1 Factors affecting rates

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Oxford Textbook Pages : 144 - 146, 149 - 151

CGP Revision Guide Pages : 74 - 79

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Show Specification Ref : 3.2.2a, 3.2.2b, 3.2.2c, 3.2.2d

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Question 1 / 5

January 2013 QP – Unit 2 AQA Chemistry A-level_question_1 section a answer all questions in the spaces provided do not write outside the box a figure shows the volume of hydrogen gas collected when a sample of magnesium reacted with an excess of dilute hydrochloric acid the rate of this reaction can be studied by measuring the time it takes for a given volume of hydrogen to be collected figure volume of hydrogen cm a i state the meaning of the term rate of reaction time s mark a ii state and explain what has happened to the rate of this reaction at point w in figure marks wmp jan chem do not write outside the box a iii in terms of collision theory explain why at a fixed temperature the rate of this reaction doubles when the concentration of the hydrochloric acid doubles marks b in a study of the reaction in part a a student referred to activation energy b i state the meaning of the term activation energy mark b ii complete figure by drawing the shape of the reaction profile from reactants to products for an exothermic reaction show the position of the products show and label the activation energy figure energy reactants question continues on the next page marks turn over wmp jan chem do not write outside the box c barium metal reacts very quickly with dilute hydrochloric acid but it reacts more slowly with water c i write an equation for the reaction of barium with water mark c ii a solution containing barium ions can be used to show the presence of sulfate ions in an aqueous solution of sodium sulfate write the simplest ionic equation for the reaction that occurs and state what is observed simplest ionic equation observation marks c iii state one use of barium sulfate in medicine explain why this use is possible given that solutions containing barium ions are poisonous use explanation marks wmp jan chem turn over for the next question do not write on this page answer in the spaces provided turn over wmp jan chem
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Question 2 / 5

June 2010 QP – Unit 2 AQA Chemistry A-level_question_1 section a do not write outside the box answer all the questions in the spaces provided an equation for the equilibrium reaction between hydrogen iodine and hydrogen iodide is shown below a the curve in the diagram below illustrates the reaction profile for this equilibrium reaction without a catalyst h g i g hi g enthalpy h g i g hi g a i draw on the diagram a curve to illustrate the reaction profile for this equilibrium reaction marks with a catalyst a ii use the diagram to deduce whether the formation of hydrogen iodide from hydrogen and iodine is exothermic or endothermic mark a iii state what the diagram suggests about the sum of the bond enthalpies for the reactant molecules compared with the product molecules mark wmp jun chem do not write outside the box a iv in terms of p and q identify the following for this equilibrium without a catalyst a value for the activation energy for the forward reaction a value for the overall enthalpy change for the forward reaction marks b a mixture of h g and i g was allowed to reach equilibrium b i state the effect of a catalyst on the rate of attainment of this equilibrium mark b ii state and explain the effect of an increase in total pressure on the rate of attainment of this equilibrium effect of an increase in pressure on rate explanation marks turn over for the next question turn over wmp jun chem
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Question 3 / 5

June 2013 QP – Unit 2 AQA Chemistry A-level_question_10 section b answer all questions in the spaces provided do not write outside the box ethanol is an important industrial compound a ethanol can be produced by the hydration of ethene the equation for the equilibrium that is established is h c ch g h o g ch ch oh g h kj mol the operating conditions for the process are a temperature of c and a pressure of mpa under these conditions the conversion of ethene into ethanol is a i identify the catalyst used in this process deduce how an overall yield of is achieved in this process without changing the operating conditions marks a ii use your knowledge of equilibrium reactions to explain why a manufacturer might consider using an excess of steam in this process under the same operating conditions marks wmp jun chem do not write outside the box a iii at pressures higher than mpa some of the ethene reacts to form a solid with a relative molecular mass greater than deduce the identity of this solid give one other reason for not operating this process at pressures higher than mpa do not include safety reasons marks b write an equation for the reaction that has an enthalpy change that is the standard enthalpy of formation of ethanol marks c when ethanol is used as a fuel it undergoes combustion c i define the term standard enthalpy of combustion marks question continues on the next page turn over wmp jun chem c ii consider these bond enthalpy data do not write outside the box c h c c c o o o c o o h bond enthalpy kj mol use these data and the equation to calculate a value for the enthalpy of combustion of gaseous ethanol ch ch oh g o g co g h o g marks d gaseous ethanol can be used to convert hot copper ii oxide into copper d i deduce the role of ethanol in this reaction mark d ii draw the structure of the organic compound with mr that is produced in this reaction mark wmp jun chem
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Question 4 / 5

June 2016 QP – Unit 2 AQA Chemistry A-level_question_5 do not write outside the box methanol for use as a fuel can be produced by the reaction of carbon monoxide with hydrogen co g h g ch oh g h kj mol the reaction is typically carried out at c and pa in the presence of a catalyst a figure shows the maxwell boltzmann distribution for a mixture of carbon monoxide and hydrogen at c figure number of molecules energy ea a i sketch a second curve on figure to show the distribution of molecular energies in this mixture at a higher temperature mark a ii explain with reference to both curves in figure how a small change in temperature leads to a large change in the rate of reaction marks wmp jun chem do not write outside the box b both the rate of production and equilibrium yield of methanol are considered when choosing the most appropriate conditions for the operation of this process on an industrial scale b i state and explain the effect of a higher pressure on the equilibrium yield of methanol marks b ii by considering both rate and yield state why the reaction is carried out at a temperature of c rather than at a higher temperature marks turn over for the next question turn over wmp jun chem
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Question 5 / 5

June 2014 QP – Unit 5 AQA Chemistry A-level_question_7 section b answer all questions in the spaces provided do not write outside the box the characteristic properties of transition metals include coloured ions complex formation and catalytic activity a consider the chromium complexes p and q cr h o aq red violet cr h o cl aq green explain with reference to oxidation states and electron configurations why the chromium ions in complexes p and q contain the same number of d electrons you should not consider the electrons donated by the ligands explain in terms of electrons why the complexes are different colours you are not required to explain why the observed colours are red violet and green marks wmp jun chem do not write outside the box b write an equation to show how the co nh aq ion reacts with diaminoethane explain the thermodynamic reasons why this reaction occurs marks question continues on the next page turn over wmp jun chem do not write outside the box c the toxic complex cisplatin is an effective anti cancer drug because it reacts with the dna in cancer cells preventing cell division c i draw the displayed structure of cisplatin on your structure show the value of one of the bond angles at platinum state the charge if any on the complex marks c ii when cisplatin is ingested an initial reaction involves one of the chloride ligands being replaced by water write an equation for this reaction mark c iii suggest how the risk associated with the use of this drug can be minimised mark wmp jun chem do not write outside the box d explain with the aid of equations how and why vanadium v oxide is used in the contact process marks turn over for the next question turn over wmp jun chem
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