Edexcel A Level Chemistry {WCH12} Paper 1_Mark Scheme_2020 | Unit 2: Energetics, Group Chemistry, Halogenoalkanes and Alcohols

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Mark Scheme (Results) October 2020 Pearson Edexcel International Advanced Subsidiary Level In Chemistry (WCH12) Paper 1: Energetics, Group Chemistry, Halogenoalkanes and AlcoholsEdexcel and BTEC... Qualifications Edexcel and BTEC qualifications are awarded by Pearson, the UK’s largest awarding body. We provide a wide range of qualifications including academic, vocational, occupational and specific programmes for employers. For further information visit our qualifications websites at www.edexcel.com or www.btec.co.uk. Alternatively, you can get in touch with us using the details on our contact us page at www.edexcel.com/contactus. Pearson: helping people progress, everywhere Pearson aspires to be the world’s leading learning company. Our aim is to help everyone progress in their lives through education. We believe in every kind of learning, for all kinds of people, wherever they are in the world. We’ve been involved in education for over 150 years, and by working across 70 countries, in 100 languages, we have built an international reputation for our commitment to high standards and raising achievement through innovation in education. Find out more about how we can help you and your students at: www.pearson.com/uk October 2020 Publications Code WCH12_01_2010_MS All the material in this publication is copyright © Pearson Education Ltd 2020General Marking Guidance  All candidates must receive the same treatment. Examiners must mark the first candidate in exactly the same way as they mark the last.  Mark schemes should be applied positively. Candidates must be rewarded for what they have shown they can do rather than penalised for omissions.  Examiners should mark according to the mark scheme not according to their perception of where the grade boundaries may lie.  There is no ceiling on achievement. All marks on the mark scheme should be used appropriately.  All the marks on the mark scheme are designed to be awarded. Examiners should always award full marks if deserved, i.e. if the answer matches the mark scheme. Examiners should also be prepared to award zero marks if the candidate’s response is not worthy of credit according to the mark scheme.  Where some judgement is required, mark schemes will provide the principles by which marks will be awarded and exemplification may be limited.  When examiners are in doubt regarding the application of the mark scheme to a candidate’s response, the team leader must be consulted.  Crossed out work should be marked UNLESS the candidate has replaced it with an alternative response.Using the mark scheme Examiners should look for qualities to reward rather than faults to penalise. This does NOT mean giving credit for incorrect or inadequate answers, but it does mean allowing candidates to be rewarded for answers showing correct application of principles and knowledge. Examiners should therefore read carefully and consider every response: even if it is not what is expected it may be worthy of credit. The mark scheme gives examiners:  an idea of the types of response expected  how individual marks are to be awarded  the total mark for each question  examples of responses that should NOT receive credit. / means that the responses are alternatives and either answer should receive full credit. ( ) means that a phrase/word is not essential for the award of the mark, but helps the examiner to get the sense of the expected answer. Phrases/words in bold indicate that the meaning of the phrase or the actual word is essential to the answer. ecf/TE/cq (error carried forward) means that a wrong answer given in an earlier part of a question is used correctly in answer to a later part of the same question. Candidates must make their meaning clear to the examiner to gain the mark. Make sure that the answer makes sense. Do not give credit for correct words/phrases which are put together in a meaningless manner. Answers must be in the correct context. Quality of Written Communication Questions which involve the writing of continuous prose will expect candidates to:  write legibly, with accurate use of spelling, grammar and punctuation in order to make the meaning clear  select and use a form and style of writing appropriate to purpose and to complex subject matter  organise information clearly and coherently, using specialist vocabulary when appropriate. Full marks will be awarded if the candidate has demonstrated the above abilities. Questions where QWC is likely to be particularly important are indicated (QWC) in the mark scheme, but this does not preclude others.Section A Question Number Answer Mark 1 The only correct answer is C(+121.5) A is incorrect because this is the enthalpy of atomisation of 2 mol of chlorine atoms B is incorrect because the enthalpy of atomisation is endothermic and refers to 2 mol of chlorine atoms D is incorrect because the enthalpy of atomisation is endothermic (1) Question Number Answer Mark 2 The only correct answer is A (exothermic, increases) B is incorrect because in exothermic reactions, temperatures increase C is incorrect because reactions with a negative enthalpy change are not endothermic D is incorrect because reactions with a negative enthalpy change are not endothermic and the temperature increases (1)Question Number Answer Mark 3 The only correct answer is D (water is a good solvent for ionic compounds) A is incorrect because the less open structure of water compared to ice is due to hydrogen bonding B is incorrect because the reduction in density of ice compared to water is due to hydrogen bonding C is incorrect because the expansion of volume of ice compared to water is due to hydrogen bonding (1) Question Number Answer Mark 4 The only correct answer is D (X,Z,Y) A is incorrect because Y has the highest boiling temperature and X will have a boiling temperature below that of the singly branched chain alkane Z B is incorrect because although X has the lowest boiling temperature, Y will have a boiling temperature above that of the singly branched chain alkane, Z C is incorrect because Y has the highest boiling temperature and X has the lowest boiling- - - - - - [Show More]

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