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Edexcel Jan 2010 Paper 1 Q19
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![PMT Reject Mark Acceptable Answers Left hand arrow, pointing down, labelled Hc hex-1-ene + Hc hydrogen/ -4003-286/-4289 OR Pointing up with signs given above reversed (1) Right hand arrow pointing down labelled Hc hexane / -4163 OR Pointing up with signs given above reversed (1) Ignore oxygen on both arrows Arrows may be labelled H1 etc if key given or use of numbers in calculation makes this obvious. (Hreaction4163 = -4003286 / or words applying Hess law correctly) Hreaction = -126 however obtained(1) TE: If arrows point up and signs are not reversed Hreaction = +126 Max (1) Acceptable Answers Reject Same (number and type of) bonds are broken and made in each reaction / one C=C (and one H-H) are broken and two C-H made ALLOW reaction is CH=CH- + H2-CH2-CH2- each time (Similar energy change) as in each case H2 reacts with C=C All are alkenes going to alkanes all have the same double bond which reacts in the same way Acceptable Answers Reagent: chlorine/ Cl2 (1) Condition: uv/ sunlight (1) ALLOW light Mark independently Ignore reference to temp and pressure if given with uv light. If answers reversed/both on one line 1 out of 2 Reject Cl Just heat Acceptable Answers (free) radical (1) Substitution (1) Mark independently Reject Mark Mark Mark Question Number 18 (d) (ii) Question Number 18 (d) (iii) Question Number 19 (a) (i) Question Number 19 (a) (ii)<br />
Question Number 19 (b) (i) Acceptable Answers Hydrogen chloride / HCl Question Number 19 (b) (ii) Curly (not half headed) arrow from C=C to H (1) Acceptable Answers Curly arrow from bond in H-Cl to Cl (1) Curly arrow from Cl- to C+ (1) Partial charges on HCl not required Lone pairs on Cl- not required It should be clear if arrows are to/ from a bond or an atom, but give allowance for precise position Correct intermediate without arrows (1) Correct addition of HBr max 2 Correct addition of HCl to propene max 2 Max 2 for addition of Cl2 instead of HCl (forming 1,2 - dichloroethane) Max 1 for addition of Cl2 instead of HCl forming chloroethane Reject Hydrochloric acid Chlorine HCl (aq) Cl2 Reject Attack by Cl- or Cl loses 3rd mark only Correct free radical mechanism from ethane and chlorine scores 0 PMT Mark Mark Mark Acceptable Answers Reject Higher atom economy from ethene /by electrophilic addition Higher yield from ethene Both correct for (1) From ethene only one product / all atoms are used making product /no unwanted products (1) For ethene yield high as no di-, tri- etc substituted products form /only one product / no by-products OR no side reactions occur OR no C4 compounds can form (1) [Or reverse argument] Not much product is lost Question Number 19 (c)<br />
Question Number 19 (d) (i) Acceptable Answers Reject Mark PMT Double bond and electrons around C correct (1) Other electrons correct (1) Can be all dots or all crosses First mark can be given if C2H4 drawn correctly Second mark can be given if C2H5Cl drawn correctly Dont penalise if bonds shown as well as electrons Acceptable Answers Reject Formula not displayed One monomer unit shown in bracket with the number 2 outside bracket Cl on C1 and C2 Cl onC3 and C4 ALLOW H and Cl below C chain; Cl on C2 and C3 or C1 and C4; formula above with brackets at each end and n outside end bracket End bonds should be shown, but dont penalise if these dont go through brackets H atoms should be shown Mark Question Number 19 (d) (ii)<br />
Any 2 Answers could consider the following factors:energy for manufactureavailability / abundance of raw materialslifetime of product/ how often will it need to be replaced /metal rusts/plastic more easily punctured etc recyclable material biodegradable? Is it from a non-renewable resource?ease of recycling /steel an excellentconsequences of disposal / is itAtom economy in manufacture Allow answers comparing specific properties (if correct) illustrating the relevant property Examples PVC will last longer than iron due to lack of corrosion (1) PVC comes from oil which is non-renewable (1) PVC and metals come from non-renewable sources (1) Credit any two valid points Ignore if other answers given: cost PVC biodegradable its carbon footprint Is it environmentally friendly? Pollution comments without reference to resources needed to clean up Question Number Acceptable Answers Reject 19 (d) (iii) QWC PMT Mark<br />](https://learnah.org/wp-content/uploads/2018/08/January_2010_MS_-_Unit_1_Edexcel_Chemistry_A-level_19-0.jpg)
