9 Manganate titration

 

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Oxford Textbook Pages : 368 - 372

CGP Revision Guide Pages : 120 - 121

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Show Specification Ref : 3.2.5.5

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Question 1 / 5

AQA Jan 2010 Paper 2 Q6 consider the following scheme of reactions areas outside the box will not be scanned for marking ch ch ch propane ch ch ch cl chloropropane ch chclch chloropropane ch ch ch oh propan ol ch ch oh ch propan ol propanal propanone a state the type of structural isomerism shown by propanal and propanone mark b a chemical test can be used to distinguish between separate samples of propanal and propanone identify a suitable reagent for the test state what you would observe with propanal and with propanone test reagent observation with propanal observation with propanone marks c state the structural feature of propanal and propanone which can be identified from their infrared spectra by absorptions at approximately cm you may find it helpful to refer to table on the data sheet mark wmp jan chem areas outside the box will not be scanned for marking d the reaction of chlorine with propane is similar to the reaction of chlorine with methane d i name the type of mechanism in the reaction of chlorine with methane mark d ii write an equation for each of the following steps in the mechanism for the reaction of chlorine with propane to form l chloropropane ch ch ch cl initiation step first propagation step second propagation step a termination step to form a molecule with the empirical formula c h marks e high resolution mass spectrometry of a sample of propane indicated that it was contaminated with traces of carbon dioxide use the data in the table to show how precise mr values can be used to prove that the sample contains both of these gases atom c h o precise relative atomic mass marks turn over wmp jan chem
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Question 2 / 5

AQA Jan 2013 Paper 2 Q5 do not write outside the box glucose is an organic molecule glucose can exist in different forms in aqueous solution a in aqueous solution some glucose molecules have the following structure h oh oh oh c o h oh oh a i deduce the empirical formula of glucose mark a ii consider the infrared spectrum of solid glucose transmittance wavenumber cm state why it is possible to suggest that in the solid state very few molecules have the structure shown you may find it helpful to refer to table on the data sheet mark wmp jan chem do not write outside the box b in the absence of oxygen an aqueous solution of glucose can be fermented to produce ethanol for use in alcoholic drinks write an equation for this fermentation reaction give two other essential conditions for the production of ethanol in this fermentation equation condition condition marks c any ethanol present in the breath of a drinker can be detected by using a breathalyser the ethanol is converted into ethanoic acid the breathalyser has negative and positive electrodes a current is measured and displayed in terms of alcohol content the overall redox equation is as follows ch ch oh i o g ch cooh i h o i c i draw the displayed formula for ethanoic acid c ii deduce a half equation for the reduction of atmospheric oxygen to water in acidic solution at one electrode of the breathalyser mark mark c iii deduce a half equation for the oxidation of ethanol in water to ethanoic acid at the other electrode of the breathalyser mark question continues on the next page turn over wmp jan chem do not write outside the box c iv the earliest breathalysers used laboratory chemicals to oxidise the ethanol to ethanoic acid detection was by a colour change identify a reagent or combination of reagents that you would use in the laboratory to oxidise ethanol to ethanoic acid state the colour change that you would expect to see reagent or combination of reagents colour change marks d the fermentation of glucose from crops is the main method for the production of ethanol the product is called bioethanol the european union has declared that bioethanol is carbon neutral d i state the meaning of the term carbon neutral mark extra space d ii other than carbon neutrality state the main advantage of the use of glucose from crops as the raw material for the production of ethanol mark d iii give one disadvantage of the use of crops for the production of ethanol mark wmp jan chem
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Question 3 / 5

AQA Jun 2011 Paper 2 Q6 do not write outside the box the table below shows the structures of three isomers with the molecular formula c h o e pent en ol pentanal isomer h c c c ch oh ch isomer ch ch ch ch isomer c o ch ch ch c o h c a complete the table by naming isomer mark b state the type of structural isomerism shown by these three isomers mark c the compound z pent en ol is a stereoisomer of e pent en ol c i draw the structure of z pent en ol mark wmp jun chem do not write outside the box c ii identify the feature of the double bond in e pent en ol and that in z pent en ol that causes these two compounds to be stereoisomers mark d a chemical test can be used to distinguish between separate samples of isomer and isomer identify a suitable reagent for the test state what you would observe with isomer and with isomer test reagent observation with isomer observation with isomer marks question continues on the next page turn over wmp jun chem e the following is the infrared spectrum of one of the isomers or do not write outside the box transmittance wavenumber cm e i deduce which of the isomers or would give this infrared spectrum you may find it helpful to refer to table on the data sheet mark e ii identify two features of the infrared spectrum that support your deduction in each case identify the functional group responsible feature and functional group feature and functional group marks wmp jun chem turn over for the next question do not write on this page answer in the spaces provided turn over wmp jun chem
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Question 4 / 5

AQA Jun 2013 Paper 2 Q2 do not write outside the box the following pairs of compounds can be distinguished by simple test tube reactions for each pair give a suitable reagent that could be added separately to each compound to distinguish between them describe what you would observe in each case a agbr s and agi s reagent observation with agbr s observation with agi s marks b hcl aq and hno aq reagent observation with hcl aq observation with hno aq marks c cyclohexane and cyclohexene reagent observation with cyclohexane observation with cyclohexene marks wmp jun chem d butanal and butanone do not write outside the box reagent observation with butanal observation with butanone marks turn over for the next question turn over wmp jun chem there are no questions printed on this page do not write on this page answer in the spaces provided wmp jun chem
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Question 5 / 5

AQA Jan 2011 Paper 5 Q7 do not write outside the box hydrogen peroxide is used as an oxidising agent in the preparation of transition metal complexes a consider the following reaction scheme all the complexes are in aqueous solution co h o cobalt ii complex reaction reaction co nh h o a i identify a reagent for reaction and describe the colour change that occurs marks a ii state the colour of the final solution formed in reaction mark wmp jan chem b consider the following reaction scheme all the complexes are in aqueous solution do not write outside the box cr h o chromium iii complex cro reaction h o reaction excess naoh aq b i for reaction state the colour of the initial and of the final solution and write an equation for the reaction marks b ii write a half equation for the reduction of hydrogen peroxide to hydroxide ions deduce an overall equation for reaction and state the colour of the final solution marks question continues on the next page turn over wmp jan chem do not write outside the box c the concentration of a hydrogen peroxide solution can be determined by titration with acidified potassium manganate vii solution in this reaction the hydrogen peroxide is oxidised to oxygen gas a cm sample of the hydrogen peroxide solution was added to a volumetric flask and made up to cm of aqueous solution a cm sample of this diluted solution was acidified and reacted completely with cm of mol dm potassium manganate vii solution write an equation for the reaction between acidified potassium manganate vii solution and hydrogen peroxide use this equation and the results given to calculate a value for the concentration in mol dm of the original hydrogen peroxide solution if you have been unable to write an equation for this reaction you may assume that mol of kmno react with mol of h o this is not the correct reacting ratio marks extra space end of questions wmp jan chem there are no questions printed on this page do not write on this page answer in the spaces provided wmp jan chem there are no questions printed on this page do not write on this page answer in the spaces provided copyright aqa and its licensors all rights reserved wmp jan chem
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