supply, there will be no more fossil fuels available. Another concern about the use of fossil fuels is that, when burned, these hydrocarbons produce carbon dioxidea product that may be partly responsible for global warming.

11. Student answers will vary. Possible answers include: home heating (service technician, furnace maintenance, air conditioning installation); furniture stripping and refinishing (repairs and restoration); hobby shopsplastic model cars and airplanes (salesperson); painting service (home painting and renovations); hot tubs and spas (service technician and installer); insulation contractors (installers and maintenance technicians); lamination products and services (service personnel); lawn maintenance (fertilizer application); automotive industry (oil changes and lubrication services); packaging services (materials supplier); plastic patio furniture supplier (retail staff); driveway sealing (asphalt sealing); photo finishing (film developing); pipe fabricating (factory staff); plastics (moulders); plumbing contractors (installers); recording services (sound and video technicians); refrigerators and freezers (technicians)

3.4 INVESTIGATION: SEPARATING A MIXTURE BY DISTILLATION

(Pages 197–198)

Prediction

(a) Substances with the lowest boiling point will be recovered first. Components will be recovered in the following order (from first to last): hexane, 2-methyl-2-propanol, and paraffin wax. The reasons for this order are that propanol contains an –OH group, which causes hydrogen bonding between molecules. Hydrogen bonds are stronger intermolecular forces than the van der Waals forces that exist between hexane molecules. Paraffin wax consists of much longer molecules than either hexane or propanol, and thus has stronger van der Waals forces than the other two hydrocarbons.


(b) Boiling points: hexane: 67.8°C 2-methyl-2-propanol: 82°C paraffin wax: 169°C

Analysis

(c) to (e)

The temperature remains at the boiling point of the first fraction until it has completely boiled off (arrow 1); then the temperature rises again. Bracket 2, over the second plateau, indicates the time over which the 2-methyl-2-propanol was boiling off and being collected. During this time, the temperature of the mixture remained constant.

(f) The boiling points are the temperature readings at the first and second plateaus: 68°C and 82°C.

Evaluation

(g) There may be a lag in time from the temperature readings graphed and the fractions collected in the flask because it may take time for the vapour to condense and to travel down the condenser. The graph may not show clear plateaus because the difference in boiling points may not be sufficient for a sharp separation. Suggested improvements include gentler, more even heating, and using a longer distillation column.

(h) Student answer may vary. Discrepancies may be due to impurities in the mixture, heating too rapidly, and sub-optimal apparatus (e.g., insufficient length of column).


3.5 FUNCTIONAL GROUPS

TRY THIS ACTIVITY: BENDING WATER

(Page 200)

(a) hexaneno functional groups alcoholhydroxyl group, –OH diethyl etheran oxygen atom bonded to two alkyl groups acetonea carbonyl group, C=O

(b) A stream of hexane does not bend because it has no polar groups that are attracted to (or repelled by) a charged object. The stream of alcohol bends because the –OH group is polar and is strongly attracted to (or repelled by) the charged object. The stream of diethyl ether does not bend, or only very slightly, because the oxygen atom bonded to two alkyl groups is only slightly polar, and thus is only slightly affected, if at all, by a charged object. The carbonyl group in acetone is a polar group and thus causes the acetone molecules to be attracted to (or repelled by) the charged object, so the stream of liquid bends.


(Page 201)


1. A functional group is a structural arrangement of atoms that, because of their electronegativity and bonding type, imparts particular characteristics to the molecule.

2. C=C and C�C bonds are more reactive than C–C bonds because the second and third bonds formed are weaker than the single bonds formed, and are thus more easily broken, making the multiple bonds more reactive.

3. In general, polar molecules have higher boiling points than less polar molecules because polar molecules have stronger intermolecular attractions that require more energy (higher temperatures) to overcome. Very large nonpolar molecules are affected by London dispersion forces that may cause their boiling points to be comparable to those of smaller polar molecules.

4. Functional groups can contain carbon–carbon multiple bonds, which are more reactive than single C–C bonds; single bonds between carbon and more electronegative atoms (e.g., O, N, or a halogen atom), which result in polar bonds and hydrogen bonding; and carbon double-bonded to oxygen, a highly polar bond.

5. (a) The –OH or –NH functional group raises the melting and boiling points of a compound because the increased polarity of the molecule increases intermolecular forces of attraction, requiring more energy to separate the molecules.

(b) The functional group increases the solubility in polar solvents because –OH and –NH groups allow increased hydrogen bonding with polar solvents.

6. (a) –OH group; high solubility in water (b) carbon–carbon double bond; low solubility in water (c) carbonyl group, C=O; high solubility in water (d) –OH group and carbonyl group, C=O; high solubility in water

7. (a) H2O, NH3, CH4 (b) Water and ammonia are mutually soluble, but methane is not soluble in the other two compounds. The

electronegativities of O, N, C, and H are 3.5, 3.0, 2.5, and 2.1, respectively. Thus, the O–H and N–H bonds in water and in ammonia are more polar than the C–H bonds in methane. The polar bonds in water and ammonia allow them to form hydrogen bonds. Thus, they are soluble in each other.

(c) All three compounds may be considered organic because they are produced by living organisms (e.g., water by animals and plants, ammonia and methane by bacteria). According to the chemical definition of “organic,” that is, containing carbon, only methane is organic.


3.6 EXPLORE AN ISSUE: THE COST OF YOUR COLD DRINK

Understanding the Issue

(Page 203)

1. A coolant repeatedly evaporates and condenses in the cooling coils. The coolant absorbs heat when it evaporates. This heat is extracted from the foods and drinks in the fridge, thus cooling them.

2. Ammonia, methyl chloride, and sulfur dioxide were used in the later 1800s. These substances are toxic. Freon was used in the 1920s. It is nontoxic and unreactive, but causes damage to the ozone layer in the upper atmosphere. Since the 1970s, HCFCs and HFCs have been used. Switching to these compounds may reduce environmental damage.

3. Propane (C3H8), butane (C4H10); since they do not contain halogens, they do not affect the ozone layer. 4. North American consumers prefer larger refrigerators and additional features, such as automatic defrost, that require

much larger quantities of coolant. North American manufacturers are also reluctant to abandon older technology in which they have invested time and money.

5. [Sample answer] Consumers can influence manufacturers’ decisions by writing to manufacturers, offering concerns and suggestions; organizing information sessions and inviting representatives from manufacturers; writing letters to newspapers; contacting politicians, such as government environmental agencies; informing retail outlets of their preference; and not buying products that do not meet consumers’ expectations.

Role Play: Choosing a Refrigerant

(Page 203)

(a) [Sample answer] One other way of measuring cost is the political cost. Local politicians have to think about what is best for their constituents, and what will help them get re-elected. Union reps must consider the political cost, for their union, of supporting one type of coolant over another. If choosing one type of coolant results in fewer fridges being sold, and therefore fewer being ordered and manufactured, the union members might be unhappy with the union reps who chose this course of action, and withdraw their support. If union reps support the most environmentally friendly option, union members might applaud their ethical stand, and support them politically.

(b) [Sample answer] As the local MP, I would be very anxious to bring well-paying jobs to my community. I would probably back the technology that would result in the most jobs, and ensure some stability for those jobs. If we could get a Greenfreeze research lab built in the area, as well as the manufacturing facility, we would have even more jobs. I would win support for helping to preserve the ozone layer. However, I would have to be confident that the Greenfreeze refrigerators would sell well, otherwise my constituents would be laid off from the factory. My popularity would decline and I might lose me my seat in office.

(d) [Sample answer] Points in favour of HFCs and HCFCs: proven technology, minimal changes for manufacturers to production lines, an improvement on the old CFCs, refrigerators are likely to be cheaper and to sell well, HFCs and HCFCs are nontoxic and inert, unlike the butane in Greenfreeze. Points in favour of Greenfreeze: even more ozone-friendly than HFCs and HCFCs, long-term health could improve, the technology already exists in Europe, North Americans would have environmentally friendly options when choosing a refrigerator, the publicity of introducing a new technology would help sales.

3.7 ALCOHOLS AND ETHERS

PRACTICE

(Page 206)

1. (a)

Jim

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Jim

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(b) (c) (d)

2. (a) 3-pentanol (b) 3-heptanol

TRY THIS ACTIVITY: BURNING PAPER

(Page 207)

(a) The paper remains unchanged, possibly because any heat generated by the burning alcohol is absorbed by the water and the alcohol as it evaporates. The paper never becomes hot enough to burn. The alcohol burns off, leaving only water, which extinguishes the flame.

CAREER CONNECTON: PHARMACY TECHNICIAN

(Page 207)

(i) Job description: responsible for preparing and packaging medications; maintains dispensing records for medications, supplies, and equipment; inspects medical areas; maintains storage standards.

Qualifications: secondary school diploma; strong science background; good math skills; knowledge of pharmacy terminology, medication names, and aseptic techniques; pharmacy technician program certification.

Salary: below-average hourly wage of about $13.67 (compared to national average of $16.91). (ii) [Sample answer]

Human Resources Department North-Western Hospital Pine Valley, Ontario

Dear Sir/Madam:

I am writing in response to your advertisement for a Pharmacy Technician, posted in the Pine Valley Examiner on Saturday, 29 February. I am very interested in that position. I have recently graduated with excellent marks from Mohawk College’s two-year Pharmacy Technician Program. I also have good “people skills,” and enjoy working in a team.

