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CIE Jun 2016 v3 Paper 2 Q3
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![Crude oil is a mixture of hydrocarbons and provides many useful chemicals when processed. Two of the stages involved in the processing of crude oil are fractional distillation and cracking. (a) The diagram is a simplified representation of a fractional distillation column. PMT fraction A fraction B fraction C fraction D fraction E fraction F crude oil in (i) What has to be done to the crude oil before it enters the column?[1] (ii) What trend in structure is there from fraction A to fraction F?[1] (iii) State the trends in two properties of the fractions from A to F.[2] (b) The naphtha fraction from fractional distillation of crude oil is used as a starting material for cracking. (i) Write an equation for the cracking of C12H26 to form the products ethene and one other hydrocarbon in a 2 : 1 mole ratio.[1]UCLES 2016 9701/23/M/J/16<br />
PMT (ii) Suggest a use for each of the products from your equation in (i). Explain what makes each product from (i) suitable for the use you suggest. use of etheneexplanationuse of other productexplanation[4] (c) Burning hydrocarbons can cause a number of environmental problems. The products of internal combustion engines can include oxides of nitrogen and oxides of carbon. Sulfur dioxide is a by-product of burning coal in power stations. (i) Explain how and why oxides of nitrogen are produced in internal combustion engines.[2] (ii) Write an equation for the reaction between nitrogen monoxide and carbon monoxide in a catalytic converter.[1] (iii) Write equations to show the involvement of nitrogen monoxide in the formation of acid rain from atmospheric sulfur dioxide.[3] (iv) Describe two of the problems associated with acid rain.[2]UCLES 2016 9701/23/M/J/16 [Total: 17] [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/June_2016_v3_QP_-_Paper_2_CIE_Chemistry_A-level_3-0.jpg)
![Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A LevelMay/June 2016 9701 23 Question Mark Scheme Mark Total PMT (iv) production of ammonia is exothermic / (forward) reaction exothermic position of eqm would move to left / reverse / reduce yield (at higher T) (c) 4NH3 + 5O24NO + 6H2O N changes from 3 to +2 (so oxidation) O changes from 0 to 2 (so reduction) (d) (i) (+) (ii) shape = tetrahedral angle = 109109.5 (e) eutrophication / algal bloom / stimulates growth of algae (bacteria) use up oxygen when decomposing the plants / algae block light for plants so less oxygen produced aquatic life / fish die (due to lack of oxygen) (a) (i) vaporise / boil / turn to gas (ii) increasing molecular size / no of carbon atoms per molecule / length of carbon chain (iii) increasing b.pt / decreasing volatility increasing viscosity increasing density increasing depth of colour decreasing flammability / decreasing cleanliness of flame owtte [2] [3] [1] [1] [1] [1] [1] [1+1] [2] [1] [1] [2] [1] [max 3] [1] [1] [1] [19] [1] [1] [1] [1] [1] [1] [2] (b) (i) C12H262C2H4 + C8H18 [1] [1]Cambridge International Examinations 2016<br />
Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A LevelMay/June 2016 9701 23 Question Mark Scheme Mark Total PMT (ii) ethene use = making polythene / plastic / polymers feature of ethene = double bond / unsaturated octane / alkane use = fuel / petrol feature of octane / alkane = flammability / releases energy when burned / combusted (c) (i) (produced by) reaction of (atmospheric) oxygen and nitrogen due to high temperature / engine provides energy / combustion provides energy (ii) 2NO + 2CON2 + 2CO2 / NO + CON2 + CO2 (iii) NO + O2NO2 NO2 + SO2SO3 + NO SO3 + H2OH2SO4 / 2H + SO4 / H + HSO4 2 (iv) lowers pH of rivers / lakes / kills fish leaches (toxic) aluminium from soil (into rivers / lakes) leaches away soil nutrients damage to buildings / statues / trees / plants / crops ocean acidification / damage to coral (a) 3-hydroxybutan(-2-)one (b) H2 / Cr2O7 2 or names heat / reflux / warm (c) (i) absorption at 16701740 C (=) O absorption at 28503000 C (-) H absorption at 32003650 O (-) HCambridge International Examinations 2016 [1] [1] [1] [1] [1] [1] [4] [2] [1] [1] [3] [1] [1] [1] [1] [max 2] [1] [1] [1] [1] [17] [1] [1] [1] [2] [1] [1] [1] [1] [3]<br />](https://learnah.org/wp-content/uploads/2018/08/June_2016_v3_MS_-_Paper_2_CIE_Chemistry_A-level_3-0.jpg)
