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CIE Jun 2015 v3 Paper 2 Q3
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![A, B, C, D, E and F are all structural isomers with the molecular formula C4H8O. (a) A, B and C all give an orange precipitate when treated with 2,4-DNPH but only A and B give a brick-red precipitate when warmed with Fehlings solution. (i) Draw the skeletal formulae of A, B and C. (ii) Name the type of structural isomerism shown by A and B.[1] (iii) State what you would see when a sample of A is warmed with Tollens reagent.[1] [3]UCLES 2015 9701/23/M/J/15<br />
(b) D, E and F all decolourise bromine and effervesce slowly with sodium metal. E shows geometrical isomerism. Only D has a branched chain. None of these isomers contains an oxygen atom bonded to a carbon atom involved inbonding. None of these isomers contains a chiral centre. (i) Give the structures of D, E and F. Show the two stereoisomers of E and label the stereoisomerism shown.(ii) Identify the gas produced during the reaction of each of these isomers with sodium metal.[1] [5] (c) Another compound, G, C3H6O, contains the same functional group as A. Give equations for the reactions of G with each of acidi ed potassium dichromate(VI) and sodium tetrahydridoborate, NaBH4, using [O] or [H] as appropriate. (i) reaction with acidi ed potassium dichromate(VI) C3H6O +[1] (ii) reaction with NaBH4 C3H6O +[1]UCLES 2015 9701/23/M/J/15 [Total: 13] [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/June_2015_v3_QP_-_Paper_2_CIE_Chemistry_A-level_3-0.jpg)
![Page 3 Question Cambridge International AS/A LevelMay/June 2015 9701 23 Mark Scheme Syllabus Paper Mark Scheme Mark Total (a) (i) Reactivity increases down the group OR reference to observations that indicate trend Outer electrons lost more easily down group Due to increased distance/shielding of outer electrons from nucleus (ii) Mg + 2H2O Mg(OH)2 + H2 (iii) Magnesium hydroxide sparingly soluble/insoluble (iv) Mg + H2O MgO + H2 (b) (i) MgO + 2HNO3 Mg(NO3)2 + H2O (ii) (thermal stability) increases down the group (iii) 2Mg(NO3)2 2MgO + 4NO2 + O2 (iv) N from (+)5 to (+)3 O from 2 to 0 N is reduced and O is oxidised (c) (Very) strong electrostatic attraction/ionic bond High charge (density) of cation and anion/Mg2+ and O2 (d) (i) CaCO3 CaO + CO2 CaO + H2O Ca(OH)2 (ii) 2H+ + CO3 2 CO2 + H2O (iii) 110 48000 = 0.8 mol H+100.1 = mass CaCO3 = 40 g 0.8 (a) (i) A/B = C = (ii) Chain (iii) Silver mirror/ppt/solid (black/grey) [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [3] [1] [1] [1] [1] [1] [1] [3] [2] [2] [1] [2] [19] [1] [1] [1] [1] [1] [3] [1] [1]Cambridge International Examinations 2015<br />
Page 4 Question (b) (i) CH2=C(CH3)CH2OH CH3 CH2 OH trans OR E H2C=CHCH2CH2OH (ii) Hydrogen (c) (i) C3H6O + [O] C3H6O2 (ii) C3H6O +2[H] C3H8O (a) (i) CH3 CH2OH CH3 C CH3 OH OH (ii) CH3 CH3 C O C OHO O C CH3 Cambridge International AS/A LevelMay/June 2015 9701 23 Mark Scheme Syllabus Paper Mark Scheme Mark Total CH3 CH2OH cis OR Z [1] [1+1] [1] [1] [5] [1] [1] [1] [13] [1] [1] [1] [1] [1] [1] [1] [2]Cambridge International Examinations 2015<br />](https://learnah.org/wp-content/uploads/2018/08/June_2015_v3_MS_-_Paper_2_CIE_Chemistry_A-level_3-0.jpg)
