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CIE Nov 2014 v3 Paper 4 Q1
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![Section A Answer all the questions in the spaces provided. PMT (a) Chlorine exists naturally as a mixture of two isotopes, 35Cl and 37Cl , in the abundance ratio of 3 : 1. The mass spectrum of chlorine consists ofve peaks. (i) Suggest the mass numbers for theseve peaks and the identities of the species responsible. mass number formula of species (ii) Predict the ratios of the abundances of the three species with the highest mass numbers. ratio of abundances =[4] (b) Strontium chloride, SrCl 2, can be used to produce a red colour inreworks. (i) Draw the dot-and-cross diagram for strontium chloride. Show outer shell electrons only.UCLES 2014 9701/43/O/N/14<br />
(ii) Use the following data, together with relevant data from the Data Booklet, to calculate a value for the lattice energy of strontium chloride. You maynd it helpful to construct a Born-Haber cycle. PMT electron af nity per mole of chlorine atoms standard enthalpy of atomisation of Sr(s) standard enthalpy of formation of SrCl 2(s) 349 kJ mol1 +164 kJ mol1 830 kJ mol1 lattice energy =kJ mol1 [5] (c) Strontium nitrate, Sr(NO3)2, can also be used to produce a red colour inreworks. (i) Strontium nitrate can easily be prepared from strontium carbonate, SrCO3. Suggest an equation for this preparation of strontium nitrate.(ii) Write an equation for the reaction that occurs when strontium nitrate is heated.[2] (d) Describe and explain the trend in the thermal stabilities of the nitrates of the Group II elements.[3]UCLES 2014 9701/43/O/N/14 [Total: 14] [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/November_2014_v3_QP_-_Paper_4_CIE_Chemistry_A-level_1-0.jpg)
![age e 2 Cam mbr ridg e In nter Que estio on Ma arki ng p poin nt Mar rk S Sche eme nati iona al A A Le evelO Octo ober r/No ovem mbe er 2 2014 4 (a) ) (i (ii (b) ) (i (ii (c) ) (i ide enti ity 35 3 Cl 37 3 Cl 35 C Cl o or Cl 35 m m/e 3 35 3 37 7 70 7 72 7 74 35 37 35, 37, , 70 , 72 2, 74 cor rrect t for rmul lae at l eas st on ne st truc cture e as s a p posit tive ion C Cl C Cl Cl 37 37 Cl 35 Cl 37 C Cl o or 6:1 9:6 co orrec ct ch harg ges co orrec ct el lectr rons La attic e en nerg gy = = H H f(Sr rCl )( (H atom( (Sr) +i1( Sr) + + H H i2(S Sr) + + H H atom m(Cl l) + 2H H +(8 830 )( (+ 1 64 + 54 48 + + 10 060 + 24 42 + + (2349 9)) =21 46 (kJ 1 mol l Sr rCO O3 + 2H HNO O3 Sr r(NO O3)2 + C CO2 2 + H2O OCa ambr ridge e Int terna ation nal E Exam mina ation ns 20 014 PMT PPap per Sy yllab bus 9 970 43 Ma arks 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ea(C Cl)) MMark ks al tota [4] [5]<br />
Page 3 Mark Scheme Syllabus Paper Cambridge International A LevelOctober/November 2014 9701 43 (ii) Sr(NO3)2 SrO + 2NO2 + 0.5 O2 [2] PMT [3] [2] [6] [4] (d) (down the group) nitrates become more stable / require a higher temperature to decompose as size/radius of ion increases OR charge density of ion decreases so polarisation/distortion of anion/nitrate ion/NO3 /NO bond decreases (a) BrO3 + 5Br + 6H3Br2 + 3H2O five correct species correct balancing st (b) (i) [BrO3 ] 1 order and the concentration is x2, rate doubles OR evidence using expt 1 & 4 eg ratios nd [H ] 2 order and the concentration is x2, rate x4 OR evidence using expt 1 & 2 [Br st - ] 1 order and the concentration is x4, rate x4 OR evidence using expt 1 & 3 eg ratios (ii) (Rate =) k [BrO3 ][Br ][H (iii) k = 1.32 3 1 mol dm (a) (i) chromium and copper (ii) (all orbitals have the) same energy (iii) correct id of one higher energy d orbital the other higher energy d orbitalCambridge International Examinations 2014<br />](https://learnah.org/wp-content/uploads/2018/08/November_2014_v3_MS_-_Paper_4_CIE_Chemistry_A-level_1-0.jpg)
