Dynamic Learning is an online subscription solution that supports teachers and students with high quality content and unique tools. Dynamic Learning incorporates elements that all work together to give you the ultimate classroom and homework resource. Teaching and Learning titles include interactive resources, lesson planning tools, self-marking tests and assessment. Teachers can: ● Use the Lesson Builder to plan and deliver outstanding lessons ● Share lessons and resources with students and colleagues ● Track students’ progress with Tests and Assessments Teachers can also combine their own trusted resources alongside those from AQA A-level Chemistry 2 which has a whole host of informative and interactive resources including: ● Engaging animations and online presentations to provide students with clearer explanations ● Interactive tests within each chapter that can be used in class or set as homework ● Numerous stretch and extension materials to encourage higher-attaining students ● Interactive fl ash cards, a table of the correct A-level language and a full glossary of words used in context AQA A-level Chemistry 2 is available as a Whiteboard eTextbook which is an online interactive version of the printed textbook that enables teachers to: ● Display interactive pages to their class ● Add notes and highlight areas ● Add double-page spreads into lesson plans Additionally the Student eTextbook of AQA A-level Chemistry 2 is a downloadable version of the printed textbook that teachers can assign to students so they can: ● Download and view on any device or browser ● Add, edit and synchronise notes across two devices ● Access their personal copy on the move To fi nd out more and sign up for free trials visit: www.hoddereducation.co.uk/dynamiclearning AQA A-level Chemistry 2 Alyn G. McFarland Teresa Quigg Nora Henry 1471807701_AQA_Chemistry_2_CP_ePub.indd 1 19/06/2015 12:51 AQA material is reproduced by permission of AQA. Although every effort has been made to ensure that website addresses are correct at time of going to press, Hodder Education cannot be held responsible for the content of any website mentioned in this book. It is sometimes possible to find a relocated web page by typing in the address of the home page for a website in the URL window of your browser. Hachette UK’s policy is to use papers that are natural, renewable and recyclable products and made from wood grown in sustainable forests. The logging and manufacturing processes are expected to conform to the environmental regulations of the country of origin. Orders: please contact Bookpoint Ltd, 130 Milton Park, Abingdon, Oxon OX14 4SB. Telephone: +44 (0)1235 827720. Fax: +44 (0)1235 400454. Lines are open 9.00 a.m.–5.00 p.m., Monday to Saturday, with a 24-hour message answering service. Visit our website at www.hoddereducation.co.uk © Alyn McFarland and Nora Henry 2015 First published in 2015 by Hodder Education, An Hachette UK Company Carmelite House, 50 Victoria Embankment, London EC4Y ODZ Impression number 5 4 3 2 1 Year 2019 2018 2017 2016 2015 All rights reserved. Apart from any use permitted under UK copyright law, no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, or held within any information storage and retrieval system, without permission in writing from the publisher or under licence from the Copyright Licensing Agency Limited. Further details of such licences (for reprographic reproduction) may be obtained from the Copyright Licensing Agency Limited, Saffron House, 6–10 Kirby Street, London EC1N 8TS. Cover photo © SSilver–Fotolia Illustrations