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CIE Jun 2016 v3 Paper 4 Q8
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![12 (a) Chromyl chloride, CrO2Cl 2, can be prepared by heating a mixture of potassium dichromate(VI) and potassium chloride with concentrated sulfuric acid. K2Cr2O7 + 4KCl + 3H2SO42CrO2Cl 2 + 3K2SO4 + 3H2O Use the following data to complete the Hess Law cycle and calculate the enthalpy change of the reaction, Hr. PMT compound K2Cr2O7 KCl H2SO4 CrO2Cl 2 K2SO4 H2O enthalpy change of formation, / kJ mol1 2061 437 814 580 1438 286 K2Cr2O7 + 4KCl + 3H2SO4 Hr 2CrO2Cl 2 + 3K2SO4 + 3H2O elements Hr =kJ mol1 [2]UCLES 2016 9701/43/M/J/16<br />
PMT 13 (b) There are two isomeric complex ions with the formula [Cr(NH3)4Cl 2]+. One is green and the other is violet. (i) Suggest the type of isomerism shown by these complex ions.[1] (ii) Explain why these two complex ions are coloured,have different colours.[4] [Total: 7]UCLES 2016 9701/43/M/J/16 [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/June_2016_v3_QP_-_Paper_4_CIE_Chemistry_A-level_8-0.jpg)
![Page 6 Mark Scheme Syllabus Paper Cambridge International AS/A LevelMay/June 2016 9701 43 PMT Answer Marks [2] [1] [1] [4] [1] [1] [1] [1] [1] [Total: 13] [2] [1] Question (a) (i) CH CH CH NH CH CH OH CO (ii) M r = 233 (b) (i) NH2CH(CH2OH)CO2 (ii) F is a DC power supply G is the anode OR positive electrode I is the cathode OR negative electrode H is filter paper (OR gel) soaked in buffer solution (iii) P is NH2CH2CO2 S is [alasergly] or NH2CH2CO2 H or glycine () glycine is the smallest, so travels fastest; tripeptide is the largest, so travels slowest (c) (i) heat with H3O OR heat with OH (aq) (ii) hydrolysis (a) H = [2(580) + 3(286) + 3(1438)][2061 + 4(437) + 3(814)] = 81 kJ mol 1 (b) (i) cistrans OR geometricalCambridge International Examinations 2016<br />
Page 7 Mark Scheme Syllabus Paper Cambridge International AS/A LevelMay/June 2016 9701 43 Question Answer Marks PMT (ii) in a complex the dorbitals are split into 2 energy levels colour is due to absorption of light (in visible region) electron promotion to higher orbital absorbs a photon the dd energy gap is different for the two complexes, hence different colours (a) T is U is CN (b) step 1: C6H5COCl + AlCl 3 (+ heat) step 2: CH3CH2Cl + AlCl 3 (+ heat) step 3: Br2 + light (or heat) step 4: KCN + heat (in ethanol) step 5: H3O OR H in H2O OR HCl (aq) etc AND heat / boil / reflux (c) step 1: electrophilic substitution OR nucleophilic substitution step 5: hydrolysis OR nucleophilic substitution 10 (a) n(MnO4 = 0.0215.2 / 1000 = 3.04105 / 2 = 7.610 4 4 mol (in 25 cm 4 n(C2O4H2) = 3.0410 ) = 3.0410 3 mol in 100 cm Mr = 24 + 64 + 2 = 90 mass of C2O4H2 = 3.0410 = 0.2736 g (0.274) 390 percentage = 0.2736100/40 = 0.68% (b) (i) SOCl 2 or PCl 5 or PClCambridge International Examinations 2016 [1] [1] [1] [1] [Total: 7] [1] [1] [1] [1] [1] [1] [1] [1] [1] [Total: 9] [1] [1] [1] [1]<br />](https://learnah.org/wp-content/uploads/2018/08/June_2016_v3_MS_-_Paper_4_CIE_Chemistry_A-level_8-0.jpg)
