Fossil Fuels and Carbon Compounds

Transcription

1 Topic 7 Fossil Fuels and arbon ompounds Unit 25 Fossil fuels Unit 26 omologous series, structural formulae and naming of carbon compounds Unit 27 Alkanes and alkenes Unit 28 Addition polymers

2 Key o ncepts omologous series, structural formulae and naming of carbon compounds Unique nature of carbon Structural formula, condensed structural formula and skeletal formula omologous series and systematic naming of alkanes, alkenes, alkanols and alkanoic acids Fossil Fuels and arbon ompounds Fossil fuels Origins and uses Fractional distillation of petroleum and properties of fractions onsequences of using fossil fuels

3 Alkanes and alkenes Risks and benefits of using fossil fuels racking of fractions of petroleum Important reactions of alkanes and alkenes Addition polymers Monomers, polymers and repeating units Structures, properties and uses Economic importance of plastics Environmental issues associated with the use of plastics

4 Topic 7 Fossil Fuels and arbon ompounds Unit 25 Fossil fuels 25.1 Fossil fuels a major energy source 25.2 Importance of petroleum 25.3 What is petroleum composed of? 25.4 Fractional distillation of petroleum 25.5 Uses of fractions of petroleum 25.6 Demand for various fractions of petroleum 25.7 ombustion of hydrocarbons 25.8 arbon dioxide and the greenhouse effect 25.9 Major air pollutants from cars, factories, incinerators and power stations Measures for reducing emission of air pollutants Impact of using fossil fuels on our quality of life and the environment

5 Unit 25 Fossil fuels Summary 1 The major fossil fuels are coal, petroleum and natural gas. 2 Fossil fuels were formed from the remains of plants and animals that lived millions of years ago. 3 Petroleum is a mixture mainly composed of hydrocarbons. ydrocarbons are compounds that contain only atoms of carbon and hydrogen. hydrocarbons found in petroleum alkanes cycloalkanes aromatic hydrocarbons 4 Fractional distillation separates petroleum into fractions with different boiling point ranges. Fraction Boiling point range ( ) Number of carbon atoms per molecule General Properties Refinery gases below Petrol, naphtha Kerosene Diesel oil Fuel oil, lubricating oil and wax over 350 above 25 fractions containing hydrocarbons with a smaller number of carbon atoms in their molecules: lighter in colour less viscous easier to evaporate more flammable burn with a clearer flame fractions containing hydrocarbons with a greater number of carbon atoms in their molecules: darker in colour more viscous more difficult to evaporate less flammable burn with a sootier flame 5 The main uses of refined petroleum are: a) as fuels for transportation; b) as fuels for generating electricity; c) as fuels for heating; and d) as raw materials in the petrochemical industry. Exam tips Do NOT use the terms petroleum and petrol interchangeably. Fractional distillation involves a physical change. Ethene is NOT manufactured directly by fractional distillation of petroleum.

6 Topic 7 Fossil Fuels and arbon ompounds Example Petroleum can be separated into different products such as petrol, diesel oil and fuel oil by a certain process. a) Name the process. (1 mark) b) Explain whether petrol or diesel oil has a higher viscosity. (2 marks) c) Explain whether petrol or diesel oil is a cleaner fuel. (2 marks) Answer a) Fractional distillation (1) b) Diesel oil has a higher viscosity. (1) The van der Waals forces between the molecules in diesel oil are stronger than those in petrol. (1) c) Petrol is a cleaner fuel. (1) Petrol burns more completely / has a lower carbon content than diesel oil. (1) Remarks* Viscosity has been discussed in Topic 6 Microscopic World II. The viscosity of a liquid is a measure of a liquid s resistance to flow. The viscosity of a liquid depends on: the strength of attractive forces between molecules; and the tendency of molecules to become entangled with each other. A liquid with strong intermolecular forces has a higher viscosity than one with weak intermolecular forces. If the molecules of a liquid are in the form of long chains, they can become entangled and the viscosity of the liquid will be high. Questions often give two fuels and ask which is a cleaner fuel. e.g. omparing liquefied petroleum gas (LPG) and diesel oil Summary 1 ombustion of hydrocarbons is an exothermic reaction. 2 Burning of fossil fuels produces carbon dioxide and water vapour, which contribute to the greenhouse effect. 3 Major air pollutants from using fossil fuels include: a) carbon monoxide; b) unburnt hydrocarbons / volatile organic compounds;

