AQA Jan 2012 Paper 2 Q9 (with explained solutions) |

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AQA Jan 2012 Paper 2 Q9

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section b do not write outside the box answer all questions in the spaces provided three different ways of producing ethanol are shown below reaction reaction c h o glucose ethanol bromoethane ch ch oh ch ch br reaction h c ch ethene a reaction produces a aqueous solution of ethanol it is claimed that the ethanol produced in this way is a carbon neutral biofuel write an equation for reaction and name the process write an equation for the complete combustion of ethanol explain why the ethanol produced by this process may not be a carbon neutral biofuel marks extra space question continues on the next page turn over wmp jan chem do not write outside the box b give a reagent and conditions for reaction reaction ch ch br ch ch oh name and outline a mechanism for reaction suggest one reason other than safety why this method is not used in industry to make ethanol marks extra space wmp jan chem do not write outside the box c reaction is used in industry reaction h c ch ch ch oh identify a suitable catalyst for reaction identify the type of reaction give two conditions in addition to the presence of a catalyst necessary for reaction to produce a high yield of ethanol marks extra space turn over for the next question turn over wmp jan chem

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question a mark scheme general certificate of education a level chemistry unit chemistry in action january marking guidance m c h o ch ch oh co c h oh m fermentation m ch ch oh o co h o c h oh m a specified process e g planting harvesting transport extracting sugar distilling ethanol solution fertiliser production etc m the specified process uses burns fossil fuel that releases co mark comments mark independently for m and m ignore state symbols and credit multiples for m and m penalise c h o once only for m releases increases carbon emissions is insufficient as an alternative to releases co b mark scheme general certificate of education a level chemistry unit chemistry in action january m sodium or potassium hydroxide naoh koh m depends on correct m warm heat reflux and aqueous or aq or water m nucleophilic substitution nb the arrows here are double headed m must show an arrow from the lone pair of electrons on the oxygen atom of the negatively charged hydroxide ion to the c atom m must show the movement of a pair of electrons from the c br bond to the br atom mark m independently provided it is from their original molecule for m and m award full marks for an sn mechanism m one statement from the yield is very low not a high yield or elimination occurs ethene formed the rate of reaction slow bromoethane has to be manufactured made first bromoethane is expensive mark on to m from hydroxide ion ignore oh if koh oh for m ignore dilute for m penalise t oc acidified koh naoh or h so with koh naoh loses m and m for m both words required penalise m if covalent naoh koh is used penalise one mark from m or m if half headed arrows are used penalise m for formal charge on c of the c br or incorrect partial charges on c br penalise once only for a line and two dots to show a bond for m and m maximum of marks if wrong reactant is used penalise m if an extra arrow is drawn from the br of the c br bond to for example k do not penalise the use of sticks for m ignore references to other costs and expenses mark scheme general certificate of education a level chemistry unit chemistry in action january c m concentrated phosphoric acid conc h po or concentrated sulfuric acid conc h so m hydration or electrophilic addition for m and m any two from excess ethene or excess steam water h o or remove the ethanol as it forms or recycle the ethene specified pressure atm p atm or kpa p kpa or mpa p mpa or oc t oc or k t k the ranges given here hightemperature unless they give a value that is not in answers in any order ignore reference to support medium in m do not apply the list principle to these three chosen criteria in m and m accept a reference to low temperature if they specify a correct temperature range or a correct temperature in the range

Question 1 2 3 4 5 6 7 8 9 10

Topics to revise

AQA > Physical chemistry > Equilibrium AS >

2 Industrial processes

AQA > Physical chemistry > Energetics and kinetics AS >

5 Kinetics

AQA > Physical chemistry > Equilibrium AS >

1 Dynamic equilibrium and factors affecting equilibrium

AQA > Inorganic chemistry > Transition metals >

10 Catalysis

AQA > Organic Chemistry > Carboxylic acids and derivatives >

2 Esterification and hydrolysis of esters

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