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CIE Nov 2017 v2 Paper 4 Q4
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![An electrochemical cell consists of a half-cell containing V3+(aq) and V2+(aq) ions and another half-cell containing VO2 +(aq) and VO2+(aq) ions. (a) (i) Use data from the Data Booklet to calculate a value for the PMT (ii) Write the ionic equation for the cell reaction. =V [1][1] (iii) Draw a fully labelled diagram of the apparatus you could use to measure the potential of this cell. Include the necessary chemicals. [4]UCLES 2017 9701/42/O/N/17 [Turn over<br />
10 (b) Use data from the Data Booklet to predict whether a reaction might take place when the following pairs of aqueous solutions are mixed. If a reaction occurs, write an equation for it and calculate theV2+(aq) and Sn4+(aq) PMT Does a reaction occur?equationVO2+(aq) and Fe3+(aq) Does a reaction occur?equation[3] [Total: 9]UCLES 2017 9701/42/O/N/17<br />](https://learnah.org/wp-content/uploads/2018/08/November_2017_v2_QP_-_Paper_4_CIE_Chemistry_A-level_4-0.jpg)
![9701/42 Question 3(c)(i) 3(c)(ii) 3(d) Question Cambridge International AS/A LevelMark Scheme PUBLISHED Answer (spectrum of M) contains a broad peak (for OH) at 25003000 cm1 or (spectrum of M) contains peak (for C=O) at 16401750 cm1 or (spectrum of M) lacks (NH2 peak) at 33003500 cm1 5 or 6 peaks OH/NH protons exchange with deuterium or OH / NH + D2OOD / ND + DHO ester and hydrolysed Answer 4(a)(i) Eo cell = 1.00(0.26) = (+)1.26 V 4(a)(ii) VO2 + + V2+ + 2H+VO2+ + V3+ + H2O 4(a)(iii) PMT October/November 2017 Marks 1 1 1 1 Marks 1 1 4 solutions labelled correctly in one half-cell [1] solutions labelled correctly in both half-cells [1] two graphite or platinum electrodes [1] salt bridge and voltmeter [1]UCLES 2017 Page 6 of 12<br />
9701/42 Question 4(b) Question Cambridge International AS/A LevelMark Scheme PUBLISHED AnswerV2+(aq) and Sn4+(aq): yes and Eo 2V2+ + Sn4+2V3+ + Sn2+ [1] cell = +0.15(0.26) = +0.41 V [1]VO2+(aq) and Fe3+(aq) no reaction [1] Answer PMT October/November 2017 Marks 3 5(a) (Na+) 0.095 / 0.181 = 0.525 and octahedral and co-ordination no. = 6 (Mg2+) 0.065 / 0.181 = 0.359 and tetrahedral and co-ordination no. = 4 5(b) 5(c)(i) 5(c)(ii) enthalpy change = (642)(2106) = 430 106 = 147 + 121 + 736 + (349) + lattice energy lattice energy = 761 MgCl2 more exothermic / negative / bigger than MgCl and NaCl more exothermic / negative / bigger than MgCl (reason for MgCl2) higher charge / lower radius of Mg2+ cation (reason for NaCl) smaller radius of Na+ cation 5(d) energy change when 1 mole of atoms / ions each gain an electron or energy change when 1 mole of atoms / ions gain 1 mole of electrons gaseousUCLES 2017 Page 7 of 12 Marks 1 1 3<br />](https://learnah.org/wp-content/uploads/2018/08/November_2017_v2_MS_-_Paper_4_CIE_Chemistry_A-level_4-0.jpg)