7 Unit 25 Fossil fuels c) suspended particulates; d) oxides of nitrogen; e) sulphur dioxide. 4 The table below summarizes possible measures for reducing the emission of air pollutants from the combustion of fossil fuels. Pollutant Oxides of nitrogen Sulphur dioxide Particulates Measures for reducing the emission of the pollutant installing catalytic converters in exhaust systems of motor vehicles installing low nitrogen oxide burners in power stations using low-sulphur coal instead of high-sulphur coal installing flue gas desulphurization systems or scrubbers in power stations using electrostatic precipitators in power stations installing particulate removal devices in motor vehicles Exam tips Although carbon dioxide is a greenhouse gas, it is NOT considered as an air pollutant. Water vapour is a greenhouse gas. arbon dioxide does NOT cause acid rain. Questions often ask about the current air pollution problems in ong Kong and possible measures for reducing the emission of air pollutants. e.g. using natural gas to replace coal in generating electricity; using electricity to replace petrol to drive cars. Questions often ask about acid rain. acid rain refers to rain with p less than 5.6; air pollutants that lead to acid rain (NO x and SO 2 ); what environmental problems are caused by acid rain. Students should be able to match the device with the air pollutant(s) it can reduce. Gasohol is a mixture of ethanol and petrol. Advantages of using gasohol over ethanol: gasohol is less flammable; more energy can be obtained from gasohol. Advantages of using gasohol over petrol: gasohol undergoes complete combustion more readily; gasohol gives less carbon monoxide / particulates / soot / smoke upon combustion.

8 Topic 7 Fossil Fuels and arbon ompounds Example The exhaust gas of motor vehicles contains carbon monoxide, oxides of nitrogen and particulates. a) i) Explain why the exhaust gas contains oxides of nitrogen. (1 mark) ii) State ONE environmental problem associated with the emission of oxides of nitrogen into the atmosphere. (1 mark) b) State ONE health hazard associated with particulates. (1 mark) c) Suggest a device that can be installed in a motor vehicle to reduce the emission of carbon monoxide and oxides of nitrogen. Describe the reactions involved and write relevant chemical equations. (3 marks) Answer a) i) Inside the engines of motor vehicles, the air gets so hot that nitrogen and oxygen react together, forming oxides of nitrogen. (1) ii) Formation of acid rain / formation of photochemical smog with unburnt hydrocarbons. (1) b) Irritate respiratory system (1) c) atalytic converter (1) Oxides of nitrogen react with carbon monoxide as they pass through the catalyst. Nitrogen and carbon dioxide are formed. (1) 2O(g) + 2NO(g) catalyst N 2 (g) + 2O 2 (g) The excess carbon monoxide is oxidized by air to carbon dioxide. catalyst 2O(g) + O 2 (g) 2O 2 (g) (1) Remarks* Questions often ask how carbon monoxide and oxides of nitrogen are formed inside motor vehicle engines. Among all the devices for reducing air pollution, questions ask about reactions occurring in a catalytic converter most often. Be careful with the spelling of the term catalytic converter. The following measures can help reduce the level of carbon monoxide at the road side: using liquefied petroleum gas a fuel for motor vehicles; installing catalytic converter in motor vehicles. atalytic converters increase the emission of carbon dioxide. Thus, installing them do NOT help reduce global warming. A catalytic converter is NOT used to remove sulphur dioxide.

9 Unit 26 omologous series, structural formulae and naming of carbon compounds Unit 26 omologous series, structural formulae and naming of carbon compounds 26.1 A look at molecules of compounds in petroleum 26.2 hemistry of carbon compounds 26.3 Representing molecular structures of carbon compounds 26.4 Molecular models 26.5 Functional groups 26.6 omologous series 26.7 The alkanes 26.8 Naming straight-chain and branched-chain alkanes 26.9 Naming alkenes Naming alkanols Naming alkanoic acids Physical properties of alkanes

10 10 Topic 7 Fossil Fuels and arbon ompounds Summary 1 arbon compounds can be represented by structural formulae, condensed structural formulae and skeletal formulae. Structural formula ondensed structural formula Skeletal formula 3( 2) A functional group is an atom, or a group of atoms, which determines most of the properties of a compound. 3 A family of compounds containing the same functional group is called a homologous series. Members in a homologous series show the following characteristics: a) have the same general formula; b) each member differs from the next by a 2 unit; c) show a gradual change in physical properties; and d) show similar chemical properties. 4 Alkanes have the general formula n 2n+2. Name Molecular formula ondensed structural formula Methane 4 4 Ethane Propane Butane Pentane exane eptane Octane The IUPA name for a branched-chain alkane consists of two parts: Prefixes Parent identify the alkyl groups and give their locations describes the main carbon chain