My resume is attached, with all my contact information.

I look forward to hearing from you to arrange an interview.



(Page 208)


1. The presence of a hydroxyl group in methanol makes the molecule more polar than methane, and allows hydrogen bonding between molecules. Hydrogen bonding results in a higher boiling point for methanol.

2. (a)

(b)

3. In 4-hexanol, the –OH group is on carbon atom 4, on a six-carbon backbone. The carbon chain should be numbered in the opposite direction to give the lowest possible number for the functional group. The correct name is 3-hexanol.

4. butane, 1-butanol, octane, 1-octanol (lowest to highest boiling point) 5. (a) C2H5OH + 3 O2 → 2 CO2 + 3 H2O

(b) 2 CH3CH(OH)CH3 + 9 O2 → 6 CO2 + 8 H2O 6. (a) Ethoxypropane will evaporate at a lower temperature because, unlike 1-pentanol, it does not have a polar –OH

group. (b) Ethoxypropane has a higher solubility in a nonpolar solvent because it is less polar than 1-pentanol.


Front:

Examples Family name and general formula IUPAC name Common name Structural formula

Alcohols

R−OH

2-butanol none

Ethers

R−O−R

ethoxypropane none

Back:



Alcohols soluble in water and some nonpolar solvents; react with carboxylic acids to form esters

hydroxyl group hydrogen bonds, van der Waals forces

Ethers soluble in nonpolar solvents oxygen atom bonded to two alkyl groups



8. Glycerol is an alcohol with a three-carbon chain, and a hydroxyl group on each carbon atom. The extra hydroxyl groups form extra hydrogen bonds with water, which results in extra water molecules being held to the glycerol molecules, keeping the water from freezing.

Making Connections

9. (a) IUPAC name: 1,2-dihydroxyethane (b) Uses: most commonly used as an antifreeze, but also has many other product applications, including polyester

resin (PET), film and fibres, and heat transfer and hydraulic fluids. (c) Properties: clear, colourless, odourless, viscous liquid with a sweet taste. Properties are a result of the two –OH

groups (sweetness) and the formation of hydrogen bonds (a viscous liquid with a fairly high melting point and boiling point).

3.8 INVESTIGATION: PROPERTIES OF ALCOHOLS

PART 1: TRENDS IN PROPERTIES OF ALCOHOLS

(Pages 209–210)

Prediction

(a) Order of increasing melting points and boiling points: ethanol, 1-propanol, 1-butanol Solubility in mineral oil (nonpolar solvent) and water (polar solvent): All three compounds are similarly soluble in polar solvents and very slightly soluble in nonpolar solvents. Acidity: All three alcohols are basic (blue in litmus).

Hypothesis

(b) Melting point and boiling point: Each alcohol has a single hydroxyl group, so each one has similar hydrogen-bonding capabilities. The increasing size of the molecules increases the strength of the van der Waals forces, thus increasing the melting and boiling points. Solubility: Since each alcohol has a single hydroxyl group, each one will be similarly soluble in polar solvents. Since they have small alkyl groups, they will be only slightly soluble, if at all, in nonpolar solvents. Acidity: All three alcohols will also have similar basic properties due to the single hydroxyl group.

Observations

(c) and (d)

Property Ethanol 1-Propanol 1-Butanol

structural formula

melting point –117ºC –126ºC –89ºC

boiling point 78ºC 97ºC 117ºC

solubility in mineral oil

slightly soluble slightly soluble slightly soluble

solubility in water soluble soluble soluble

colour with litmus blue blue blue


Analysis

(e) Melting points and boiling points, from lowest to highest, are: ethanol, 1-propanol, 1-butanol Solubility in nonpolar and polar solvents: All three alcohols are similarly soluble in polar solvents and very slightly soluble in nonpolar solvents. Acidity: All three alcohols turn blue in litmus.

(f) The observations agree with our predictions. Reasons are as follows: • The increasing size of the molecules increases the strength of the van der Waals forces, thus increasing the

melting and boiling points. • Since each alcohol has a single hydroxyl group, each will be similarly soluble in polar solvents. Since they have

small alkyl groups, they will be only slightly soluble, if at all, in nonpolar solvents. • All three alcohols will also have similar basic properties due to the single hydroxyl group.

Synthesis

(g) Boiling points 1-butanol: 118°C 2-methyl-2-propanol: 83°C 1-hexanol: 157°C 2,2-dimethyl butanol: 121°C Trends: the straight-chain alcohols have higher boiling points than branched-chain alcohols of similar molar mass because there are more van der Waals forces of attraction between longer chains than between more spherically shaped molecules of similar molar mass. Of the straight-chain alcohols, longer-chain molecules have higher boiling points than shorter-chain alcohols because there are more van der Waals forces of attraction between longer chains than between shorter chains.

(h) Linear molecules have more surface area, and therefore more intermolecular forces, than do spherical molecules; therefore linear molecules have higher boiling points than spherical molecules of similar size.

PART 2: ALCOHOL AND ALKANE COMBUSTION

(Pages 210–211)

Prediction

(i) In the combustion of both ethanol and hexane, the products will be carbon dioxide and water.

Observations

(j) and (k)

Property Ethanol Hexane

structural formula

organic family alcohol alkane

cobalt chloride test positive positive

limewater test positive positive

Analysis

(l) The positive cobalt chloride test indicates that water is produced by both reactions. The positive limewater test indicates that carbon dioxide is produced by both reactions. C2H5OH + 3 O2 → 2 CO2 + 3 H2O 2 C6H14 + 19 O2 → 12 CO2 + 14 H2O

(m) Oxygen in the air must be allowed to enter the beaker to enable combustion to continue.


Synthesis

(n) The wick burns at a higher temperature than ethanol and hexane, and thus will not burn until all the liquid has completely burned and the heat is used to evaporate the fuel.

(o) The products in both reactions are the same. Alcohols are liquids and are more easily transported and stored than the smaller hydrocarbons, which are generally gases. Gases must be compressed into liquids for storage. Compressed gases are dangerous.

3.9 ALDEHYDES AND KETONES

TRY THIS ACTIVITY: WHERE’S THE CUP?

(Page 213)

(a) The bottom of the Styrofoam cup “disappears” as it is dissolved by the acetone. (b) The IUPAC name for acetone is propanone. Acetone is polar due to its carbonyl group, and also nonpolar due to its

alkyl groups. This characteristic makes acetone miscible with both polar and nonpolar substances. (c) Since Styrofoam dissolved in acetone, it probably has both polar and nonpolar characteristics.


(Pages 213–214)


1. In order of increasing boiling points: B, A, C. This order is predicted because A (1-propanone) contains a carbonyl group (with a polar double bond), making it more polar than B (propane), which gives A a higher boiling point than B. C (1-propanol) contains a hydroxyl group, which can hydrogen bond with other molecules, giving C a higher boiling point than A or B.

2. In increasing order of solubility: C, A, B. C (butane) is a nonpolar hydrocarbon and is less soluble in water than A (the ketone) and B (the alcohol). A has a polar carbonyl group, making it more soluble in water than C, but it is less soluble than B, which has a hydroxyl group that allows it to hydrogen bond.

3. (a)

(b)

(c) Organic family Functional group alcohol hydroxyl group ether oxygen bonded to two alkyl groups aldehyde carbonyl group at the end of the carbon chain ketone carbonyl group in the interior of the carbon chain



Front:


Aldehydes R−CHO

ethanal acetaldehyde

Ketones

R-C(O)−R

propanone acetone

Back:



Aldehydes boiling points intermediate between hydrocarbons and alcohols of similar size; soluble in polar and nonpolar solvents

carbonyl group at end of carbon chain

van der Waals forces; no hydrogen bonding but highly polar carbonyl group produces strong intermolecular forces

Ketones boiling points intermediate between hydrocarbons and alcohols of similar size; soluble in polar and nonpolar solvents

carbonyl group in interior of carbon chain


Making Connections

5. Examples include acetone, wood alcohol, rubbing alcohol, formaldehyde, natural gas, barbecue gas, lighter fluid, and glycerin.

6. (a) methanal (b) Formaldehyde is a flammable, poisonous, colourless gas with a suffocating odour. It readily polymerizes into

paraformaldehyde, a white solid that can be formed into candles and used for fumigating rooms. Formalin, the preservative used in biological materials, is a solution of formaldehyde in water, with a small amount of methanol added.

Other fluids used as preservatives include alcohol (the standard is 70–75% ethanol, or 40–50% 2-propanol); Zenker’s fluid (containing mercury(II) chloride, glacial acetic acid, potassium dichromate, and sodium sulfate in water).

7. [Sample Answer] Several chemists wanted to test the effect of pheromones on humans. They placed small samples of male human pheromones under the chair seats of a number of chairs in a lecture hall just before the audience was allowed in. Members of the audience were free to sit where they chose. As the chemists had predicted, each of the “pheromone” seats was selected by a female. What are the odds of that? There are reportedly colognes and perfumes available that contain potent concentrations of human pheromones, instead of the usual extracts of flowers and fruits, which are better designed to attract insects and birds.