by Aptara Typeset in 11/13 pt ITC Berkeley Oldstyle Std by Aptara, Inc. Printed in Italy A catalogue record for this title is available from the British Library. ISBN 978 1471 807701 807732_FM_AQA_Chemistry_2_i-vi.indd 2 16/06/2015 17:18 Contents Get the most from this book iv Acknowledgements vi 1 Thermodynamics: Born-Haber cycles 1 2 Thermodynamics: Gibbs free energy change, ΔG, and entropy change, ΔS 26 3 Rate equations 43 4 Equilibrium constant K for homogeneous p systems 68 5 Electrode potentials and cells 78 6 Acids and bases 100 7 Properties of Period 3 elements and their oxides 135 8 Transition metals 149 9 Transition metals: Variable oxidation states 175 10 Optical isomerism 192 11 The carbonyl group 198 12 Aromatic chemistry 233 13 Amines 245 14 Polymers, amino acids and DNA 261 15 Organic synthesis, NMR spectroscopy and chromatography 287 16 Maths for chemistry 309 Index 321 QR codes 326 807732_FM_AQA_Chemistry_2_i-vi.indd 3 13/06/15 9:29 am Get the most from this book Welcome to the AQA A-level Chemistry 2 Student’s Book. This book covers Year 2 of the AQA A-level Chemistry specification and all content for the AQA A2 Chemistry specification. The following features have been included to help you get the most from this book. Prior knowledge Thermodynamics: 2 ●● This is a short list of topics that Gchibabnsg efr,e ∆eG e, naenrdg y FAre arecetaaicotsnio.i nTb hthlea eet n ctrahnea lopacycc ucrht aainto gane p oasnrt iictsu loawr nte mis pneorta etunroeu igsh c atoll edde tae rfmeaisnibel e Entropy you should be familiar with before whether or not a reaction will be feasible as some feasible reactions are endothermic. These include: entropy change, ∆S KCl(s) +(aq) → K+ (aq) + Cl− (aq) ΔH 1 = +19 kJ mol−1 starting a chapter. The questions H2O(s) → H2O(l) ΔH 1 = +6 kJ mol−1 H2O(l) → H2O(g) ΔH 1 = +44 kJ mol−1 will help to test your understanding. PRIOR KNOWLEDGE (NH4)2CO3 (s) → 2NH3(g) + CO2(g) + H2O(g) ΔH 1 = +68 kJ mol−1 IEfto nlisleo rewgxiepntegicc atser iedn s tthohamet eYye okauer ya 1 rp ebo oifnaotmks oiolfifa tPrh rewi oiAtrh- Kl eanvlloe owl fCl ethhdeegm ec:iosntrteyn cto oufr Cseh.a Tphteer 4 Adarilesl o fmorduoerrr e.o Tdf ihtshioser sidese trrheeaedc dttihiosanonrs d laieqbruo oivdfe st h haean vpdea sorotnilcuel tetihso ininn gw t hihnei c cshoy msatremem mo n(or re–ea acdntii soionnrc)d.r eeGraeasdese isn ● A positive value for ∆H indicates an endothermic reaction. than solids. ●●● AEeHisn ne nittsnhehsdgaa’eslalppp tLyiyev a ncecwdh hv eaaasnnntlutagg etoeee fs fs fo too htrrfh e ∆aca rHo tro m teuihnatbeedcu itetcsiaonatkinttohee nmans l oapaarynyn f bdcoe ehrxd maocentapahgleteceinrou dmfnloas.rit c oea ndr cel yuha soecinmtni ogtinhc sa.etl a irnneidtaiaacrltd iao nnd ●●Aseynlslt troeofmp tyh.. Temhe s dheogwre ae cohf adnigsoe rfdroerm o ra nra onrddoemrende ssyss itnem a styos ate mmo irse c raalnleddo imts final states. Entropy ● Eusnitnhga lHpey scsh’sa nLgaews. may be calculated from other enthalpy changes Entropy is a measure of disorder within a Entropy is given the symbol S and standard or absolute entropy S 1. system. Entropy is measured in J K−1 mol−1. TEST YOURSELF ON PRIOR KNOWLEDGE 1 Absolute entropy values (standard entropy values) 1 Calcium carbonate decomposes on heating to form calcium oxide and Absolute or standard entropy values are calculated for one mole of a carbon dioxide. Using the standard enthalpies of formation, calculate substance based on a scale where the substance has an entropy value of theC eanCthOa3 l(psy) →cha CnagOe( sfo) r+ t ChiOs2 r(ge)action. 