11 Unit 26 omologous series, structural formulae and naming of carbon compounds 11 5 Some common homologous series and functional groups omologous series General formula Functional group Naming Example(s) Alkenes n 2n Alkanols n 2n+1O O name the compounds with the rules as if for alkanes, but using the suffix ene instead of ane name the compound by replacing the last letter e of the corresponding alkane by the suffix ol 3 2= 2 but-1-ene 3= 3 but-2-ene O butan-1-ol 3 2(O) 3 butan-2-ol Alkanoic acids n 2n+1OO O O name the compound by replacing the last letter e of the corresponding alkane by the suffix oic acid; the carbon atom of the carboxyl group is assigned number OO butanoic acid 6 a) The melting points and boiling points of alkanes rise as the number of carbon atoms in the alkane molecules increases. Name Molecular formula Melting point ( ) Boiling point ( ) State at room temperature and pressure Methane Ethane Propane Butane gas Pentane exane liquid Boiling point of alkane ( ) b) Alkanes are insoluble in water. Number of carbon atoms in the alkane molecule

12 12 Topic 7 Fossil Fuels and arbon ompounds Exam tips Students should be able to distinguish between the structural formula and the molecular formula of a compound. Students should be able to recognize the number of carbon atoms in the parent chain of a compound. The carbon atoms may NOT be in a straight line. e.g. Br The IUPA name of the above compound is 3-bromobut-1-ene O 4 3 The IUPA name of the above compound is butan-2-ol. 3, O The IUPA name of the above compound is 2-methylbutan-2-ol. When drawing the structures of different compounds with the same molecular formula, do NOT represent the same compound in different ways. e.g. 3 and are two different ways of representing hexane. 3 3 and are two different ways of representing 2-methylpentane.

13 Unit 26 omologous series, structural formulae and naming of carbon compounds 13 Example Both pentane ( 5 12 ) and octane ( 8 18 ) are members of the same homologous series. a) Name the homologous series to which pentane and octane belong. (1 mark) b) Using pentane and octane as examples, illustrate TWO characteristics of members of a homologous series. (2 marks) Answer a) Alkanes (1) b) Any two of the following: Members in a homologous series have the same general formula. The general formula for pentane and octane is n 2n+2. (1) Members in a homologous series show a gradual change in physical properties. The boiling point / melting point / viscosity of octane is higher than that of pentane. (1) Members in a homologous series show similar chemical properties. Both pentane and octane undergo substitution reaction with bromine / chlorine. (1) Remarks* Members in the same homologous series have the same general formula, NOT the same molecular formula. The relative molecular mass of each successive member differs by 14 (i.e. relative atomic mass of + 2 x relative atomic mass of ).

14 14 Topic 7 Fossil Fuels and arbon ompounds Unit 27 Alkanes and alkenes 27.1 Risks and benefits of using fossil fuels to the society and environment 27.2 Saturated and unsaturated hydrocarbons 27.3 Important reactions of alkanes 27.4 Meeting the demand for the petrol fraction from fractional distillation of petroleum 27.5 racking of fractions of petroleum 27.6 Importance of cracking 27.7 Alkenes 27.8 Physical properties of alkenes 27.9 Important reactions of alkenes Wind power An alternative source of energy

15 Unit 27 Alkanes and alkenes Summary 1 ydrocarbons can be classified as saturated and unsaturated. hydrocarbons saturated containing only bond(s) unsaturated containing = or bond(s) 2 The following table summarizes important reactions of alkanes. Reaction 1 ombustion in a good supply of oxygen, alkanes burn completely to form carbon dioxide and water omplete combustion: 5 12(g) + 8O 2(g) Examples 5O 2(g) + 6 2O(l) Incomplete combustion: 5 12(g) O 2(g) 5O(g) + 6 2O(l) 5 12(g) + 3O 2(g) 5(s) + 6 2O(l) 2 Substitution reaction with halogens formation of haloalkanes 4(g) + l 2(g) 3l(g) + l 2(g) 2l 2(l) + l 2(g) l 3(l) + l 2(g) 3l(g) + l(g) 2l 2(l) + l(g) l 3(l) + l(g) l 4(l) + l(g) Exam tips Questions often ask students to decide which of the two given compounds will burn with a more sooty flame. e.g. Which compound, pentane ( 5 12 ) or octane ( 8 18 ), will burn with a more sooty flame? Explain. Octane will burn with a more sooty flame. Octane has a higher percentage of carbon by mass. Its possibility of undergoing incomplete combustion to give carbon is higher.