3.10 SAFE USE OF ORGANIC SOLVENTS

CAREER CONNECTION: FIREFIGHTERS

(Page 217)

(i) Pre-services courses are available in many communities in Ontario, mostly in community colleges (such as Northern College in Timmins, Ontario). These courses can be taken on a part-time or full-time basis. Only after completing this course would a candidate be considered for hiring by the various fire departments in Ontario. When hired, the new firefighter is sent to the Ontario Fire College, in Gravenhurst, Ontario, to take the necessary courses to become a qualified firefighter. (NOC code 6262)

(ii) The average wage for a new firefighter is $11.98 an hour (compared with the national average, for people of a similar age, of $11.09). This wage advantage increases with experience, with a firefighter’s average hourly wage being over $23 (national average about $17). Also, the unemployment rate for firefighters is below the national average.


(Page 217)

Understanding Concepts 1. Flammable liquids readily ignite and burn at normal working temperatures. Combustible liquids ignite and burn at

higher temperatures. 2. Student answers will vary.

Organic solvent Use Storage location

mineral spirits paint thinners garage

propanone (acetone) nail polish remover bedroom

2-propanol rubbing alcohol medicine cabinet in bathroom

tetrachloroethene (perchloroethylene), C2Cl4

stain remover laundry room

Organic solvents should be stored away from other chemicals, in well-ventilated spaces and away from sunlight or heat sources. They should not be stored in a basement or other below-ground locations. Organic solvents should not be used close to heat sources or open flames, and only minimum required quantities should be transferred.

3. It means that, at –9°C, enough liquid solvent will vaporize and mix with air to form a mixture that will burn.

Applying Inquiry Skills 4. Use only the minimum amount needed. Return any unused ethanol to the proper storage container. Keep in a covered

container to reduce evaporation. Keep away from sunlight and other heat sources. Do not use near open flames or electrical appliances that may produce a spark. Use in a well-ventilated area or in a fume hood. Avoid inhaling vapours. Dispose of waste ethanol through hazardous waste collection.

Making Connections 5. Student answers will vary.

• No food or drink of any kind is allowed in a laboratory at any time. • No open-toed shoes are allowed in the laboratory. Long hair and loose clothing must be tied back. • Safety equipment, such as eye protection and lab aprons, must be worn as directed. • Each laboratory is equipped with an eyewash station, a shower, fire extinguishers, fire blankets, and fume hood.

The locations of these items are clearly displayed. • Material Safety Data Sheets are made available for all chemicals used or stored in the school. • A ventilation system for the laboratory is required, and chemical storage cabinets for organic solvents and

oxidizing agents must be ventilated to the outside. • A school emergency response team is in place to handle any hazardous situations. • A hazardous waste disposal system is in place.

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6. Student answers will vary, but should include the following recommendations. • Carefully read and follow the recommendations on the MSDS for every chemical substance that you use. • Be aware of the flammability and combustibility of solvents. • Use organic solvents in a well-ventilated location, such as outdoors or a room with open windows, away from

ignition sources such as electrical sparks, open flames, and hot surfaces. • Do not store organic solvents in direct sunlight, near heat sources, or in basements. • Return any unused portions of solvents immediately to the appropriate storage containers. • Dispose of waste solvents according to environmental restrictions; never pour them down the sink. • Some solvents will spontaneously combust; for example, rags soaked in motor oil or linseed oil will ignite if they

are stuffed in a container such as a plastic pail. The rags should be hung outside on a clothesline, to allow any heat that is produced to dissipate safely.

• Do not inhale any solvents.

3.11 CARBOXYLIC ACIDS

TRY THIS ACTIVITY: MAKING A BATH BOMB

(9)

(a) citric acid + sodium hydrogen carbonate → sodium citrate + carbon dioxide + water


(Page 220)


1. (a) (b) The hydroxyl group in this functional group is polar and can hydrogen bond, making the molecule soluble in

water. The carbonyl group is also polar and, with the hydroxyl group, increases intermolecular attractions and thus raises the melting and boiling points of carboxylic acids.

2. Carboxylic acids contain the carboxyl group, which consists of a carbonyl group and a hydroxyl group. Both carbonyl groups and hydroxyl groups are polar groups, resulting in carboxylic acids being polar molecules.

3. (a)

ethanoic acid

oxalic acid

(b) Oxalic acid is a solid at room temperature because, as it is polar, the van der Waals forces between the molecules are stronger than those in ethanoic acid (vinegar). There is also more opportunity for hydrogen bonding among molecules.

4. The gas (A) has the lowest boiling point and must be an alkane, the least polar molecule. The liquid (B) has the next highest boiling point and must be the alcohol, which has a hydroxyl group.

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5. Student examples will vary.

Front:



Carboxylic acids

R−COOH

ethanoic acid acetic acid (vinegar)

Back:



Carboxylic acids soluble in water, turn litmus pink, react with alcohols to form esters

carboxyl group

−COOH

hydrogen bonds, van der Waals forces

6.


7. Melting and boiling points: The ketone is more likely a liquid at room temperature, while the carboxylic acid is more likely a solid. The carboxyl group in the acid is polar and also can hydrogen bond, while the ketone does not contain the hydroxyl group. Litmus and pH test: Carboxylic acids turn litmus red, an acidic pH.

3.12 INVESTIGATION: PROPERTIES OF CARBOXYLIC ACIDS

(Pages 221–222)

Prediction

a) [Sample answer] Stearic acid has a much longer hydrocarbon chain than does acetic acid. Thus, stearic acid is more nonpolar than acetic acid and will be less soluble in a polar solvent such as water, and more soluble in a nonpolar solvent such as vegetable oil. Stearic acid will also have a higher melting point because its long hydrocarbon chain allows intermolecular forces of attraction (van der Waals forces). Acetic acid will react readily with the basic solution, but stearic acid will react less readily because it is less soluble in the aqueous solution of the base.


Observations

(b) to (e)

Table 1 Properties of Carboxylic Acids

Property Acetic acid Stearic acid

structural formula

molar mass 60.05 g/mol 284.50 g/mol

melting point 16.7ºC 69ºC

boiling point 118ºC 383ºC

solubility in water soluble in water

low solubility in water

solubility in vegetable oil

low solubility in vegetable oil soluble in vegetable oil

reaction with base

reacts with base does not readily react with base

Analysis

(f) Both acids contain the polar carboxyl group. In addition, stearic acid has a long hydrocarbon group with stronger van der Waals attractions than in the shorter ethanoic acid. For this reason, stearic acid has a higher melting point and boiling point than ethanoic acid.

(g) Acetic acid is more soluble in water than is stearic acid, and less soluble in oil. Stearic acid, with its long hydrocarbon component, has a longer nonpolar component and is thus more soluble in the nonpolar oil.

(h) Acetic acid reacts with sodium hydrogen carbonate, as acids do. Stearic acid is not soluble in water and does not show a reaction with aqueous sodium hydrogen carbonate.

Evaluation

(i) [Sample answer] Yes, the Procedure allowed the collection of appropriate evidence regarding all aspects of this investigation, except for the reaction with sodium hydrogen carbonate. Since stearic acid was not highly soluble in water, it is inconclusive whether it reacts with sodium hydrogen carbonate.

(j) [Sample answer] Answers obtained in the Analysis are in agreement with the Prediction. The theoretical model of carboxylic acids helped to predict the chemical properties of these acids. The effect of the polar and nonpolar components of each acid could be used to predict physical and chemical properties of the compounds.

3.13 ESTERS


(Page 225)


1. An ester contains an –OR group in place of the –OH group in the carboxylic acid. Both carboxylic acids and esters contain a carbonyl group.


2. Carboxylic acids contain a carbonyl group and a hydroxyl group (together making up the carboxyl group). Esters also contain a carbonyl group, but not the hydroxyl group. Since both groups contribute to the polarity of the molecule, esters are less polar than are carboxylic acids, and are therefore less soluble in water.

3. In esterification, an organic acid and an alcohol react to produce an ester and water. In the reaction between the inorganic acid HCl and the inorganic base NaOH, a salt, NaCl, and water are produced. Thus, an esterification is similar to a neutralization reaction between inorganic acids and bases.

4. A hydrolysis reaction is a reaction in which a bond is broken by the addition of the components of water, forming two or more products. An ester can undergo a hydrolysis reaction to form an acid and an alcohol. It may be considered the reverse of an esterification reaction.


Front:


Esters R–COO–R

methyl propanoate (none)

Back:



Esters less soluble in water than their parent acids; lower melting and boiling points than parent acids; not acidic; often have distinctive odours, e.g., fruity, peppermint.

R–COO–R van der Waals forces

Applying Inquiry Skills 6. Students should give three suggestions.

(i) Test each liquid with litmus. The carboxylic acid will turn blue litmus pink, while the ester will not. (ii) Add water to each liquid. The carboxylic acid dissolves readily in water, while the ester dissolves less readily. (iii) Determine the boiling point of each liquid by heating gently in a fume hood until it starts to boil. The carboxylic

acid has a higher boiling point than does the ester. (iv) Carefully waft each liquid to detect any odour. Esters generally have distinctive odours.

