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CIE Mar 2016 v2 Paper 2 Q3
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![Over one million tonnes of hydrogen cyanide, HCN, are produced each year using the Andrussow process. The overall equation for the reaction is shown. CH4(g) + NH3(g) + 1 2 1 O2(g) HCN(g) + 3H2O(g) (a) (i) Draw a dot-and-cross diagram to represent the bonding in a molecule of ammonia, NH3, and state the shape of the molecule. PMT shape of molecule[3] (ii) A molecule of hydrogen cyanide, HCN, is shown. NCH The bonding between the carbon and nitrogen atoms consists of one sigma () bond and two pi () bonds. Sketch the shape of the sigma bond and one of the pi bonds in the space below. Show clearly the position of the atomic nuclei in each diagram. sigma () pi () [2]UCLES 2016 9701/22/F/M/16<br />
PMT (b) The reaction exists as a dynamic equilibrium. (i) Explain what is meant by the term dynamic equilibrium.[1] (ii) State and explain how the amounts of the chemicals present in the equilibrium mixture will change when the pressure is increased.[2] (c) The process uses a platinum catalyst, which increases the rate of reaction. Sketch a Boltzmann distribution on the axes given below and use your diagram to explain how the platinum catalyst increases the rate of the reaction. number of molecules molecular energy[3]UCLES 2016 9701/22/F/M/16 [Turn over<br />
PMT (d) The reaction of hydrogen cyanide with propanone is an important first step in many organic syntheses. (i) Give the full name of the mechanism of this reaction.[1] (ii) Complete the diagram to show the mechanism of the reaction of hydrogen cyanide with propanone. Draw the structure of the intermediate and the product of the reaction. Include all relevant charges, partial charges, curly arrows and lone pairs. H3C CN CH3 [5] [Total: 17]UCLES 2016 9701/22/F/M/16<br />
PMT Question 4 starts on the next page.UCLES 2016 9701/22/F/M/16 [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/March_2016_v2_QP_-_Paper_2_CIE_Chemistry_A-level_3-0.jpg)
![Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A LevelMarch 2016 9701 22 PMT Answer Mark Total [1] [1] [2] [1] [2] [2] [10] [3] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] Question (iii) (ii)=3.2810 250 25.00 2(mol) (iv) r of FeCO3 =55.8 + 12.0 + 3(16.0) = 115.8 (v) (iii)M r(FeCO3) =3.79 g (iv) 5.00 100% = 75.9% (b) (i) 2Fe + Sn2Fe + Sn 3+ 2+ 2+ 4+ species balancing (ii) SnCl 2(aq) + 2HgCl 2(aq) SnCl 4(aq) + Hg2Cl 2(s) SnCl 2 AND 2 state symbols (a) (i) three bonding pairs lone pair AND octet shape = (trigonal) pyramidalCambridge International Examinations 2016<br />
age e 4 Ca amb brid ge Inte erna ation nal AS/ /A L Leve elMar rk S Sche eme Qu uest tion A Answ wer (ii) ( (b) (i) sig gma a() bon nd pi( () b bon forw ward d an nd b back kwar rd re eact tion OR s oc ccur rring g at sam me r rate the e rate e of f forw war rd an nd b back kwa ard r eac ction ns ar re e equa al (ii) M1 M2 = d decr reas sed y yield d of f pro oduc cts / less s pro odu cts form med d / o ra = le eft-h hand d sid de h has few wer m mole es o of ga as OR equ uilib rium m sh hifts to t the l left PMT PPap per Sy yllab bus Ma arch h 20 16 9 970 22 MMark k TTota al [1] [1] [1] [1] [1] [2] [1] [2]Ca ambr ridge e Int terna ation nal E Exam mina ation ns 20 016<br />
Page 5 Mark Scheme Syllabus Paper Cambridge International AS/A LevelMarch 2016 9701 22 Answer Mark Total PMT Question (c) number of mol ecul es Ea with catalystt E a without catalystt molecularrenergyy [1] [1] [1] [3] M1 = correct Boltzmann curve M2, M3 any 2 from: line for both Ea values or statement in text that catalyst lowers Ea (catalyst) increases proportion/number of molecules/particles with energyactivation energy so more frequent successful collisionsCambridge International Examinations 2016<br />
Page 6 Mark Scheme Syllabus Paper Cambridge International AS/A LevelMarch 2016 9701 22 Question Answer Mark Total (d) (i) nucleophilic addition [1] [1] PMT (ii) correct dipole on carbonyl curly arrow from lone pair on CN AND from C=O to O correct intermediate curly arrow from lone pair on O to H correct product [1] [1] [1] [1] [1] [5] [17] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [2] (a) (i) C4H10 (ii) C4H9 (iii) (b) C8H18 + 12O28CO2 + 9H2O (c) sulfur dioxide would be produced on combustion (which contributes to) acid rainCambridge International Examinations 2016<br />](https://learnah.org/wp-content/uploads/2018/08/March_2016_v2_MS_-_Paper_2_CIE_Chemistry_A-level_3-0.jpg)
