Transcription
Alkanes andHalogenoalkanes
8Do not writeoutside thebox4There are several oxides of nitrogen.4 (a)An oxide of nitrogen contains 25.9% by mass of nitrogen. Determine the empiricalformula of this oxide.(3 marks)(Extra space) .4 (b)Give one reason why the oxide NO is a pollutant gas.(1 mark)4 (c)The oxide NO reacts with oxygen to form nitrogen dioxide. Write an equation for thisreaction.(1 mark)4 (d)Explain how NO is produced in the engine of a motor vehicle.(2 marks)4 (e)Write an equation to show how NO is removed from the exhaust gases in motorvehicles using a catalytic converter.(1 mark)8(08)WMP/Jun10/CHEM1
Do not writeoutside thebox147Chlorine is a useful industrial chemical.7 (a)Chlorine gas is used in the manufacture of chlorine-containing organic compounds.7 (a) (i)Write equations for the following steps in the mechanism for the reaction of chlorinewith ethane to form chloroethane (CH3CH2Cl).Initiation step.First propagation step.Second propagation step.A termination step producing butane.(4 marks)7 (a) (ii) Give one essential condition and name the type of mechanism in this reaction ofchlorine with ethane.Essential condition .Type of mechanism .(2 marks)(14)WMP/Jun10/CHEM2
8Areas outsidethe box willnot be scannedfor marking4 Alkanes are saturated hydrocarbons which can be obtained from crude oil.Pentane is an example of an alkane. A molecule of pentane contains five carbon atoms.4(a)(i) State the meaning of the term saturated and of the term hydrocarbon as appliedto alkanes.Saturated .Hydrocarbon .(2 marks)4(a)(ii) Give the general formula for the alkanes.(1 mark)4(b) Pentane burns completely in oxygen.4(b)(i) Write an equation for this reaction.(1 mark)4(b)(ii) State how the products of this reaction may affect the environment.(1 mark)4(c) Give the name of a solid pollutant which may form when pentane burns incompletelyin air.(1 mark)(08)WMP/Jan10/CHEM1
9Areas outsidethe box willnot be scannedfor marking4(d) One molecule of C9H20 can be cracked to form one molecule of pentane and one otherproduct.4(d)(i) Write an equation for this cracking reaction.(1 mark)4(d)(ii) Suggest a type of compound that can be manufactured from the other product ofthis cracking reaction.(1 mark)4(d) (iii) State why a high temperature is needed for cracking reactions to occur.(1 mark)Question 4 continues on the next pageTurn over (09)WMP/Jan10/CHEM1
104(e) Pentane can react to form the following haloalkane Q.H4Areas outsidethe box willnot be scannedfor marking(e)HBr HHBrCCCCCHHHHClH(i) Name Q.(1 mark)4(e)(ii) State the type of structural isomerism shown by Q and the haloalkane shownbelow.BrHCHH3CCCH3HCClBr.(1 mark)11(10)WMP/Jan10/CHEM1
127Areas outsidethe box willnot be scannedfor marking(a) Consider the following reaction.HHCH3CCH3 KOHBr7(a)CH3CCH3 KBrOH(i) Name and outline a mechanism for this reaction.Name of mechanism .Mechanism(3 marks)7(a)(ii) Name the haloalkane in this reaction.(1 mark)7(a) (iii) Identify the characteristic of the haloalkane molecule that enables it to undergothis type of reaction.(1 mark)(12)WMP/Jan10/CHEM2
137Areas outsidethe box willnot be scannedfor marking(b) An alternative reaction can occur between this haloalkane and potassium hydroxide asshown by the following equation.HCH3CHCH3 KOHCH3CCH2 KBr H2OBrName and outline a mechanism for this reaction.Name of mechanism .Mechanism(4 marks)7(c) Give one condition needed to favour the reaction shown in part (b) rather than thatshown in part (a).(1 mark)7(d) Alkenes can be polymerised to produce poly(alkenes).7(d)(i) State the type of polymerisation that alkenes undergo.(1 mark)7(d)(ii) Name the alkene that gives a polymer with the repeating unit shown below.HCH3CCCH3 HName of alkene .(1 mark)Turn over (13)WMP/Jan10/CHEM212
2310Areas outsidethe box willnot be scannedfor marking(d) The reaction of chlorine with ethene is similar to that of bromine with ethene.Name and outline a mechanism for the reaction of chlorine with ethene to form1,2-dichloroethane, as shown by the following equation.H2CCH2 Cl2ClCH2CH2Cl(5 marks)15END OF QUESTIONS(23)WMP/Jan10/CHEM2
Do not writeoutside thebox12Section BAnswer all questions in the spaces provided.6 (a)There is a risk of gas explosions in coal mines. This risk is mainly due to the presenceof methane. If the percentage of coal-mine methane (CMM) in the air in the mine isgreater than 15%, the explosion risk is much lower. CMM slowly escapes from themine into the atmosphere.Write an equation to show the complete combustion of methane.Suggest one reason why there is a much lower risk of an explosion if the percentageof CMM is greater than 15%.State why it is beneficial to the environment to collect the CMM rather than allowing itto escape into the atmosphere.(3 marks)(Extra space) .(12)WMP/Jun11/CHEM1
