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CIE Jun 2014 v3 Paper 4 Q3
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![PMT Piperine is the compound responsible for the hot taste of black pepper. piperine Piperine is an amide and can be broken down as follows: OH + HN piperine piperic acid piperidine (a) Suggest reagents and conditions for this reaction.[1] (b) (i) How many stereoisomers are there with the same structural formula as piperic acid (including piperic acid itself)?(ii) Draw the skeletal structure of a stereoisomer of piperic acid, different to the one shown above. (iii) Suggest structures for the compounds that would be formed when piperic acid is treated with an excess of hot concentrated acidi ed KMnO4.UCLES 2014 9701/43/M/J/14 [4] [Turn over<br />
(c) (i) Write the expression for Kw.(ii) Use your expression and the value of Kw in the Data Booklet to calculate the pH of 0.150 mol dm3 NaOH(aq). PMT (iii) The pH of a 0.150 mol dm3 solution of piperidine is 11.9. HN piperidine Suggest why this answer differs from your answer in (c)(ii).(iv) How would you expect the basicity of piperidine to compare to that of ammonia? Explain your reasoning.[5]UCLES 2014 9701/43/M/J/14<br />
(d) 20.0 cm3 of 0.100 mol dm3 HCl was slowly added to a 10.0 cm3 sample of 0.150 mol dm3 piperidine. The pH was measured throughout the addition. (i) Calculate the number of moles of HCl remaining at the end of the addition. PMT (ii) Hence calculate the [H+] and the pH at the end of the addition. moles of HCl =(iii) On the following axes, sketch how the pH will change during the addition of a total of 20.0 cm3 of 0.100 mol dm3 HCl. Mark clearly where the end point occurs. pH =14 pH 10 15 20 volume HCl added / cm3 (iv) From the following list of indicators, put a tick in the box by the side of the indicator most suitable for this titration. indicator pH at which colour changes place one tick only in this column A B C D 0 - 1 3 - 4 11 - 12 13 - 14UCLES 2014 9701/43/M/J/14 [6] [Total: 16] [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/June_2014_v3_QP_-_Paper_4_CIE_Chemistry_A-level_3-0.jpg)
![Page 3 Mark Scheme Syllabus Paper GCE A LEVELMay/June 2014 9701 43 PMT Cl Cu Cl Cl 2- Cl Cl NH [1] + [1] [1] NH Pt or Cl Pt Cl Cl NH [1] [1] [1] [1] [2] [1] [2] [1] [1] (ii) 2+ OH Cu and OH correct 3D structures: octahedral and tetrahedral (iii) Cl Cl Pt or NH both structures geometric or cis-trans (b) (i) Cu(II) is [Ar] 3d Cl Pt Cl NH Cu(I) is [Ar] 3d 10 (ii) Cu(II): d orbitals / subshell are split (in ligand field) and Cu(I): in doing so it absorbs a photon / light no gap in upper orbital / all orbitals are full electron moves from lower to upper orbital or an electron is promoted / excited (c) (i) H = +233.2157.3 + 302.9 = (+) 212 kJ mol 1 ecf (ii) H = 168.6 + 2157.3 = (+)146 kJ mol 1 allow ecf from (c)(i) high T / temperature since H is positive / endothermic [Total: 16] (a) heat in dilute HCl(aq) (or H2SO4(aq)) (b) (i) four isomers [1] [1]Cambridge International Examinations 2014<br />
Page 4 Mark Scheme Syllabus Paper GCE A LEVELMay/June 2014 9701 43 PMT (ii) must be skeletal trans-cis CO (iii) OH cis-trans OH cis-cis OH [1] [1] [1] [1] [1] [1] [1] 2 mol dm 3 [1] [1] [1] [1] [1] + CO or HO C-CO [1] [1] (c) (i) Kw = [H ][OH 3 (ii) In 0.15 mol dm / [OH ] = Kw [H 3 - NaOH, [OH ] = 0.15 mol dm ], so [H ] = 110 14 / 0.15 = 6.6710 14 mol dm 3 pH = -log10[H ] = 13.18 (13.2) ecf from [H (iii) piperidine is a poorer proton acceptor or piperidine is partially ionised (iv) piperidine should be a stronger base/more basic than ammonia because of the electron-donating (alkyl/CH2) groups (d) (i) n(HCl) at start = 0.120/1000 = 2.010 3 mol n(HCl) at finish = 2101.510 = 0.0005/510 3 3 4 mol 3 (ii) this is in 30 cm of solution, so [HCl] at finish = 0.510 /0.030 = 1.6710 pH = log10(1.6710 ) = 1.78 ecf from (d)(i) 2 (iii) pH / vol curve: start at pH 11.9 vertical portion at V = 15 cm levels off at pH 1.8 (iv) indicator is B [Total: 16] (a) three from phenol (secondary) alcohol (primary) amine arene / aryl / benzene 3[1]Cambridge International Examinations 2014<br />](https://learnah.org/wp-content/uploads/2018/08/June_2014_v3_MS_-_Paper_4_CIE_Chemistry_A-level_3-0.jpg)