16 16 Topic 7 Fossil Fuels and arbon ompounds Example A non-luminous flame is obtained when the air hole of a Bunsen burner is fully open. Methane is one of the components of the gaseous fuel used in the Bunsen burner. With reference to methane, explain why the flame obtained is non-luminous. (2 marks) Answer Enough oxygen is provided when the air hole is fully open. (1) Methane undergoes complete combustion to give carbon dioxide and water. (1) Remarks* When using a Bunsen burner with the air hole closed, the fuel undergoes incomplete combustion. A luminous flame is obtained. Example Under suitable conditions, 2 6 reacts with Br 2 to give 2 5 Br. a) State the conditions required for the reaction. (2 marks) b) State ONE observable change for the reaction. (1 mark) c) Outline the mechanistic steps involved. (4 marks) Answer a) Expose a mixture of ethane and bromine vapour under sunlight / ultraviolet light. (1) Use a mixture of 2 6 and Br 2 in a mole ratio of 1 : 1. (1) b) The brown colour of the bromine vapour fades. (1) c) Initiation Br Br 2 Br (1) Propagation + Br + Br (1)

17 Unit 27 Alkanes and alkenes 17 + Br Br Br + Br (1) Termination Any one of the following: Br + Br Br Br (1) + Br Br (1) + Remarks* This substitution reaction of alkane will NOT occur in the dark. This substitution reaction is a redox reaction Br Br + Br The oxidation number of Br decreases from 0 to 1. Students should be able to spell correctly names of the steps involved in a free radical substitution mechanism: initiation, propagation and termination. This reaction is NOT an effective way of preparing bromoethane because it gives a mixture of products (e.g. 3 Br 2, 3 Br 3, etc.) (1)

18 18 Topic 7 Fossil Fuels and arbon ompounds Summary 1 a) The melting and boiling points of alkenes are very close to those of the corresponding alkanes. Name ondensed structural formula Melting point ( ) Boiling point ( ) State at room temperature and pressure Ethene 2= Propene 3= gas But-1-ene 3 2= Pent-1-ene 3( 2) 2= ex-1-ene 3( 2) 3= liquid b) Alkenes are insoluble in water. 2 Alkenes are unsaturated hydrocarbons. They undergo addition reactions. + X Y X Y 3 The following table summarizes two addition reactions of alkenes. These reactions can be used as tests for unsaturated compounds. Reaction Examples With bromine dissolved in an organic solvent the orange solution of bromine becomes colourless rapidly when shaken with an alkene (g) + Br 2 (in organic solvent) (in organic solvent) Br Br With cold acidified dilute potassium permanganate solution the purple solution of potassium permanganate becomes colourless rapidly when shaken with an alkene (g) + [O] + 2O(l) (aq) O O 4 The following diagram summarizes some important information about cracking. racking The breaking down of larger hydrocarbon molecules with heat or catalyst to produce smaller hydrocarbon molecules. Importance of cracking Producing extra petrol to meet demands As a source of alkenes to make a great variety of chemicals

19 Unit 27 Alkanes and alkenes 19 Examples: (l) 7 16 (l) (g) (g) tetradecane heptane propene ethene (a component of petrol) (l) (l) (g) tetradecane dodecane ethene Exam tips racking is a chemical change. It is an endothermic reaction. It results in an increase of number of molecules. Questions may ask students to compare cracking and fractional distillation. Both involve heating. racking is a chemical change while fractional distillation is a physical change. Questions often ask about the laboratory set-up for cracking. Do NOT confuse this laboratory set-up with that for fractional distillation or reflux. unglazed porcelain pieces (as a catalyst) gaseous product mineral wool soaked with medicinal paraffin heat clamp water The reaction between an alkene and bromine / cold acidified dilute potassium permanganate solution is an addition reaction, NOT additional reaction. For the reaction between acidified dilute potassium permanganate solution and excess propene, the oxidation number of manganese changes from +7 to +2; the acidified potassium permanganate solution is decolorized; the structure of the organic product is 3 (O) 2 O. A = bond can only react with a stronger oxidizing agent, e.g. acidified potassium permanganate solution, but NOT with a weaker one such as acidified potassium dichromate solution.