Do not writeoutside thebox136 (b)Methane can be obtained from crude oil. Some of this crude oil contains an impuritycalled methanethiol (CH3SH). This impurity causes environmental problems whenburned.Write an equation to show the complete combustion of methanethiol.State why calcium oxide can be used to remove the sulfur-containing product of thiscombustion reaction.State one pollution problem that is caused by the release of this sulfur-containingproduct into the atmosphere.(3 marks)(Extra space).Turn over for the next questionTurn over(13)䊳WMP/Jun11/CHEM16
Do not writeoutside thebox147Pentane is a member of the alkane homologous series.7 (a)Give the general formula for the homologous series of alkanes.(1 mark)7 (b)One of the structural isomers of pentane is 2,2-dimethylpropane.Draw the displayed formula of 2,2-dimethylpropane.State the type of structural isomerism shown.(2 marks)(14)WMP/Jun11/CHEM1
Do not writeoutside thebox157 (c)A molecule of hydrocarbon Y can be thermally cracked to form one molecule ofpentane and two molecules of ethene only.Deduce the molecular formula of Y.State why high temperatures are necessary for cracking reactions to occur.Give one reason why thermal cracking reactions are carried out in industry.(3 marks)(Extra space) .7 (d)Write an equation for the incomplete combustion of pentane to form a solid pollutant.Suggest why this solid pollutant is an environmental problem.(2 marks)(Extra space) .Question 7 continues on the next pageTurn over(15)䊳WMP/Jun11/CHEM1
Do not writeoutside thebox167 (e)Pentane can react with chlorine as shown in the following equation.C5H12 Cl2C5H11Cl HClCalculate the percentage atom economy for the formation of C5H11ClDeduce how many straight-chain isomers of C5H11Cl could be formed.(3 marks)(Extra space).7 (f)Consider the following compound.HHClClHCCCCHHHHHCHHCHHName this compound.Deduce the empirical formula of this compound.(2 marks)13END OF QUESTIONSCopyright 2011 AQA and its licensors. All rights reserved.(16)WMP/Jun11/CHEM1
Do not writeoutside thebox167Halogens are used to make halogenated organic compounds.7 (a)The refrigerant used in air conditioners is a mixture of fluorinated alkanes.These compounds are made by fluorination reactions.The mechanism for the reaction of fluorine with an alkane or with a fluoroalkane is afree-radical substitution similar to the reaction of chlorine with methane.7 (a) (i)Write the overall equation for the reaction of fluorine with methane to formtrifluoromethane (CHF3).(1 mark)7 (a) (ii) Write equations for the following steps in the mechanism for the reaction of fluorinewith trifluoromethane (CHF3) to form tetrafluoromethane (CF4).Initiation step.First propagation step.Second propagation step.A termination step leading to the formation of hexafluoroethane.(4 marks)(16)WMP/Jun11/CHEM2
Do not writeoutside thebox177 (b)Chlorofluorocarbons (CFCs) were used as refrigerants.In the upper atmosphere, ultra-violet radiation breaks bonds in the CFCs to produce areactive intermediate that catalyses the decomposition of ozone.7 (b) (i)An example of a CFC is 1,1,1-trichloro-2,2-difluoroethane.Draw the displayed formula of this CFC.(1 mark)7 (b) (ii) Identify a bond in a CFC that is broken by ultra-violet radiation to produce a reactiveintermediate.Give the name of this reactive intermediate that catalyses the decomposition of ozone.Write an overall equation for this decomposition of ozone.Bond broken .Name of the reactive intermediate .Overall equation.(3 marks)9Turn over for the next questionTurn over(17)䊳WMP/Jun11/CHEM2
Do not writeoutside thebox219Organic reaction mechanisms help chemists to understand how the reactions oforganic compounds occur.The following conversions illustrate a number of different types of reaction mechanism.9 (a)When 2-bromopentane reacts with ethanolic KOH, two structurally isomeric alkenes areformed.9 (a) (i)Name and outline a mechanism for the conversion of 2-bromopentane into pent-2-eneas shown below.ethanolic KOHCH3CH2CH2CHBrCH3CH3CH2CH CHCH3(4 marks)9 (a) (ii) Draw the structure of the other structurally isomeric alkene produced when2-bromopentane reacts with ethanolic KOH.(1 mark)Question 9 continues on the next pageTurn over(21)䊳WMP/Jun11/CHEM2