0is (az epreor)f eactt 0c rKy.s Ttahl.is assumes that the crystalline form of the substance at 0 K ∆f H1/kJ mol−1 Some absolute entropy (S 1) values are given in the table: 26 23 aAaCeCCCnc)ma Oaactl4hUccOCmo2Nauh(rsO(gsolladHip)3a)nnni(yt3nsgieg( a)gcg et th )hrh t faoe+eeon a rt5ssgch Ottteteahas2 nfni( eosgwddqr )ar−−–ai utt→e1r36rhha2da93de t0 4oc6 ie 4e7orxtnNinenyotatg.hOnhcea.(atgnlilpo) p tyn+oi e o N6fsfo H2 for(o2gmfrO )mf (o+ng ra3i)mttHirooa2n(gtg ioeo) fnn→ a ,m mc 2aomNlncHoounx3lii(aadgt,)ee wi sath hn−eed9r 2ees kn tteJhtha emam lop l−y1 . Fapsotiriirlagde ciue swkrr ..meh D e2oin.rs1 eoi t Trl ofidkaseelsrlls iyin,s tgt omh a ga osnirvo eeaf tpan dr edoraiibsntalokybr ioglnerat dnothe itsraheenedd AMSNHISC(Cd2iol((a2aig((ssaOslOsC())im)s) (d(lss)(sos)))nd)423175S239.22988814......./0774304 J K−1 mol−1HHCHCNBNLi2Sr22gHaqHOO2(2Cu4(l(5(2l)Nllil)O()(d)laO)Hsq3()(la)q)71717111S1166590516101.0../108 J K−1 mol−1CCONHHNCGlOOa222H22((O(s(2g(gg3gg(e(()))ggg))s))) 11211211S69998310114528395/ J K−1 mol−1 27 NH3(g) −∆4f H61/ kJ mol−1 Tsuhbes htainghcee.r the absolute entropy value, the higher the degree of disorder of a O2(g) 0 From the table it is clear to see that solids are more ordered than liquids and NO(g) + 90 solutions, which are more ordered than gases. This can be used as a general H2O(g) −242 rule to explain changes in entropy later. b) Explain why oxygen has a value of zero. 807701_C02_AQA_Chemistry_2_026-042.indd 26 K27/e05/2015 y15:528 0770t1_C0e2_AQA_Crhemistrym_2_026-042.indsd 27 and formulae 27/05/2015 15:52 These are highlighted in the text and definitions are given in the margin to help you pick out and learn these Tips important concepts. 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oetiio u)ohsitao 1 ofhec lutse nchlas lddeh1lneneq eeel iput lnem leepu tre fr uq riirtam hdtpsfo ib tricdhefuicrn ote ogeo lirfrttl, e 2seaoii lhue as. ovailbleafa u lllsiresstmee mo r eb tgu-mr posshi rq hwtrieucrbouseuofLhigeiu Cear gohumiafeenlymrth eenn il eiehgnemrrill’scr ptgei dr ssianepe.sbct,eoipl l s e o t rsdarosffsaa r ii nfrytnutodot ehoidogtmmefe e aal.es d ssplax eippfodeflenetyt n y tt.sohi eve 157 1471807671_AQA_Chemistry_Ch13.indd 292 PYaoe●●●Ptxof rrautqGdOcPahmaaob uuirwrefmlcceefriae inpie0esn9ctt l/p0t3ntanll/uii2g0ioe e1tcc5 od fe l i1–t 7it–:od 1neee n7y –o1 nn.B4os7dM 1 f8 0tqq,Qa.7 w 6 7e1spo_caAuuuQiviAanrrc_tCeeheaneeeh dmsriq sctdry d tyss_Ctusthii1ie i3ohihi.dtti)e)ncc d mdpn iiep osea ho2o9too3ttayst arsaasisqes it iuonnunptma msuh na cd hrtyssyaesneadensirihodsnrt xdei.tt. cd ogeah i oToulr aoqlenhlotdn u seaue g,es bv rresei eeetnr(c (11ri )gf )oocayoaulbdnnolulllseansoed dwreed wwc)i ) )t dnfmpeoisteher etothogrhthp yayailhhslan acmot-m2m hiaeu-inhtnouele. in h r ugslteddathhl yttl ole ebiliypfe .ge bo leh oeeauxt-sfba ctmttlm hhehci o(ae(se2(2tg(2)02) n)9 io )/0halc3d/2d e0n1et5ai v i 1 f7dn:ds1qfe7ee salutwre thoeee eaisnfsn rtt td is awoyhitlfynoloif tpiusuhc,eru los dlu tbyt .e v 09/03/2015 17:08 A dedicated chapter for developing your Maths can be found at the back of 1471807671_AQA_Chemistry_Ch6.indd 157 this book. 807732_FM_AQA_Chemistry_2_i-vi.indd 5 13/06/15 9:30 am Photo credits The Publisher would like to thank the following for permission to reproduce copyright material: p. 16 Courtesy of Morgan Riley – Wikipedia Commons (http://creativecommons.org/licenses/by/3.0/deed.en); p. 27 both © Hodder Education; p. 27 © Hodder Education; p. 32 © CHARLES D. 