Making Connections

7. (a)


(b) Animal hides decompose quickly unless they are cured to remove the water from the skin. The hide is first soaked in water to remove water-soluble substances. Hair is removed by soaking the hide in a mixture of lime and water, followed by an enzyme mixture. The hair and any remaining tissue is removed by machine, and the hide is washed and treated with tannic acid. The tannic acid displaces water from the spaces between the hide’s protein fibres, allowing the fibres to cement together to form strong water-resistant leather.

3.14 ACTIVITY: SYNTHESIS OF ESTERS

(Pages 226–227)

Analysis

(a) Table 2 Summary of Condensation Reactions

Reaction 1 Reaction 2 Reaction 3

IUPAC name of alcohol used ethanol 2-propanol 1-pentanol

Structural formula of alcohol used CH3CH2OH CH3CH(OH)CH3 CH3CH2CH2CH2CH2OH

IUPAC name of carboxylic acid used ethanoic acid ethanoic acid ethanoic acid

Structural formula of

carboxylic acid used

CH3COOH CH3COOH CH3COOH

IUPAC name of ester produced ethyl ethanoate isopropyl ethanoate pentyl ethanoate

Structural formula of ester produced CH3COOCH2CH3 CH3COOCHCH3CH3 CH3COOCH2CH2CH2CH2CH3

Odour of ester produced fruity fruity banana

(b)

(c) The concentrated sulfuric acid acts as a catalyst. (d) The esters are insoluble in aqueous solution because each ester formed a layer on top of the cold water in the

evaporating dish. This effect is caused by the loss of the hydroxyl group from the carboxyl group when the ester bond is formed. Thus, the ability to hydrogen bond with water is lost.

Reaction in Tube #1

Reaction in Tube #2

Reaction in Tube #3


3.15 AMINES AND AMIDES


(Page 230)


1. An –OH group is removed from the carboxylic acid and an –H is removed from the amide to produce a water molecule.

2. Amines contain –NH groups, which are less polar than –OH groups in alcohols, and are less capable of hydrogen bonding than are –OH groups, which accounts for the lower boiling points of amines.

3. (a) amine (b) amide

4. (a) alcohol, amine; The –OH group in alcohols is more polar than the –NH group in amines, making alcohols less soluble in nonpolar solvents than amines.

(b) hydrocarbon, amine; Bonds between N and C are more polar than bonds between H and C. Therefore, amines are slightly more polar than hydrocarbons, making them less soluble in nonpolar solvents. However, if the nonpolar groups are large, the increased attraction between nonpolar groups may make amines more soluble in nonpolar solvents.

5. Length of nonpolar hydrocarbon component: CH3CH2CH2CH2CH3 Presence of double or triple bonds: CH2=CH2, CH3C�CCH3 –OH groups: CH3CH2OH –NH groups: H2NCH3 C=O bonds: CH3CHO, CH3COOH


Front:



Amines

1-aminopropane (none)

Amides

ethanamide (none)

Back:



Amines often have unpleasant odours; react with carboxylic acids to form amides; have higher boiling points and melting points than similar-sized hydrocarbons, lower boiling points and melting points than similar-sized alcohols; smaller amines are readily soluble in water

Hydrogen bonds due to any –NH groups; van der Waals forces due to polar C–N bonds

Amides generally insoluble in water

Hydrogen bonding due to –NH groups


7. (a) Each small unit must contain an amino group and a carboxyl group, so that an amide bond can form between small units.

(b) Because they have both amino groups and carboxyl groups, amino acids are likely fairly soluble in water and are capable of forming strong amide bonds.

Making Connections 8. The carboxylic acids, such as citric acid in lemons and acetic acid in vinegar, react with the amines responsible for

the fishy taste in fish to produce amides, thereby reducing the smell. For example,

3.16 EXPLORE AN ISSUE: REGULAR OR DIET?

Understanding the Issue

(Page 232)

1. cyclamates, saccharin, aspartame 2. (a) People who are trying to reduce their food energy intake, or who are living with diabetes, can still enjoy

sweetened drinks and foods. Also, artificially sweetened products do not contribute to tooth decay. (b) People who use artificial sweeteners are not avoiding highly sweetened foods and drinks, so are likely to

continue to consume them, whether sweetened naturally or artificially. Consuming sweetened foods may lead to continued weight gain and tooth decay. Furthermore, studies indicate that artificial sweeteners may be bad for your health.

3. (a)

Maspartame = 294.34 g/mol (b) Maspartame = 294.34 g/mol The portion in the aspartame molecule attributable to methanol is CH3O. mCH

3O = 31.04 g

%CH3O =

%CH3O = 10.55% (c) mCH

3OH =

=

mCH3

OH = 21.8 mg

31.04 g 100%

294.34 g/mol×

3200 mg ��

� �

�×

32.05 g/mol200 mg

294.34 g/mol×

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(d) LD50(70 kg) = 0.07 g/kg � 70 kg LD50(70 kg) = 4.9 g = 4900 mg (e) number of cans of diet pop =

= 220 cans

TAKE A STAND: HEALTH BENEFIT OR HEALTH HAZARD?

(Page 232)

(a) Student answers will vary. Aspartame: Reasons for its use: reducing caloric intake, to counter obesity; for sugar-reduced or sugar-free diets, e.g., for diabetic patients; to reduce incidence of tooth-decay

(b) Student answers will vary. Factors to consider: experimental design, e.g., use of controlled variables; type of system tested, e.g., tests done on mice, and the information transferred to human applications; size of population tested; number of independent research groups reporting findings; funding of the research group, e.g., whether the research is funded by the manufacturer of the product.

(c) [Sample answer] Risks are still uncertain and debatable. In some cases, benefits outweigh the risks, as in sugar-free diets prescribed by doctors. In other cases, any possible risk should be reduced by minimizing the daily use of aspartame.

3.17 ACTIVITY: CLASSIFYING PLASTICS

(Pages 233–236)

Observations (a)

Table 2 Summary of Observations and Possible SPI Codes (sample answer)

Sample tested

Density Flame colour

Acetone Melting Possible SPI code

1 floats in water, in alcohol solution, and in corn oil

code 5: PP

2 floats in water and in alcohol solution, and sinks in corn oil

code 4: LDPE

3 floats in water, and sinks in alcohol solution

code 2: HDPE

4 sinks in water green code 3: PVC

5 sinks in water not green increased softness in acetone

code 6: PS

6 sinks in water not green no increased softness in acetone

increased softness in boiling water

code 1: PETE

Analysis (b) Part 1

In water: Samples that float may be resin codes 2, 4, or 5 (less dense than water, whose density is 1 g/mL). Samples that sink may be resin codes 1, 3, or 6.

In alcohol solution: Samples that float may be resin codes 4 or 5 (less dense than alcohol solution). Samples that sink may be resin code 2.

In oil: Samples that float may be resin code 5 (less dense than resins 4 and 5). Samples that sink may be resin code 4. Part 2 Flame test: Of possible resin codes 1, 3, or 6, resin code 3 contains chlorine atoms. The sample that produces a green flame is resin code 3.

4900 mg

21.8 mg/can

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Part 3 Acetone test: Of possible resin codes 1 or 6, resin code 6 softens in acetone. The samples that soften in acetone are resin code 6. The samples that did not soften may be resin code 1. Part 4 Melting test: This sample may have resin code 1. If the sample softens in boiling water, it has resin code 1.

Evaluation

(c) [Sample answer] Repeat the procedure using known resin samples, codes 1 to 6, to confirm test results.

Synthesis

(d) Student answers will vary. Recycling operation at school • Types of materials collected: paper, plastic water bottles, plastic pop bottles, glass drink bottles, aluminum cans • Amounts: approximately four large garbage bags of paper each week, five large garbage bags of each type of

bottle and cans each week • Participation rate: approximately 30% of students recycle • Problems encountered: “recycling containers” do not keep bottles and cans separate, so bottles and cans need to

be sorted by hand; collection containers also contain garbage, sometimes making collected materials unusable • Destination: collected by city recycling facility; some items are destined for sorting locally, and some items are

transported to a large city nearby (e) Issues related to use of plastics:

• There is a growing demand for petroleum as raw materials for the manufacture of plastics. • Petroleum, a fossil fuel, is a non-renewable resource that cannot be replaced when the source is exhausted. • Most plastic products are non-biodegradable; that is, these products, when discarded, occupy large areas of land

for an indefinite length of time. Since they do not decompose, the atoms and molecules in plastics are not returned to the environment to be used in other systems.

Suggestions for non-synthetic substitutes: • cotton fibres instead of polyester • reusable metal cutlery instead of plastic • washable glasses instead of Styrofoam cups • washable cloth diapers instead of disposable synthetic polymers

(f) Student answers will vary. Posters should show types of recycled products, flow charts of recycling resources, benefits to environment, location and dates of collections.

(g) Student answers will vary. • PET: 56% of recycled PET is made into fibre for carpet and clothing, 13% into strapping, and 14% into food or

non-food containers. • HDPE: 29% of recycled HDPE (mostly from bottles) is made into new bottles. HDPE is also recycled into lawn

and garden products, such as flowerbed edging, and into plastic lumber for use in decks, benches, and picnic tables.