20 20 Topic 7 Fossil Fuels and arbon ompounds Questions often ask about chemical tests for distinguishing between an alkane (a saturated hydrocarbon) and an alkene (an unsaturated hydrocarbon). Do NOT just state a chemical test; mention the colour change in each case, NOT just the final colour. Test Bromine (in organic solvent) Acidified dilute KMnO 4 (aq) Alkane the solution changes from orange to colourless slowly under light no observable change Observation Alkene the solution changes from orange to colourless rapidly in the dark the solution changes from purple to colourless Alkenes give negative results towards acidified dilute potassium dichromate solution. Therefore the reagent ANNOT be used to distinguish an alkene from an alkane. Example onsider the following set-up of an experiment. unglazed porcelain glass wool with kerosene heat tube A tube B tube blue litmus solution acidified KMnO 4 (aq) a) What is the chemical process that occurs in the experiment. (1 mark) b) What is the function of the unglazed porcelain? (1 mark) c) Will there be a colour change in each of the following solutions? Explain your answer. i) Solution in tube B (2 marks) ii) Solution in tube (2 marks) Answer a) racking (1) b) As a catalyst (1) c) i) There is no colour change in the solution (1) because no acidic gas is formed in the process. (1) ii) There is a colour change in the solution / the solution changes from purple to colourless (1) because alkenes are formed in the process. (1)

21 Unit 27 Alkanes and alkenes 21 Remarks* Questions often ask about the cracking process. racking occurs when kerosene passes over the unglazed porcelain. Vaporization of kerosene occurs when the glass wool is heated. No chemical reaction occurs at the glass wool. Example Dodecane ( ) can be cracked into ethene and a straight-chain alkane X such that the mole ratio of ethene : straight-chain alkane X is 2 : 1. a) Write a chemical equation for this reaction. (1 mark) b) A student performed an experiment to crack dodecane and collect the gaseous products by using a boiling tube. i) The student added a few drops of bromine dissolved in an organic solvent into the boiling tube containing the gaseous products. The orange colour of the bromine solution disappeared immediately. Why? (2 marks) ii) The student then dropped more bromine solution into the boiling tube until the orange colour of the bromine solution persisted. After about 10 minutes, the orange colour disappeared. Why? (2 marks) Answer a) (1) b) i) The products of cracking contained alkenes / unsaturated hydrocarbons (1) which decolorized the bromine solution rapidly by addition reaction. (1) ii) The products of cracking contained alkanes / saturated hydrocarbons (1) which decolorized the bromine solution slowly by substitution reaction. (1) Remarks* Questions often ask students to deduce molecular formulae of cracking products or write a chemical equation for the reaction. Notice that the number of carbon / hydrogen atoms on the left-hand side and the right-hand side of the equation are equal. e.g Number of atoms on left-hand side = 12 = 2 x = number of atoms on right-hand side Number of atoms on left-hand side = 26 = 2 x = number of atoms on right-hand side Questions often ask about the reaction between bromine and alkene.

22 22 Topic 7 Fossil Fuels and arbon ompounds Unit 28 Addition polymers 28.1 Plastic items in modern homes 28.2 Why are plastics so useful? 28.3 What is a polymer? 28.4 Polymerization of ethene 28.5 The rise of the modern plastics industry 28.6 Addition polymerization 28.7 Some common addition polymers 28.8 Uses of some common addition polymers 28.9 Relating structures of thermoplastics to their thermal properties Economic importance of plastics Environmental issues associated with the use of plastics ommon methods for treating plastic waste Other possible solutions to plastic waste disposal problems The use of plastics for packaging: any disadvantages?

23 Unit 28 Addition polymers Summary 1 Petroleum is the most important raw materials used in the production of plastics. 2 Plastics are polymers. A polymer is a compound which consists of very large molecules formed by joining together many small molecules repeatedly. 3 Polymerization is the process of repeatedly joining together many small molecules to form very large molecules. 4 A repeating unit is the smallest part of a polymer molecule, and the whole polymer structure can be obtained by repeating it. 5 Addition polymerization is a reaction in which monomer molecules join together repeatedly to form polymer molecules. No atoms are lost from the monomer molecules during the reaction. 6 Some common addition polymers are shown below: Polymer Structure of monomer Structure of polymer Low density polythene (LDPE) n igh density polythene (DPE) n Polypropene (PP) 3 3 n l l Polyvinyl chloride (PV) n Polystyrene (PS) n 3 3 Perspex O 3 O 3 O O n The above addition polymers are thermoplastics. They can be melted or softened by heat at relatively low temperatures.

