1 Enthalpy change

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Oxford Textbook Pages : 72 - 76

CGP Revision Guide Pages : 36 - 37

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Show Specification Ref : 3.1.4.1

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Question 1 / 3

January 2012 QP – Unit 1 AQA Chemistry A-level_question_4 do not write outside the box alkanes are used as fuels a student burned some octane c h in air and found that the combustion was incomplete a i write an equation for the incomplete combustion of octane to produce carbon monoxide as the only carbon containing product mark a ii suggest one reason why the combustion was incomplete mark b catalytic converters are used to remove the toxic gases no and co that are produced when alkane fuels are burned in petrol engines b i write an equation for a reaction between these two toxic gases that occurs in a catalytic converter when these gases are removed mark b ii identify a metal used as a catalyst in a catalytic converter suggest one reason other than cost why the catalyst is coated on a ceramic honeycomb metal reason marks wmp jan chem do not write outside the box c if a sample of fuel for a power station is contaminated with an organic sulfur compound a toxic gas is formed by complete combustion of this sulfur compound c i state one environmental problem that can be caused by the release of this gas mark c ii identify one substance that could be used to remove this gas suggest one reason other than cost why this substance is used substance reason why used marks turn over for the next question turn over 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
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Question 2 / 3

June 2011 QP – Unit 2 AQA Chemistry A-level_question_4 do not write outside the box metals are usually extracted from oxides some of these oxides occur naturally other oxides are made by roasting sulfide ores in air producing sulfur dioxide as a by product for the extraction of some metals the oxide needs to be converted into a chloride a the ore molybdenite contains molybdenum disulfide mos the first stage in the extraction of molybdenum is to roast the ore in air to form molybdenum oxide moo and sulfur dioxide a i write an equation for the first stage in this extraction mark a ii the release of sulfur dioxide into the atmosphere causes environmental problems and wastes a valuable resource identify one environmental problem and identify one use for the sulfur dioxide environmental problem use for sulfur dioxide marks a iii pure molybdenum is formed in the second stage by the reduction of moo using hydrogen write an equation for this reaction mark a iv state one risk in using hydrogen gas in metal extractions mark wmp jun chem do not write outside the box b calcium is an expensive metal it is extracted by the electrolysis of molten calcium chloride b i state why calcium chloride must be molten for electrolysis to occur mark b ii write an equation for the reaction that takes place at the negative electrode during this electrolysis mark b iii identify the major cost in this extraction of calcium mark turn over for the next question turn over wmp jun chem
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Question 3 / 3

June 2015 QP – Unit 5 AQA Chemistry A-level_question_2 do not write outside the box table contains some bond enthalpy data bond bond enthalpy kj mol table h h o o h o a the value for the h o bond enthalpy in table is a mean bond enthalpy state the meaning of the term mean bond enthalpy for the h o bond marks b use the bond enthalpies in table to calculate a value for the enthalpy of formation of water in the gas phase marks wmp jun chem do not write outside the box c the standard enthalpy of combustion of hydrogen forming water in the gas phase is almost the same as the correct answer to question b c i suggest one reason why you would expect the standard enthalpy of combustion of hydrogen to be the same as the answer to question b mark c ii suggest one reason why you would expect the standard enthalpy of combustion of hydrogen to differ slightly from the answer to question b mark turn over for the next question turn over wmp jun chem
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