(h) Student answers will vary, but may include one of the following careers: recycling truck driver, planner for recycling routes, organizer of recycling facility. Other related fields include environmental enforcement, policy and planning, community relations, and other support services. Qualifications and training to be a waste systems manager: • an understanding of environmental issues • a background in environmental studies or waste management, or a degree in public administration • courses or qualifications in finance

3.18 POLYMERS

TRY THIS ACTIVITY: SKEWERING BALLOONS

(Page 238)

(a) The intermolecular attractions between polymer chains allow the long molecules to move aside to allow the skewer to push through without breaking, analogous to the noodles moving over each other.



(Page 242)

Understanding Concepts 1. carbon–carbon double or triple bonds 2. (a) intermolecular forces: van der Waals forces, electrostatic attractions due to any substituted groups present, and,

if crosslinking occurs, covalent bonds. (b) Properties of the plastics can be designed and controlled by the type of monomer used, and the type of bonding

present in the polymer. The polymers are stronger than the monomers, and can be moulded by various processes, depending on the degree of crosslinking.

(c) The double bonds in the monomers are replaced by single bonds in the polymers, resulting in the polymer having properties more similar to the less reactive alkanes than to the alkenes of the monomers.

3. The monomer must have more than one double bond for crosslinking to occur between polymer chains (e.g., 1,3-pentadiene).

CH2=CHCH=CHCH3 4. Two functional groups that can undergo condensation reactions, e.g., a carboxyl group, and either a hydroxyl group

or an amino group, must be present in the monomer of a condensation polymer. 5. Covalent bonding occurs within a polyamide chain. Van de Waals forces, and hydrogen bonding if N–H bonds are

present, occur between polyamide chains. 6. (a) Plastics are typically flexible, lightweight, mouldable, and electrically nonconductive. Plastics also soften when

heated. (b) Within long polymer molecules, you would expect to find covalent bonds. Intermolecular bonds are van der

Waals forces. Covalent bonds between molecules would exist if crosslinking were present. (c) Intramolecular bonding: The prevalence of single, rather than multiple, carbon–carbon bonds makes plastics

strong and chemically unreactive. Intermolecular bonding: Intermolecular forces and crosslinking make plastics strong, flexible, and mouldable. The more crosslinks there are, the more rigid the plastic is.

7. A polyester is linked by functional groups that form esters: carboxyl groups and hydroxyl groups (e.g., polyester). A polyamide is linked by functional groups that form amides: carboxyl groups and amino groups (e.g., nylon).

8. (a) Covalent bonds: intrachain bonds joining C, H, O, and N atoms. (b) Amide bonds: the linkage between the N of the amino group of the amine and the C of the carbonyl group of the

acid. (c) Hydrogen bonds: interchain attractions between –NH groups and carbonyl groups.

Making Connections 9. (a) HOOC−CH2CH2CH2CH2−COOH + H2N−CH2CH2CH2CH2CH2CH2−NH2

→ −OC−CH2CH2CH2CH2−CONH−CH2CH2CH2CH2CH2CH2−NH− (b) The numbers refer to the number of carbon atoms in the monomers. Nylon 6,6 refers to 6 carbon atoms in each

of the two monomers used.

Applying Inquiry Skills 10. (a) An ideal polymer would be able to absorb sufficient water to sustain a plant for several weeks, absorb nutrients

dissolved in water, would not be harmful to plants, and could be tailored to specific types of applications (e.g., houseplants, outdoor plants). Also, ideal polymers would degrade after several months into harmless products, and would be inexpensive.

(b) To test for absorption, place samples of equal mass of each polymer in equal volumes of excess water and excess water with dissolved nutrients. Determine the mass of liquid absorbed. To test for the release of liquid, mix equal swelled masses of each polymer with equal masses of a variety of soil types, and measure the moisture content over a test period. Store the mixture samples over several months and determine the amount of degradation. As a safety precaution, test pH. An appropriate test period would be two weeks.

Sample answer: (i)

Polymer Mass of polymer Mass of water added

Mass of polymer and absorbed water

polymer A 50.0 g 100.0 g 70.0 g

polymer B 50.0 g 100.0 g 80.0 g


(ii)

Polymer Mass of nutrient solution absorbed

% change in concentration of nutrients in excess solution

polymer A 50.0 g 100.0 g

polymer B 50.0 g 100.0 g

(iii)

Polymer Mass before degradation

Mass after degradation (8 weeks) pH

polymer A 50.0 g 25.0 g pH 5.5

polymer B 50.0 g 40.0 g pH 6.5

Analysis

Polymer A absorbed less fluid than polymer B, and did not absorb nutrients as well as polymer B. Polymer A also degraded to produce acidic substances. Polymer B allowed all nutrients to be absorbed but did not degrade as quickly as polymer A. 11. (a) [Sample answer] The following types of plastic products are accepted: code 1 (bottles for carbonated drinks,

containers for peanut butter, salad dressings); code 2 (milk cartons, water bottles, juice bottles, grocery bags); code 4 (dry-cleaning and grocery bags, flexible containers and lids); code 5 (ketchup bottles, margarine containers); code 6 (meat trays, plastic knives, spoons, forks). Code 3 is not accepted by municipal recyclings services because these items are too large for pickup or contain medical hazards in medical tubing, etc. Some construction pipes, siding, window frames, etc., are accepted by nonprofit environmental programs. Students will need to check their local recycling program for specific information. Table headings: SPI resin code; Type of products; Properties; Accepted by Municipal Recycling Organization; Accepted by Other Recycling Organization.

(b) and (c)

Common name of plastic

Monomer Molecular structure

vinyl ethene [–CH2–CH2–CH2–CH2–]n

Saran wrap 1,1-dichloroethene [–CH2–CCl2–CH2–CCl2–]n

acrylic CH2=CH–CN [–CH2–CH(CN)–CH2–C(CN)–]n

polystyrene styrene [–CH2–CH(Ø)–CH2–C(Ø)–]n

Polyvinylchloride (PVC)

chloroethene [–CH2–CHCl–CH2–CHCl–]n

12. (a) [Sample answer] Strong, flexible, chemically unreactive, insoluble in polar and nonpolar solvents, not softened by heat, nonbiodegradable

(b) [Sample answer] Presence of F or Cl atoms, controlled degree of crosslinking to obtain desired flexibility and strength, resistance to heat

13. Natural rubber is produced from the sap of the rubber tree, Hevea brasiliensis. The sap is collected, exposed to air, and gently heated. Natural rubber is a polymer of 2-methyl-1,3-butadiene (isoprene), CH2=C(CH3)–CH=CH2. The polymerization reaction is nCH2=C(CH3)–CH=CH2 → –[CH2–C(CH3)=CH–CH2]n–

Charles Goodyear developed the vulcanizing process in which rubber is heated with sulfur. This process produced a more reactive and stable rubber and made it suitable for a wide range of products, such as cushions, mattresses, raincoats, and shoes. Rubber is primarily used in car tires. A filler, such as carbon black, is added for reinforcement. Synthetic rubber was developed and produced in Germany during the First World War, and demand for materials increased research and production of new synthetic rubbers during the Second World War.

14. [Sample answers] This polymer would also be useful as a potting soil additive for moisture retention, as a filter for removing traces of moisture from gasoline and oil, as a time-release drug delivery system, and as material for “grow a dinosaur” type toys.


3.19 TECH CONNECT: THE NICOTINE PATCH


(Page 243)

Understanding Concepts 1. (a) Because the skin has both water-soluble (polar) and fat-soluble (nonpolar) components, any drug molecule that

travels through the skin must be a suitable size and must be soluble in both polar and nonpolar solvents. (b) The carbon rings and the methyl group are the nonpolar components of the nicotine molecule. The nitrogen

atoms are more electronegative than the carbon atoms, and thus provide a polar portion of the molecule. Thus, nicotine has both polar and nonpolar characteristics, and its size is sufficiently small to allow it to travel through the skin.

Making Connections 2. [Sample answer] Drug delivery systems, e.g., nicotine patches, estrogen patches.

Problem to be solved: Patients quitting smoking need a bridging program to relieve withdrawal from nicotine. Patients require estrogen to relieve symptoms of menopause due to surgery. Existing solution: nicotine gum, estrogen capsules. Problems: Patients may forget to take medication. As well, a low but continuous dosage is most effective. Improved solution: Polymers could be used to provide an adhesive patch on the skin, allowing the nicotine or estrogen to be absorbed through the skin on a continuous basis.

3. Student answers will vary. The Estrogen Skin Patch The skin patch is used in hormone replacement therapy, to deliver the hormone estrogen to women to relieve some of the symptoms of menopause. Estrogen can also be taken in pill form, but some studies have indicated that estrogen pills can cause an increase in the body’s production of a substance called C-reactive protein. This protein seems to increase the risk of heart disease. Another study indicated that the increase in C-reactive protein was twice as high if the estrogen was taken in pill form as opposed to as a skin patch. A possible explanation for this difference is that the active components in an estrogen pill must be metabolized by the liver before they enter the blood stream. The skin patch delivers the estrogen in a useable form directly to the blood stream, so lower dosages are needed. The disadvantages of the skin patch are that the adhesive and the moist conditions under the patch may, over an extended period of use, cause skin irritations. In addition, some people may have allergic reactions to one of the components of the patch. Other preferable methods of replacing estrogen may be from natural foods that are rich in estrogen, such as soybean products in the form of soymilk or tofu.

