1 Assigning oxidation number

 

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2.1.5 redox Page 1

Oxford Textbook Pages : 48 - 50

CGP Revision Guide Pages : 36 - 37

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Show Specification Ref : 2.1.5a, 2.1.5b, 2.1.5c

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Question 1 / 5

AQA Jan 2012 Paper 2 Q10 consider the five cyclic compounds a b c d and e do not write outside the box cyclohexane cyclohexanol cyclohexanone oh br cyclohexene bromocyclohexane a the infrared spectra of compounds a b c and d are shown opposite write the correct letter a b c or d in the box next to each spectrum you may find it helpful to refer to table on the data sheet wmp jan chem do not write outside the box a i transmittance wavenumber cm mark a ii transmittance wavenumber cm mark a iii transmittance a iv transmittance wavenumber cm mark wavenumber cm question continues on the next page mark turn over wmp jan chem do not write outside the box b a simple chemical test can be used to distinguish between cyclohexane a and cyclohexene d give a reagent for this test and state what you would observe with each compound marks extra space c cyclohexanol b can be converted into cyclohexanone c give a reagent or combination of reagents that can be used for this reaction and state the type of reaction state the class of alcohols to which cyclohexanol belongs marks extra space wmp jan chem d cyclohexane a can be converted into bromocyclohexane e by a reaction that is similar to the reaction of methane either with chlorine or with bromine do not write outside the box name and outline a mechanism for the reaction of methane ch with bromine to form bromomethane ch br give one condition for this reaction to occur write an equation for each step in your mechanism marks extra space end of questions wmp jan chem
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Question 2 / 5

AQA Jan 2012 Paper 2 Q5 do not write outside the box iodine reacts with concentrated nitric acid to produce nitrogen dioxide no a i give the oxidation state of iodine in each of the following i hio marks a ii complete the balancing of the following equation i hno hio no h o mark b in industry iodine is produced from the nalo that remains after sodium nitrate has been crystallised from the mineral chile saltpetre the final stage involves the reaction between nalo and nal in acidic solution half equations for the redox processes are given below io e h l h o l l e use these half equations to deduce an overall ionic equation for the production of iodine by this process identify the oxidising agent overall ionic equation the oxidising agent marks wmp jan chem do not write outside the box c when concentrated sulfuric acid is added to potassium iodide solid sulfur and a black solid are formed c i identify the black solid mark c ii deduce the half equation for the formation of sulfur from concentrated sulfuric acid mark d when iodide ions react with concentrated sulfuric acid in a different redox reaction the oxidation state of sulfur changes from to the reduction product of this reaction is a poisonous gas that has an unpleasant smell identify this gas mark e a yellow precipitate is formed when silver nitrate solution acidified with dilute nitric acid is added to an aqueous solution containing iodide ions e i write the simplest ionic equation for the formation of the yellow precipitate mark e ii state what is observed when concentrated ammonia solution is added to this precipitate mark e iii state why the silver nitrate is acidified when testing for iodide ions mark question continues on the next page turn over wmp jan chem do not write outside the box f consider the following reaction in which iodide ions behave as reducing agents cl aq i aq i aq cl aq f i in terms of electrons state the meaning of the term reducing agent mark f ii write a half equation for the conversion of chlorine into chloride ions mark f iii suggest why iodide ions are stronger reducing agents than chloride ions marks extra space wmp jan chem
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Question 3 / 5

AQA Jan 2013 Paper 2 Q4 do not write outside the box a student used hess s law to determine a value for the enthalpy change that occurs when anhydrous copper ii sulfate is hydrated this enthalpy change was labelled hexp by the student in a scheme of reactions anhydrous copper ii sulfate water hexp hydrated copper ii sulfate h water h water copper ii sulfate solution a state hess s law mark b write a mathematical expression to show how hexp h and h are related to each other by hess s law mark c use the mathematical expression that you have written in part b and the data book values for the two enthalpy changes h and h shown to calculate a value for hexp h kj mol h kj mol mark wmp jan chem do not write outside the box d the student added mol of pure anhydrous copper ii sulfate to cm of deionised water in an open polystyrene cup an exothermic reaction occurred and the temperature of the water increased by c d i use these data to calculate the enthalpy change in kj mol for this reaction of copper ii sulfate this is the student value for h in this experiment you should assume that all of the heat released is used to raise the temperature of the g of water the specific heat capacity of water is j k g marks d ii suggest one reason why the student value for h calculated in part d i is less accurate than the data book value given in part c mark e suggest one reason why the value for hexp cannot be measured directly mark extra space turn over wmp jan chem
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Question 4 / 5

AQA Jun 2012 Paper 2 Q3 do not write outside the box the manufacture of food grade phosphoric acid for use in cola drinks begins with the production of pure white phosphorus from the mineral fluoroapatite ca f po a complete the following equation for the manufacture of phosphorus ca f po sio c casio caf co p mark b as the phosphorus cools it forms white phosphorus p give the oxidation state of phosphorus in each of the following p h po marks c fertiliser grade phosphoric acid is manufactured from sulfuric acid and calcium phosphate use the following precise relative atomic mass data to show how mass spectrometry can be used to distinguish between pure sulfuric acid h so and pure phosphoric acid h po which both have mr to two significant figures atom precise relative atomic mass h o p s mark wmp jun chem do not write outside the box d concentrated phosphoric acid is used as a catalyst in the hydration of propene to form the alcohol ch ch oh ch as the main organic product the industrial name for this alcohol is isopropyl alcohol d i state the meaning of the term catalyst mark extra space d ii state the meaning of the term hydration mark extra space d iii write an equation for the hydration of propene to form isopropyl alcohol give the iupac name for isopropyl alcohol equation iupac name marks turn over wmp jun chem
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Question 5 / 5

AQA Jun 2012 Paper 4 Q7 do not write outside the box a a chemist discovered four unlabelled bottles of liquid each of which contained a different pure organic compound the compounds were known to be propan ol propanal propanoic acid and chloropropane describe four different test tube reactions one for each compound that could be used to identify the four organic compounds your answer should include the name of the organic compound the reagent s used and the expected observation for each test marks extra space wmp jun chem do not write outside the box b a fifth bottle was discovered labelled propan ol the chemist showed using infrared spectroscopy that the propan ol was contaminated with propanone the chemist separated the two compounds using column chromatography the column contained silica gel a polar stationary phase the contaminated propan ol was dissolved in hexane and poured into the column pure hexane was added slowly to the top of the column samples of the eluent the solution leaving the bottom of the column were collected suggest the chemical process that would cause a sample of propan ol to become contaminated with propanone state how the infrared spectrum showed the presence of propanone suggest why propanone was present in samples of the eluent collected first those with shorter retention times whereas samples containing propan ol were collected later marks extra space turn over for the next question turn over wmp jun chem
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