2 Esterification and hydrolysis of esters

 

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Show Learning Materials

3.9 Carboxylic Acids And Derivatives Page 2 - 3

Oxford Textbook Pages : 416 - 417, 419 - 421

CGP Revision Guide Pages : 164 - 167

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Show Specification Ref : 3.3.9.1

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Question 1 / 5

AQA Jan 2011 Paper 4 Q3 do not write outside the box synthesis gas is a mixture of carbon monoxide and hydrogen methanol can be manufactured from synthesis gas in a reversible reaction as shown by the following equation co g h g ch oh g h kj mol a a sample of synthesis gas containing mol of carbon monoxide and mol of hydrogen was sealed together with a catalyst in a container of volume dm when equilibrium was established at temperature t the equilibrium mixture contained mol of carbon monoxide calculate the amount in moles of methanol and the amount in moles of hydrogen in the equilibrium mixture methanol hydrogen marks b a different sample of synthesis gas was allowed to reach equilibrium in a similar container of volume dm at temperature t at equilibrium the mixture contained mol of carbon monoxide mol of hydrogen and mol of methanol b i write an expression for the equilibrium constant kc for this reaction mark b ii calculate a value for kc for the reaction at temperature t and state its units calculation units marks b iii state the effect if any on the value of kc of adding more hydrogen to the equilibrium mixture mark wmp jan chem do not write outside the box c the temperature of the mixture in part b was changed to t and the mixture was left to reach a new equilibrium position at this new temperature the equilibrium concentration of methanol had increased deduce which of t or t is the higher temperature and explain your answer higher temperature explanation marks d the following reaction has been suggested as an alternative method for the production of methanol co g h g ch oh g h o g the hydrogen used in this method is obtained from the electrolysis of water suggest one possible environmental disadvantage of the production of hydrogen by electrolysis mark e one industrial use of methanol is in the production of biodiesel from vegetable oils such as ch oocc h choocc h ch oocc h give the formula of one compound in biodiesel that is formed by the reaction of methanol with the vegetable oil shown above mark turn over wmp jan chem
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Question 2 / 5

AQA Jun 2010 Paper 4 Q7 section b answer all questions in the spaces provided do not write outside the box esters have many important commercial uses such as solvents and artificial flavourings in foods esters can be prepared in several ways including the reactions of alcohols with carboxylic acids acid anhydrides acyl chlorides and other esters a ethyl butanoate is used as a pineapple flavouring in sweets and cakes write an equation for the preparation of ethyl butanoate from an acid and an alcohol give a catalyst used for the reaction marks wmp jun chem b butyl ethanoate is used as a solvent in the pharmaceutical industry do not write outside the box write an equation for the preparation of butyl ethanoate from an acid anhydride and an alcohol marks c name and outline a mechanism for the reaction of ch cocl with ch oh to form an ester question continues on the next page marks turn over wmp jun chem do not write outside the box d the ester shown below occurs in vegetable oils write an equation to show the formation of biodiesel from this ester ch oocc h choocc h ch oocc h marks wmp jun chem do not write outside the box e draw the repeating unit of the polyester terylene that is made from benzene dicarboxylic acid and ethane diol although terylene is biodegradeable it is preferable to recycle objects made from terylene give one advantage and one disadvantage of recycling objects made from terylene marks turn over for the next question turn over wmp jun chem
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Question 3 / 5