3.20 ACTIVITY: MAKING POLYMERS

(Pages 244–246)

PART 1: MAKING GUAR GUM SLIME—A CROSSLINKED POLYMER

Observations (a) The slime stretches and then returns to its original shape. It is stretchable and flexible. (b) The slime breaks. (c) The slime breaks with a sharp surface at the break. (d) The slime takes on the shape of a long string. (e) The slime softens and starts to liquefy.

Analysis (f) (a) Crosslinking holds polymer strands together. Any deformation of the slime is restored by the crosslinks between

polymer strands. (b) Crosslinks are broken by sharp pulling of the polymer. (c) Sharp force on the slime breaks all the crosslinks along the line of force, leaving the slime broken with a sharp

surface.

Jim

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(d) As the slime passes gently through the hole of the funnel, some crosslinks are broken and reformed, leaving the polymer with a new shape.

(e) The presence of an acid hydrolyzes the crosslinks, causing the slime to turn into a liquid.

Synthesis

(g)

Thickener Source Molecular structure Reasons for similar properties

Cornstarch germ of corn kernels polysaccharides: amylose and amylopectin

Carrageenan varieties of red seaweed

long-chain carbohydrate polymer (polysaccharide) made up of repeating sugar units

Gelatin beef bones and skin, treated with bases

protein polymer made up of amino acids

These polymers react with water, usually when heated, to form hydrated crosslinked molecules throughout the solution, resulting in a thickening of the solution.

PART 2: MAKING GLYPTALA POLYESTER

Observations (h) Glyptal is a hard clear plastic. It gets marred in contact with organic solvents such as acetone because it is soluble in

acetone.

Analysis (i) Sample properties: hard, clear, strong solid; insoluble in water but soluble in acetone (paint thinner or nail polish

remover).

Synthesis (j) It hardens quickly to form a protective coating that is insoluble in water. It is miscible with organic solvents that may

be present in paints. (k) This polymer could also be used in varnishes and as a substitute for glass (e.g., plastic containers, drinking glasses). (l) The hydroxyl group on the middle carbon of glycerol provides opportunity to form ester bonds with orthophthalic

acid, forming strong crosslinks. A hard plastic is therefore formed, which does not soften when heated. The hydrocarbon portions of the plastic molecule provide nonpolar groups, making the plastic insoluble in water, but soluble in an organic solvent such as acetone.

3.21 CASE STUDY: CONTACT LENSES


(Page 248)

Understanding Concepts 1. When a polymer is deformed, its polymer chains are forced out of alignment. Crosslinking pulls the polymer chains

back together, returning the lens to its original shape.

Jim

Rectangle


Making Connections

2. [Sample answer] This statement is valid. Properties of polymers can be changed by altering the type of functional groups and substituted groups on the monomers, and by altering the type of interchain linkages. There are numerous organic compounds that can act as monomers because carbon atoms can form four bonds and long carbon chains.

3. (a) Hard lenses: Plastic lenses (PMMA) replaced glass lenses for comfort, but did not allow sufficient oxygen to reach the eye. Soft lenses: PolyHEMA replaced hard contact lenses. Soft lenses are more comfortable and have improved oxygen permeability, but they are not long-lasting because they are easily deformed. Rigid gas-permeable lenses are made of a new polymer that is gas permeable and retains its shape; however, there is an increased risk of protein and lipid deposits on the lens.

(b) New polymers were developed for rigid gas-permeable lenses, and research is ongoing to develop new organic compounds with desired properties for use in improving vision and eye care.

4. [Sample answers] Desirable features include lenses that are gas permeable, rigid, and easy to maintain, that can be worn for long periods of time. Future developments depend on the design and testing of polymers with different functional groups and substituted groups, and varying degrees of crosslinking.

5. (a) [Sample answers] Some crosslinking gives the lens elasticity and comfort for the wearer; however, elasticity is at the expense of the lens retaining its shape for correcting vision. High water content in the lens is needed to provide oxygen to the eye; however, increased water content decreases the refractive index of the lens and lowers the corrective effect.

(b) [Sample answer] Some polymer molecules such as transparent plastics; some degree of crosslinking to provide rigidity as well as flexibility, and to keep shape with body temperature; selected functional groups that allow interaction with water but do not dissolve.

Extension 6. [Sample answer]

Drug delivery systems, e.g., nicotine patches, estrogen patches. Problem to be solved: Patients quitting smoking need a bridging program to relieve withdrawal from nicotine; patients requiring estrogen to relieve symptoms of menopause. Existing solution: nicotine gum, estrogen capsules. Problems: patients may forget to take medication. As well, a low but continuous dosage is most effective. Improved solution: Polymers may be used to provide an adhesive patch on the skin, allowing the nicotine or estrogen to be absorbed through the skin on a continuous basis.

Jim

Rectangle

NEL Unit 3 Summary Student Book Solutions 159

UNIT 3 SUMMARY

MAKE A SUMMARY

(Page 251)

(a) Front:



Alkanes CnHn+2

butane lighter fluid

Alkenes CnHn

propene propylene

Alkynes CnHn–2

ethyne acetylene

Back:



Alkanes smaller molecules are gases at room temperature, larger molecules tend to be liquids or soft solids; soluble in nonpolar solvents; generally unreactive

no functional groups; all C−C bonds are saturated


Alkenes smaller molecules are gases at room temperature, larger molecules tend to be liquids or soft solids; soluble in nonpolar solvents; undergo addition reactions

C=C van der Waals forces

Alkynes smaller molecules are gases at room temperature, larger molecules tend to be liquids or soft solids; soluble in nonpolar solvents; undergo addition reactions

C�C van der Waals forces


Front:



Alcohols

R−OH

2-butanol none

Ethers

R−O−R

ethoxypropane none

Back:



Alcohols soluble in water and some nonpolar solvents; react with carboxylic acids to form esters

hydroxyl group hydrogen bonds

Ethers soluble in nonpolar solvents oxygen atom bonded to two alkyl groups


Front:



Aldehydes R−CHO ethanal acetaldehyde

Ketones

R–C(O)−R

propanone acetone

Back:



Aldehydes boiling points intermediate between hydrocarbons and alcohols of similar size; soluble in polar and nonpolar solvents

carbonyl group at end of carbon chain


Ketones boiling points intermediate between hydrocarbons and alcohols of similar size; soluble in polar and nonpolar solvents

carbonyl group in interior of carbon chain


NEL Unit 3 Summary Student Book Solutions 161

Front:



Carboxylic acids

R−COOH

ethanoic acid acetic acid (vinegar)

Back:



Carboxylic acids soluble in water, turn litmus pink, react with alcohols to form esters

carboxyl group

−COOH

hydrogen bonds, van der Waals forces

Front:



Esters

RCOOR

methyl propanoate (none)

Back:



Esters less soluble in water than their parent acids; lower melting and boiling points than parent acids; not acidic; often have distinctive odours, e.g., fruity, peppermint

R–COO–R van der Waals forces

Front:



Amines

1-aminopropane (none)

Amides

ethanamide (none)


Back: Family Characteristic properties Characteristic

functional groups Intermolecular forces

Amines often have unpleasant odours; react with carboxylic acids to form amides; have higher boiling points and melting points than similar-sized hydrocarbons, lower boiling points and melting points than similar-sized alcohols; smaller amines are readily soluble in water

hydrogen bonds due to any –NH groups; van der Waals forces due to polar C–N bonds

Amides generally insoluble in water

hydrogen bonds due to any –NH groups

UNIT 3 PERFORMANCE TASK: MAKING SOAP

(Pages 253–255)

Analysis (a) The functional groups of glycerol are all hydroxyl groups, –OH. Glycerol is therefore an alcohol. It forms hydrogen

bonds in addition to van der Waals forces. (b) The functional group of stearic acid is the carboxyl group, –COOH, made up of a carbonyl group and a hydroxyl

group. Stearic acid is a carboxylic acid. It forms hydrogen bonds in addition to van der Waals forces due to the polar carbonyl groups. Stearic acid has low solubility in water because its long hydrocarbon chain “nullifies” the polarity of the carboxyl group, rendering it a more nonpolar molecule that has low solubility in a polar solvent.

(c) Water is formed. Therefore, this reaction is a condensation reaction.

(d)

ethanoic acid (acetic acid) CH3COOH(aq) + NaOH(aq) → CH3COONa(aq) + H2O(l)

Evaluation (e) [Sample answer] The soap did not harden; it remained greasy. We perhaps need to use more NaOH(aq). The soap did

not lather very well. It is possible that using distilled water in the procedure would solve this problem.

Synthesis (f) We would predict that glycerol has a higher boiling point than 1-propanol because glycerol has three hydroxyl

groups and 1-propanol has one. Glycerol would therefore form more hydrogen bonds than would 1-propanol, and thus more energy is required to separate the glycerol molecules to form a gaseous state.

(g) Glycerol is probably soluble in polar solvents because of the polar hydroxyl groups. It may be slightly soluble in nonpolar solvents because of the three-carbon backbone.