Do not writeoutside thebox229 (b)Name and outline a mechanism for the following conversion.CH3CH3C CH2Br2CH3CH3CCH2BrBr(5 marks)(22)WMP/Jun11/CHEM2
Do not writeoutside thebox239 (c)Name and outline a mechanism for the following conversion.CH3CH2CH2BrNH3CH3CH2CH2NH2(5 marks)15END OF QUESTIONS(23)WMP/Jun11/CHEM2
Do not writeoutside thebox84Cetane (C16H34) is a major component of diesel fuel.4 (a)Write an equation to show the complete combustion of cetane.(1 mark)4 (b)Cetane has a melting point of 18 oC and a boiling point of 287 oC.In polar regions vehicles that use diesel fuel may have ignition problems.Suggest one possible cause of this problem with the diesel fuel.(1 mark)4 (c)The pollutant gases NO and NO2 are sometimes present in the exhaust gases ofvehicles that use petrol fuel.4 (c) (i)Write an equation to show how NO is formed and give a condition needed for itsformation.Equation .Condition .(2 marks)4 (c) (ii) Write an equation to show how NO is removed from the exhaust gases in a catalyticconverter. Identify a catalyst used in the converter.Equation .Catalyst .(2 marks)4 (c) (iii) Deduce an equation to show how NO2 reacts with water and oxygen to formnitric acid (HNO3).(1 mark)(08)WMP/Jan11/CHEM1
Do not writeoutside thebox94 (d)Cetane (C16H34) can be cracked to produce hexane, butene and ethene.4 (d) (i)State one condition that is used in this cracking reaction.(1 mark)4 (d) (ii) Write an equation to show how one molecule of cetane can be cracked to formhexane, butene and ethene.(1 mark)4 (d) (iii) State one type of useful solid material that could be formed from alkenes.(1 mark)10Turn over for the next questionTurn over(09)䊳WMP/Jan11/CHEM1
Do not writeoutside thebox2Section AAnswer all questions in the spaces provided.1Oxygen and ozone (O3) both occur as gases in the upper atmosphere.Chlorine atoms catalyse the decomposition of ozone and contribute to the formationof a hole in the ozone layer.These chlorine atoms are formed from chlorofluorocarbons (CFCs) such as CF3Cl1 (a) (i)Give the IUPAC name of CF3Cl.(1 mark)1 (a) (ii) Complete the following equation that shows the formation of a chlorine atom from amolecule of CF3ClFFCCl F Cl .(1 mark)1 (a) (iii) State what the represents in Cl .(1 mark)1 (b)Write two equations that show how chlorine atoms catalyse the decomposition ofozone into oxygen.Equation 1 .Equation 2 .(2 marks)(02)WMP/Jan11/CHEM2
Do not writeoutside thebox127 (a)7 (a) (i)The reaction of bromine with propane is similar to that of chlorine with methane.Three steps in the mechanism for the bromination of propane to form 1-bromopropaneare shown below.Step 1Br2 2Br Step 2Br CH3CH2CH3 CH3CH2CH2 Step 3CH3CH2CH2 Br2 CH3CH2CH2Br Br HBrName the type of mechanism in this reaction.(1 mark)7 (a) (ii) Give an essential condition for Step 1 to occur.(1 mark)7 (a) (iii) Name the type of step illustrated by Steps 2 and 3.(1 mark)7 (a) (iv) In this mechanism, a different type of step occurs in which free radicals combine.Name this type of step.Write an equation to show how hexane could be formed from two free radicals in themechanism of this reaction.Type of step .Equation .(2 marks)7 (a) (v) Write an overall equation for the reaction between bromine and propane by the samemechanism to produce octabromopropane (C3Br8).(1 mark)(12)WMP/Jan11/CHEM2
Do not writeoutside thebox137 (b)Bromine reacts with alkenes, even though bromine is a non-polar molecule.7 (b) (i)Explain why bromine molecules react with the double bonds in alkenes.(2 marks)(Extra space) .7 (b) (ii) Name the type of mechanism involved in this reaction.(1 mark)7 (b) (iii) Draw the structure of the compound with Mr 387.6 formed whenpenta-1,4-diene (H2C CHCH2CH CH2) reacts with an excess of bromine.(1 mark)7 (c)Two products are formed when propene reacts with hydrogen bromide.Draw the structure of the intermediate that leads to the formation of the major productin the reaction of propene with hydrogen bromide.Give the name of this type of intermediate.Structure of intermediateType of intermediate .
7 (b) Chlorofluorocarbons (CFCs) were used as refrigerants. In the upper atmosphere, ultra-violet radiation breaks bonds in the CFCs to produce a reactive intermediate that catalyses the decomposition of ozone. 7 (b) (i) An example of a CFC is 1,1,1-trichloro-2,2-difluoroethane. Draw the displayed formula of this CFC. (1 mark)
