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Edexcel Jan 2013 Paper 4 Q17
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![Question Number 17(a)(i) Question Number 17(a)(ii) Acceptable Answers (KC =) [CH3COOCH2CH3] [H2O] [CH3COOH] [CH3CH2OH] ALLOW C2H5 for CH3CH2 State symbols are not required IGNORE any incorrect state symbols Reject Acceptable Answers Reject Mark Mark (0.20) CH3COOH(l) CH3CH2OH(l) CH3COOCH2CH3(l) H2O(l) Component Equilibrium amount / mol BOTH 0.10 AND 0.20 (1) 0.35 (1) 0.10 and 0.20 scores first mark Allow 0.1 and 0.2 0.35 scores second mark 0.10 0.20 0.35 Reject Concentrations are the same Mark Question Number 17(a)(iii) Units cancel Acceptable Answers OR same number of moles/same number of molecules on each side OR volume / V cancels Ignore statements such as concentrations cancel products and reactants cancel same number of products as reactants Acceptable Answers Question Number 17(a)(iv) KC = (0.20) / V x (0.35) / V (0.20) / V x (0.10) / V = 3.5 / 3.50 Correct answer with or without working scores 1 Ignore omission of V TE from values in (ii) table Reject KC = 4 Acceptable Answers RejectNo effect on (position of) equilibrium (1)Rate (of attainment of equilibrium) is faster / equilibrium reached sooner (1) Question Number 17(b) Mark Mark<br />
Mark Reject Two OH bonds formed in H2O molecule ONLY CO bond broken and made scores (0) overall Reject Heat loss Mark Question Number 17(c)(i) Bonds Broken Acceptable Answers CO and OH (1) Ignore where these bonds are broken in the acid and alcohol molecules. ALLOW COH for CO COH for OH Bonds Made CO and OH (1) Ignore where these bonds are made in the ester and water molecules. ALLOW COC for CO HOH for OH Marks can be awarded by annotating displayed or structural formulae. Comment: Max 1 if any other bonds mentioned Acceptable Answers (CO and OH) bond enthalpies differ in: different environments /different molecules /different compounds OR Bond enthalpies/bond energies are average values ALLOW Bonds being broken and made are attached to different atoms Question Number 17(c)(ii) Question Number 17(d)(i) Acceptable Answers Reject Stotal = R lnK Allow Stotal is proportional to lnK ALLOW Kc or Kp instead of K log instead of ln Stotal is proportional to K / Stotal increases as K increases Mark<br />
Mark Reject If only mentions no effect on position of equilibrium rather than the equilibrium constant Acceptable Answers Question Number *17(d)(ii) First mark: (H = 0 so) Ssurroundings = 0 ORH = 0 T (1) IGNORE Ssurroundings stays the same. Second mark: (so) Stotal does not change OR (so) Stotal = Ssystem (1) Third mark: (As Stotal = R lnK) K does not alter (1) ALLOW it does not alter to assume K does not alter. ALLOW use of Kc or Kp instead of K Each point is stand alone IGNORE justifications in terms of Le Chateliers Principle NOTE: Can award max (1) (i.e. the third scoring point) if the effect on K stated follows on CQ from a change to Stotal<br />
Acceptable Answers Reject CH3COCl + CH3CH2OHCH3COOCH2CH3 + HCl Allow C2H5 for CH3CH2 Allow CH3CO2CH2CH3 for CH3COOCH2CH3 IGNORE missing or incorrect state symbols Acceptable Answers IGNORE Bond angles and length of the lines. CH3CClO/ CH2CH3OH Reject Reject NH2 or CH3 Mark Mark Mark Mark Mark Question Number 17(e)(i) Question Number 17(e)(ii) Question Number 17(f)(i) Question Number 17(f)(ii) Question Number 17(e)(iii) Acceptable Answers IGNORE Other products of the reaction if the above structure has been correctly drawn. Acceptable Answers Reject (CH3COOCH2CH3 + NaOH ) CH3COONa + CH3CH2OH /C2H5OH Allow ionic representations of the sodium salt CH3COO-Na+ IGNORE missing or incorrect state symbols CH2CH3OH for ethanol Acceptable Answers (Reaction with sodium hydroxide is) not an equilibrium / not reversible / goes to completion OR Reverse argument for acid hydrolysis Reject (Total 19 marks)<br />](https://learnah.org/wp-content/uploads/2018/08/January_2013_MS_-_Unit_4_Edexcel_Chemistry_A-level_17-0.jpg)