(h) Carbon dioxide and water would form as a result of the combustion of glycerol:

NEL Unit 3 Review Student Book Solutions 163

(i) Use organic solvents in a well-ventilated location or fume hood, away from ignition sources such as electrical sparks, open flames, and hot surfaces. Do not store solvents in direct sunlight or near heat sources, or in basements. Return unused portions immediately to the appropriate storage containers. Dispose of small amounts of ethanol (according to environmental restrictions) in the sink, followed by plenty of water.

(j) Detergents are made from long hydrocarbon chains and sulfuric acid. They are similar to soap molecules, which also have long carbon chains and a salt group at one end. Advantages of detergents are that they do not produce an insoluble “scum” with the calcium and magnesium ions in hard water, and they are generally less expensive than soap. Disadvantages of detergents are that they are generally not biodegradable and may damage the environment. They are made from non-renewable petroleum products.

UNIT 3 REVIEW

(Pages 256–259)


1. (a) HC≡CH (b) CH3CH(OH)CH3

(c)

(d) CH3COOH 2. (a) Fractional distillation separates the mixture of hydrocarbons in petroleum, collecting the fractions used in

gasoline. Cracking converts larger straight-chain hydrocarbons into the shorter branched-chain hydrocarbons that are valuable in gasoline.

(b) Three other useful fuels are jet fuel, kerosene, and diesel oil. 3. C, B, D, A. The reason for this order is that more polar compounds have higher boiling points as a result of increased

intermolecular forces. C is an alkane and is nonpolar. B is more polar than C because of its carbonyl group. D is more polar than B because of its –OH group, which is capable of hydrogen bonding. A is more polar than D because it has an –OH group and a carbonyl group.

4. (a) acetone (propanone)

(b) acetic acid (ethanoic acid)

(c) formaldehyde (methanal) HCHO (d) glycerol (1,2,3-propantriol)

(e) diethyl ether (ethoxyethane) CH3CH2—O—CH2CH3

5. (a) ethanol, 1-pentanol: Both molecules have a polar hydroxyl group, but the longer hydrocarbon chain in the pentanol increases its intermolecular van der Waals attractions.

(b) ethoxyethane, propanone: The carbonyl group in the ketone makes it more polar. Therefore, it has stronger intermolecular attractions.

(c) ethanal, ethanoic acid: The acid has an additional hydroxyl group that the aldehyde does not have, making it more polar and capable of hydrogen bonding; thus, the acid has stronger intermolecular attractions.

6. (a) propane, 1-propanol: Propane does not contain any polar groups and is therefore insoluble in water. Propanol contains a hydroxyl group, which allows hydrogen bonding and solubility in water.


(b) Methyl ethanoate, ethanoic acid: The ester is less soluble in water than is the carboxylic acid because the acid has a carbonyl group and a hydroxyl group capable of hydrogen bonding with water, but in the ester, the hydroxyl group is lost in the ester linkage; thus, the acid is more soluble in water.

(c) 2-butanone, 2-butanol: The ketone has a carbonyl group, but the alcohol has a hydroxyl group that can hydrogen bond with water. Therefore, 2-butanol is more soluble in water.

7. (a) 2-butanol:

(b) ethoxyethane: CH3CH2OCH2CH3

(c) 2-butanone: (d) ethanoic acid:

(e) methyl methanoate: 8. The solid formed is the ester. The ester has a lower melting point and solubility in aqueous solvents because it lacks

the hydroxyl group present in both alcohols and carboxylic acids, and thus does not hydrogen bond. 9. (a) triple bond in carbon chain: alkyne

(b) –OH (hydroxyl) group: alcohol (c) –COOH (carboxyl) group: carboxylic acid (d) terminal C=O (carbonyl) group: aldehyde (e) oxygen bonded to two carbon atoms: ether (f) –NH2 group: amine (g) C=O (carbonyl) group bonded to two carbon atoms: ketone (h) COO group: ester (i) C=O (carbonyl) group bonded to N atom: amide (j) C=O (carbonyl) group bonded to two carbon atoms: ketone (k) –COOH (carboxyl) group: carboxylic acid (l) double bond in carbon chain: alkene (m) oxygen bonded to two carbon atoms: ether (n) –OH (hydroxyl) group: alcohol (o) triple bond in carbon chain: alkyne (p) COO group: ester (q) terminal C=O (carbonyl) group: aldehyde (r) C=O (carbonyl) group bonded to two carbon atoms: ketone (s) –NH2 group: amine (t) –OH (hydroxyl) groups: alcohol (u) C=O (carbonyl) group bonded to N atom: amide (v) double bonds in carbon chain: alkene

10. (a)


(b) (c) (d)

(e)

11. (a) (b) (c)


(d)

12. (a) CH3CH2OH + 3 O2 → 2 CO2 + 3 H2O H2SO4

(b) CH2=CHCH2CH3 + H2O → CH3CH(OH)CH2CH3 (c) CH3COOH + HN(CH2CH2CH3)2 → CH3CON(CH2CH2CH3)2 + H2O

13. (a) Intermolecular bonding restores the polymer strands to their original position, after any stretching or other deformation, which makes the polymer elastic.

(b) For intermolecular bonding to occur, a monomer must be able to form bonds other than the bonds forming the polymer chain itself; that is, it must have an additional functional group (e.g., double bond, hydroxyl group, carboxyl group), other than the two involved in the polymer linkages, to link with another polymer chain.


14. The three alcohols have different boiling points that increase in the following order: methanol, ethanol, and 1-pentanol. The alcohols can be separated by fractional distillation, using common laboratory equipment. Each alcohol is collected at its boiling point and condensed. All three alcohols have hydroxyl groups capable of hydrogen bonding. The larger alcohols have longer nonpolar hydrocarbon chains that increase the van der Waals attractions between them.

15. Carefully read and follow the recommendations on the MSDS for every chemical substance that you use. Be aware of the flammability and combustibility of solvents. Use organic solvents in a well-ventilated location or in a fume hood, away from ignition sources such as electrical sparks, open flames, and hot surfaces. Do not store organic solvents in direct sunlight or near heat sources. Do not use or store organic solvents in basements. Return unused solvents immediately to the appropriate storage containers. Organic solvents may be toxic; never eat or drink in the vicinity of organic solvents and always wash your hands after use. Dispose of waste solvents according to environmental restrictions. Never pour them down the sink.

16. Looking at states of matter: the alcohol is more likely to be a liquid. The short chain carboxylic acid may be a liquid or a solid, and the long chain carboxylic acid is more likely a solid. The reason for this conclusion is that alcohols have hydroxyl groups that allow hydrogen bonding. The carboxyl groups have a carbonyl group in addition to a hydroxyl group, and thus have stronger intermolecular forces, and are more likely to be solids. The long-chain carboxylic acid also has stronger van der Waals forces and is thus most likely to be a solid.

When testing solubility in polar and nonpolar solvents, the alcohol and the short-chain carboxylic acid will likely be soluble in a polar solvent such as water because of the presence of hydroxyl groups. The long-chain carboxylic acid may be more soluble in nonpolar solvents because of the long hydrocarbon chain.

Using the litmus test, the alcohol would not change blue litmus to pink, but the two acids would. 17. (a) ethanol, CH3CH2OH

(b) ethanoic acid (acetic acid), CH3COOH (c) CH3COOH + CH3CH2OH → CH3COOCH2CH3 + H2O (d) Esterification reaction (or condensation reaction) (e) Eye protection, lab apron, test tubes, pipettes, hot water bath (large beaker of hot water), evaporating dish,

sulfuric acid (f) Working in a fume hood, place a small volume of the ethanoic acid in a test tube, with a few drops of

concentrated sulfuric acid as a catalyst. Add a small volume of ethanol to the contents of the test tube. Heat the test tube and contents in the hot water bath for a few minutes. Pour the contents of the test tube into some cold water in an evaporating dish.

(g) Wear eye protection and a lab apron. Wear gloves when handling concentrated sulfuric acid. Work in a fume hood or a well-ventilated area. Keep the ethanol away from open flames, electric sparks, and hot surfaces. Immediately return unused materials to the proper storage containers. Waft when smelling the ester produced. Dispose of waste solvents in proper containers.


18. (Model-building exercise) 19. (a) The borax forms crosslinks between the molecules of glue, changing the glue from a thick liquid to a soft solid.

(b) Make several batches of slime using the same ingredients, but make each batch with a different quantity of borax. Decreasing or increasing the amount of borax added would probably decrease or increase the elasticity of the slime because the number of crosslinks formed would change.

Making Connections

20. (a) methyl chloride: CH3Cl chlorofluorocarbon (CFCs, Freon) e.g., CF2Cl2 hydrochlorofluorocarbons (HCFCs) e.g., CHFCl2 hydrofluorocarbons (HFCs) e.g., CH2F2 (b) These molecules all contain carbon and some combination of hydrogen, chlorine, or fluorine. They were all

considered unreactive and safe to use and to discharge into the environment. (c) Methyl chloride is toxic. Leakage of the coolant resulted in several deaths. Freon appears to damage the upper

ozone layer, causing ozone “holes” that leave us unprotected from harmful UV radiation. HCFCs and HFCs cause less damage to the ozone layer, but HFCs release carbon dioxide, a major greenhouse gas.