24 24 Topic 7 Fossil Fuels and arbon ompounds 7 A comparison of methods for treating plastic waste. Method for treating plastic waste Landfilling Incineration Recycling Pyrolysis Advantages a lot of plastic waste can be treated in a short period of time d o e s n o t c a u s e m u c h a i r pollution volume of solid waste can be greatly reduced energy can be produced reduce landwastage the amount of plastic waste can be reduced conserve petroleum which is nonrenewable plastic waste can be converted into useful products conserve raw materials useful products (e.g. methane, ethene) can be obtained wasting land Disadvantage(s) degradation of plastic takes a long time m a y c a u s e p o l l u t i o n o f underground water slow release of toxins from landfill sites toxic gases are produced the cost of operating a controlled incineration plant is high it is difficult to separate plastic waste from other waste it is difficult to separate different plastic waste many plastics lose their original properties over successive recycling cycles it is difficult to remove additives in plastic waste the process is uneconomical a lot of energy is required Exam tips Questions often ask about the advantages of using plastics over other materials for making various objects. e.g. Suggest an advantage of using plastic over metal in making each of the following objects: Object made asing for an electric rice cooker Drainage pipe elmet for soldier Advantage of using plastic over metal plastic can prevent electricity leakage plastic does not corrode plastic has low density Be careful with the term addition polymerization, NOT additional polymerization. The = bonds in benzene and phenyl group of aromatic compounds do NOT undergo addition polymerization. e.g. 2 3 does NOT undergo addition polymerization.

25 Unit 28 Addition polymers 25 Do NOT confuse monomer with repeating unit. When asked to give the repeating unit of a polymer, do NOT add the value n. e.g. the repeating unit of polythene is, NOT. n When writing an equation for polymerization, remember to put the coefficient n in front of the monomer. e.g. n 3 propene 3 polypropene n Spell the term biodegradable correctly. The majority of household solid waste is treated by landfilling whereas the rest is done by recycling. Only thermoplastics are recycled by re-melting and re-shaping. Questions often ask students to compare the advantages and disadvantages of possible methods for treating plastic waste. Example Manufacturers sometimes use polyvinyl chloride (PV) to make products, such as water pipes and waterproof boots. water pipe waterproof boots a) i) Draw the structure of the monomer of PV. (1 mark) ii) What characteristic in the structure of the monomer enables it to act as a monomer? (1 mark)

26 26 Topic 7 Fossil Fuels and arbon ompounds b) Adding suitable plasticizers can reduce the rigidity of PV, rendering it suitable for making waterproof boots. plasticizer molecules polymer chains Explain how plasticizers can help reduce the rigidity of PV in terms of intermolecular attractions between polymer chains. (1 mark) c) Incineration is one of the ways to dispose of PV waste. owever, it may lead to pollution problems. i) Suggest TWO air pollutants that will be produced during the incineration of PV waste. (2 marks) ii) State ONE harmful effect of each pollutant suggested in (i). (2 marks) iii) Suggest ONE way to reduce the emission of each pollutant suggested in (i). (2 marks) Answer a) i) l (1) ii) It contains carbon-carbon double bond. (1) b) The intermolecular attractions between polymer chains weaken if there are plasticizer molecules between the polymer chains. (1) c) i) Any two of the following: ydrogen chloride (1) arbon monoxide (1) arbon particles (1) ii) Any two of the following: ydrogen chloride: irritant to the respiratory system / formation of acid rain (1) arbon monoxide: toxic (1) arbon particles: irritant to the respiratory system (1) iii) Any two of the following: ydrogen chloride: installation of scrubbers (1) arbon monoxide: blasting air into the incinerator (1) arbon particles: installation of electrostatic precipitators / blasting air into the incinerator (1)

27 Unit 28 Addition polymers 27 Remarks* Questions often ask about PV. PV is a thermoplastic produced by addition polymerization. Examples of flexible products made of PV floor tiles, shower curtains, raincoats, waterproof coating for folders and bags, insulating tapes and coverings around electrical wires, seat coverings for taxis. Examples of rigid products made of PV drain pipes and bottles.