AQA Jun 2013 Paper 4 Q5 do not write outside the box lactic acid ch ch oh cooh is formed in the human body during metabolism and exercise this acid is also formed by the fermentation of carbohydrates such as sucrose c h o a i give the iupac name for lactic acid mark a ii write an equation for the formation of lactic acid from sucrose and water mark b a molecule of lactic acid contains an asymmetric carbon atom the lactic acid in the body occurs as a single enantiomer a racemic mixture racemate of lactic acid can be formed in the following two stage synthesis ch c o stage hcn ch c cn oh stage ch c cooh oh b i name and outline a mechanism for stage name of mechanism mechanism marks wmp jun chem do not write outside the box b ii give the meaning of the term racemic mixture racemate mark b iii explain how you could distinguish between a racemic mixture racemate of lactic acid and one of the enantiomers of lactic acid marks c a mixture of lactic acid and its salt sodium lactate is used as an acidity regulator in some foods an acidity regulator makes sure that there is little variation in the ph of food c i write an equation for the reaction of lactic acid with sodium hydroxide mark c ii the acid dissociation constant ka for lactic acid has the value mol dm at k calculate the ph of an equimolar solution of lactic acid and sodium lactate marks question continues on the next page turn over wmp jun chem do not write outside the box c iii suggest an alternative name for the term acidity regulator explain how a mixture of lactic acid and sodium lactate can act as a regulator when natural processes increase the acidity in some foods name explanation marks extra space d the cup shown is made from pla poly lactic acid pla is the condensation polymer formed from lactic acid the polymer is described as biodegradable and compostable compostable material breaks down slowly in contact with the moist air in a garden bin this produces compost that can be used to improve soil the manufacturers stress that pla cups differ from traditional plastic cups that are neither biodegradable nor compostable d i draw a section of pla that shows two repeating units marks wmp jun chem do not write outside the box d ii name the type of condensation polymer in pla mark d iii an intermediate in the production of pla is a cyclic compound c h o that is formed from two pla molecules draw the structure of this cyclic compound d iv traditional non biodegradable plastic cups can be made from poly phenylethene commonly known as polystyrene draw the repeating unit of poly phenylethene mark mark d v the manufacturers of pla claim that the material will break down to compost in just weeks suggest one reason why pla in landfill may take longer than weeks to break down mark turn over wmp jun chem
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Question 4 / 5

AQA Jun 2015 Paper 4 Q6 do not write outside the box esters are used as raw materials in the production of soaps and biodiesel a a student prepared an ester by two different methods method alcohol acid anhydride method alcohol acyl chloride a i an ester was prepared using method by reacting ch choh with ch co o write an equation for this reaction and give the iupac name of the ester formed marks equation iupac name of the ester a ii the same ester was prepared using method by reacting ch choh with ch cocl outline a mechanism for this reaction marks wmp jun chem do not write outside the box b the ester shown occurs in vegetable oils it can be hydrolysed to make soap and can also be used to produce biodiesel ch oocc h choocc h ch oocc h b i write an equation for the reaction of this ester with sodium hydroxide to form soap marks ch oocc h choocc h ch oocc h b ii give the formula of the biodiesel molecule with the highest mr that can be produced by reaction of this ester with methanol mark turn over for the next question turn over wmp jun chem
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Question 5 / 5

AQA Jun 2016 Paper 4 Q4 do not write outside the box compound x clch cocl is used as a reagent in organic synthesis a the mass spectrum of x contains several molecular ion peaks a i chlorine exists as the isotopes cl and cl in a ratio calculate the m z value of the most abundant molecular ion peak in the mass spectrum of x mark a ii the most abundant fragment ion in the mass spectrum of x has m z draw the displayed formula of this fragment ion mark a iii a molecular ion of x that contains one cl atom and one cl atom undergoes fragmentation to form an ion with m z and one other species write an equation for this fragmentation show which isotope of chlorine is present in each product species marks b one important reaction of x is in the preparation of compound p as shown alcl cl ch c cl ch cl hcl wmp jun chem b i draw the structure of the electrophile formed by the reaction of x with alcl do not write outside the box mark b ii outline the mechanism for the reaction of the electrophile from part b i with benzene in the preparation of p marks c compound q is an alternative product that could be formed when x reacts with benzene cl ch describe how you could distinguish between p and q by a test tube reaction give the reagent used and the observation with each compound marks reagent observation with p observation with q turn over wmp jun chem do not write outside the box d x is also used to make the compound hoch cooh this compound is polymerised to form the polymer known as pga pga is used in surgical sutures stitches d i draw the repeating unit of pga mark d ii production of pga occurs via a cyclic compound two hoch cooh molecules react together to form the cyclic compound and two molecules of water draw the structure of this cyclic compound mark e poly propene is also used in surgical sutures e i draw the repeating unit of poly propene mark wmp jun chem do not write outside the box e ii suggest an advantage of surgical sutures made from pga rather than from poly propene explain your answer marks turn over for the next question turn over wmp jun chem
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