(d) In the presence of UV light, Freon decomposes, releasing highly reactive chlorine atoms. The chlorine destroys the ozone molecules in the stratosphere. HCFCs and HFCs readily decompose in the atmosphere and have less time to cause damage to the ozone layer. HCFCs still contain chlorine, but HFCs contain no chlorine and are the preferred substitute for CFCs.

21. (a) glucose

glycerol

ethylene glycol

rubbing alcohol (2-propanol)

(b) In order of increasing melting points and boiling points: rubbing alcohol, ethylene glycol, glycerol, glucose. The reason for this order is the increasing number of hydroxyl groups (1, 2, 3, 6, respectively), which increase the number of hydrogen bonds formed, thus increasing the amount of energy required to separate the molecules to melt or to boil.

(c) All four substances should be soluble in water because of the number of polar hydroxyl groups that can hydrogen bond with water. All four substances are probably not soluble in a nonpolar solvent, such as gasoline, because they do not contain long nonpolar hydrocarbon chains.

(d) Ethylene glycol is highly toxic and has a sweet taste. Animals or young children may taste ethylene glycol spills and drink it because of its sweetness.

(e) These four compounds seem to have increasing sweet taste as the number of hydroxyl groups per molecule increases. This trend may support the hypothesis that taste receptors respond to functional groupsin this case, the hydroxyl groups.

22. (a) CH3COOH + CH3CH2CH2CH2CH2OH → CH3COOCH2CH2CH2CH2CH3 (b) Student answers will vary, but should refer to the raw materials and the method of synthesis. (c) The most commonly used natural source of vanilla flavouring is the vanillin plant, Vanilla planifolia, a member

of the orchid family. Vanillin, a glucoside, is extracted from ripe vanillin beans, using ethanol and water, under cool temperatures to reduce flavour loss. The extract is then aged from a few days to several years.


Synthetic vanilla flavouring contains a blend of natural vanilla and synthetic chemicals, and cannot be legally labelled “natural.” The first synthetic vanilla was made from coniferin, and later from euganol, found in cloves. More recently, synthetic vanilla is made from ethyl vanillin (made from coal tar), or lignin vanillin, a byproduct of the paper industry. In the 1930s, the Ontario Paper Company solved an environmental problem by turning their industrial waste, a sulfite liquor, into synthetic vanilla.

23.

Advantages: is relatively easy to make; has not been shown to cause cancer; is 200 times sweeter than sugar. Disadvantages: has a shelf life of about six months, after which it loses its sweetness; breaks down at high temperatures, so it cannot be used in baking

Advantages: is easy to make; is stable when heated; is approximately 300 times sweeter than sugar Disadvantages: may cause cancer in rats (Some studies show that saccharin increases bladder cancer, while other studies show that there is no correlation between the amount of saccharin and the rate of cancer in rats.)

Advantages: is stable at high temperatures; has a very long shelf life (about 3–4 years); has not been shown to cause cancer Disadvantages: none known

24. Desired properties of polymers for use in the dental industry include high tensile strength, durability, insolubility in water, non-toxicity, resistance to softening at high temperatures (e.g., hot drinks). • Dental polymers have three main components: a polymer matrix; fillers of various types, sizes, shapes; and a

phase that bonds the other two phases. Shrinkage of the polymer is a common shortfall. • Monomers may form branched or linear polymer chains. The linear polymer chains can have a parallel alignment

and form crosslinks between chains, which allows for a crystalline structure that produces more of the desired properties. Dental monomers form strong hydrogen bonds, influencing the polymerization process and the network structure formed.

• The polymerization process is usually initiated by chemical reduction–oxidation reactions, or by photochemical redox reactions. Dental fillings are generally cured using a curing lamp, a process that results in 2–3% shrinkage,


which leads to eventual detachment of the filling from the cavity. Pulse lasers can cause numerous initiations of the polymerization at the onset of curing, and may reduce the shrinkage of the fillings.

25. [Sample answers] paper (natural, polymer); plastic pen (synthetic, polymer); cotton and polyester shirt (natural and synthetic, polymer); running shoes (synthetic, polymer); ketchup (natural, polymer); vinegar (natural, not polymer); butter (natural, not polymer); gasoline (natural, not polymer); television set (synthetic, not polymer); CDs (synthetic, polymer)

26. Students might give any three of the following:

Synthetic polymer Use Monomer Type of reaction

polyethene sheet plastic, garbage bags

ethane addition reaction

polypropene rope propene addition reaction

polystyrene foam cups styrene addition reaction

nylon fabrics dicarboxylic acids and diamines

condensation reaction

Dacron fabrics dicarboxylic acids and diamines

condensation reaction

27. Student answer will vary. Here are some sample points in a report on gasohol. Ethanol and gasoline blends provide environmental benefits: • Ethanol is clean burning, with lower carbon monoxide emissions than regular gasoline. • Ethanol is low in reactivity and high in oxygen content, making it an effective tool in reducing ozone pollution. • Ethanol provides a safe replacement for toxic octane enhancers in gasoline such as benzene, toluene, and xylene. • Ethanol has a nonpolar carbon chain, making it a good solvent for the nonpolar hydrocarbons in gasoline;

however, the polar hydroxyl group renders it soluble in water, so dissolved water droplets may form ice at low temperatures, blocking gasoline flow.

Extension

28. The solubility of organic halides in water is related to the length of the nonpolar hydrocarbon portion of the alkyl group. If the alkyl group is small, the halide may be water-soluble and thus can be excreted by an organism as waste. If the alkyl group is large, the molecule may be insoluble in polar solvents such as water, and soluble in nonpolar solvents such as the fat tissue in the organism. In this case, the organic halide is not excreted and is stored in the body. When organisms higher in the food chain eat a number of the affected organisms, the stored organic halides accumulate to high concentrations in the consumer, reaching toxic levels.

29. (a)

(b) PABA is benzoic acid with an added NH2 group, in position 4; thus, it has an additional polar group that is capable of hydrogen bonding. Prediction: PABA is a solid at room temperature, with a boiling point higher than that of benzoic acid. The presence of the carboxyl group and the amino group makes the molecule highly polar and capable of hydrogen bonding, so PABA might be soluble in water. The presence of the benzene ring probably makes it soluble in nonpolar solvents such as alcohol and ether. With the presence of both a carboxyl group and an amino group, PABA can undergo condensation reactions with other molecules, or undergo condensation polymerization with other PABA molecules.

(c) [Sample answer] Sunscreens provide physical barriers to UV light (zinc oxide and titanium dioxide compounds), or chemical barriers. PABA is a chemical sunscreen that absorbs radiation in wavelengths that are invisible to the human eye. PABA is not soluble in water and therefore must be dissolved in alcohol for use; however, most of the PABA derivatives are water soluble. Sunlight consists of UVA rays (that penetrate deep into the base layer of skin) and UVB rays (burning rays). Both types of UV rays contribute to skin burning and skin cancer. PABA provides mostly UVB coverage between 260 and 330 nm. Consumers should select a sunscreen that screens out both UVA and UVB rays—the “broad spectrum” sunscreens.


There are some hazards to using PABA. Although sunscreens should be used every day to prevent premature aging and skin cancer (80% of the Sun’s ultraviolet rays pass through the clouds on a cloudy day), sun exposure is needed for vitamin D. Thus, regular users of sunscreen may require vitamin D supplements. The original PABA was sometimes unpopular because it stained clothing. PABA esters, such as glycerol PABA, pentyl dimethyl PABA, and octyl dimethyl PABA, are now used. Some people are sensitive to PABA and its esters and should use other sunscreens.

30. The surfactant in bubble bath is usually sodium lauryl sulfate (or, in more expensive or milder brands, sodium laureth sulfate or sodium lauryl sulfoacetate). Castile soap (made from olive oil) can also be used. To help the surfactant to form bubbles, glycerine (or sometimes coconut or olive oil) is added. The surfactant (“surface active agent”) reduces the surface tension of water by interacting with the water molecules. With less surface tension, bubbles of air in the water remain trapped just below the surface. The addition of glycerine or oil helps the foam to last longer by slowing down the rate at which the bubbles’ water “skin” evaporates.

31. (a) Starch is the main method of energy storage for plants, as seeds or in tubers. Starches are polymers of glucose, joined in branched or unbranched chains. These chains have a helical structure, and are sufficiently small to be soluble in water, which makes the molecules mobile and transportable to different parts of the plant, an important property for an energy source.

(b) Glycogen is a starch-like molecule produced by animals. It is stored in the muscles as a ready source of energy, and also in the liver, where it helps to regulate the blood glucose level. Like starch, glycogen has a helical structure, which makes it soluble in water and readily transportable to different parts of the animal for energy.

(c) Cellulose is made in plants and provides structure and support. In cellulose, the glucose monomers are joined to form linear chains that align side by side, favouring hydrogen bonding between neighbouring polymer chains. These interlinked chains produce a rigid structure of layered sheets, giving cellulose its exceptional strength, and making it insoluble in water.

04 unit 1 sb - quia is also a component of natural gas. propane is a fuel used in gas barbecues....

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