5 DNA

 

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3.13 Amino Acids Proteins And Dna Page 6 - 7

Oxford Textbook Pages : 467 - 470

CGP Revision Guide Pages : 187 - 188

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Show Specification Ref : 3.3.13.4

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Question 1 / 5

AQA Jan 2011 Paper 2 Q8 do not write outside the box a student read the following passage on the internet haloalkanes contain a polar covalent bond the carbon atom of the polar covalent bond can be attacked by nucleophiles nucleophilic attack enables haloalkanes to undergo substitution reactions a nucleophilic substitution reaction occurs when a haloalkane undergoes hydrolysis the rate of hydrolysis of the haloalkane is influenced by the carbon halogen bond enthalpy a explain the meaning of each of the following terms in the information given above a i nucleophile mark a ii substitution as applied to nucleophilic substitution in a haloalkane mark a iii hydrolysis mark a iv bond enthalpy as applied to a carbon halogen bond mark question continues on the next page turn over wmp jan chem do not write outside the box b outline a mechanism for the nucleophilic substitution reaction in which bromopropane ch chbrch reacts with potassium hydroxide to form propan ol c haloalkanes also undergo elimination reactions to produce alkenes c i outline a mechanism for the elimination reaction in which bromopropane reacts with potassium hydroxide to form propene marks marks wmp jan chem c ii a student obtained the following infrared spectrum for the product from this do not write outside the box elimination reaction transmittance wavenumber cm use information from the infrared spectrum to state and explain how the student deduced that the product was an alkene you may find it helpful to refer to table on the data sheet marks extra space turn over for the next question turn over wmp jan chem
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Question 2 / 5

AQA Jun 2010 Paper 2 Q6 the alkene z methylpent ene reacts with hydrogen bromide as shown below do not write outside the box ch ch ch c c ch hbr hbr ch ch br ch ch ch major product p minor product q a i name the major product p mark a ii name the mechanism for these reactions mark a iii draw the displayed formula for the minor product q and state the type of structural isomerism shown by p and q displayed formula for q type of structural isomerism marks a iv draw the structure of the e stereoisomer of methylpent ene mark wmp jun chem do not write outside the box b the infrared spectra of two compounds r and s are shown below r and s have the molecular formula c h and are structural isomers of methylpent ene r is an unsaturated hydrocarbon and s is a saturated hydrocarbon spectrum transmittance wavenumber cm spectrum transmittance wavenumber cm b i identify the infrared spectrum or that represents compound r use information from the infrared spectra to give one reason for your answer you may find it helpful to refer to table on the data sheet r is represented by spectrum reason marks b ii state the type of structural isomerism shown by r and s mark b iii name one possible compound which could be s mark turn over wmp jun chem
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Question 3 / 5

AQA Jun 2012 Paper 2 Q7 do not write outside the box alkenes are useful intermediates in the synthesis of organic compounds a i complete the elimination mechanism by drawing appropriate curly arrows ho h h h ch c c c ch ch ch ch ch chch ch h o br h h br bromohexane hex ene a ii draw structures for the e and z stereoisomers of hex ene e isomer of hex ene z isomer of hex ene marks marks a iii state the meaning of the term stereoisomers marks extra space wmp jun chem do not write outside the box b the equation for the first reaction in the conversion of hex ene into hexan ol is shown below ch ch ch chch ch h so ch ch ch ch oso oh ch ch outline a mechanism for this reaction marks turn over for the next question turn over wmp jun chem
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Question 4 / 5

AQA Jun 2015 Paper 2 Q7 do not write outside the box a propanone can be formed when glucose comes into contact with bacteria in the absence of air a i balance the following equation for this reaction of glucose to form propanone carbon dioxide and water c h o ch coch co h o a ii deduce the role of the bacteria in this reaction mark mark b propanone is also formed by the oxidation of propan ol b i write an equation for this reaction using o to represent the oxidising agent mark b ii state the class of alcohols to which propan ol belongs mark wmp jun chem do not write outside the box c a student determined a value for the enthalpy change when a sample of propanone was burned the heat produced was used to warm some water in a copper calorimeter the student found that the temperature of g of water increased by c when mol of pure propanone was burned in air use the student s results to calculate a value in kj mol for the enthalpy change when one mole of propanone is burned the specific heat capacity of water is j k g marks question continues on the next page turn over wmp jun chem d define the term standard enthalpy of combustion do not write outside the box marks e use the mean bond enthalpy data in table and the equation given below table to calculate a value for the standard enthalpy change when gaseous propanone is burned marks table c h c c c o o h c o o o mean bond enthalpy kj mol ch coch g o g co g h o g wmp jun chem do not write outside the box f suggest two reasons why the value obtained by the student in question c is different from the value calculated in question e marks reason reason turn over for the next question turn over wmp jun chem
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Question 5 / 5

AQA Jun 2016 Paper 4 Q2 do not write outside the box hemiacetals and acetals are compounds formed by the reaction of aldehydes with alcohols such as the reaction of ethanal with ethanol ch cho ch ch oh h c oh och ch a hemiacetal a i use your knowledge of carbonyl mechanisms to suggest the name of the mechanism of this reaction mark a ii outline how an ethanol molecule reacts with an ethanal molecule in the first step of this mechanism include two curly arrows to show the movement of electron pairs marks b the reaction produces a racemic mixture of chiral molecules b i explain the meaning of the term racemic mixture mark b ii state the relationship between two chiral molecules with the same structural formula mark turn over wmp jun chem do not write outside the box c in the presence of an acid catalyst such as dry hydrogen chloride ethanal reacts with an excess of ethanol to form an acetal the overall reaction of ethanal with an excess of ethanol forms an equilibrium mixture as shown all reactants and products are liquids ch cho ch ch oh h c och ch och ch an acetal h o a mixture of mol of ethanal and mol of ethanol was left to reach equilibrium in the presence of dry hydrogen chloride at a given temperature the equilibrium mixture contained mol of the acetal c i calculate the amount in moles of ethanal and of ethanol in this equilibrium mixture marks amount of ethanal mol amount of ethanol mol space for working wmp jun chem do not write outside the box c ii in a different experiment using the same reaction as in part c an equilibrium mixture was established at a given temperature this mixture contained mol of ethanal mol of ethanol mol of the acetal and mol of water in a total volume of cm write an expression for the equilibrium constant kc for this reaction calculate a value for kc at this temperature give units with your answer marks kc calculation d draw the structure of the acetal c h o formed by the reaction of ethanal with ethane diol mark turn over wmp jun chem
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