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Every effort has been made to trace all copyright holders, but if any have been inadvertently overlooked, the Publisher will be pleased to make the necessary arrangements at the first opportunity. vi 807732_FM_AQA_Chemistry_2_i-vi.indd 6 16/06/2015 17:18 1 Thermodynamics: Born-Haber cycles PRIOR KNOWLEDGE It is expected that you are familiar with all of the content of the Energetics unit in Year 1 of the A-level Chemistry course. The following are some key points of Prior Knowledge: ● The enthalpy change in a chemical reaction is represented by ΔH. ● ΔH is the heat energy change measured under conditions of constant pressure. ● For exothermic reactions, ΔH has a negative value. ● For endothermic reactions, ΔH has a positive value. ● The standard enthalpy change of combustion is the enthalpy change when 1 mole of a substance is burned completely in excess oxygen with all substances in standard states under standard conditions. ● The standard enthalpy change of formation is the enthalpy change when 1 mole of a compound is formed from its constituent elements in their standard states under standard conditions. ● Hess’s Law states that the enthalpy change for a chemical reaction is independent of the route taken and depends only on the initial and final states. ● Hess’s Law can be used to calculate enthalpy changes for chemical reactions from the enthalpy changes of other reactions. ● Temperature changes may be used to calculate enthalpy changes using q = mcΔT. ● The mean bond enthalpy is a measure of the energy required to break one mole of a covalent bond measured in kJ mol−1 averaged across compounds containing that bond. ● Mean bond enthalpy values may be used to calculate the enthalpy change for a chemical reaction by considering the covalent bonds broken (endothermic) and the covalent bonds made during the reaction. TEST YOURSELF ON PRIOR KNOWLEDGE 1 1 Write equations, including state symbols, to represent the standard Key: enthalpies of formation given below: a) Formation of magnesium oxide, MgO(s). 1 b) Formation of hydrogen chloride, HCl(g). 2 Write equations, including state symbols to represent the standard Na enthalpies of combustion given below: a) Combustion of propane, C H (g). 3 8 b) Combustion of methanol, CH OH(l). 3 Cl 807701_C01_AQA_Chemistry_2_001-025.indd 1 13/06/15 8:50 am 3 The standard enthalpies of formation of ethane, carbon dioxide and water are −85, −394 and −286 kJ mol−1, respectively. a) State Hess’s Law. b) Write an equation, including state symbols, to represent the standard enthalpy of combustion of ethane. c) C alculate a value for the standard enthalpy of combustion of ethane. 4 In an experiment the temperature of 200 g of water rose by 22.4 °C when 0.015 mole of ethanol were burned in air and the heat used to warm the water. Calculate a value for the enthalpy change when one mole of ethanol is burned. The specific heat capacity of water is 4.18 J K−1 g−1). 5 The mean bond energy values for certain covalent bonds are given below: Bond Mean bond enthalpy (kJ mol−1) C–H 412 C–C 348 O–H 463 O=O 496 C=O 803 Calculate a value for the following reaction using these values: C H (g) + 5O (g) → 3CO (g) + 4H O(g) 3 8 2 2 2 ●● S Enthalpy changes in ionic compounds E L C Y The changes that occur during the formation of an ionic compound are C R  considered in this unit. The dissociation or formation of an ionic compound E B may be calculated from other values using Hess’s Law in the form of a A H Born-Haber cycle. - N R Notations O B :  ● ΔH represents an enthalpy change. S C ● ΔH is measured under stated conditions, i.e. ΔH is the enthalpy MI 298 change at 298 K and the pressure is 100 kPa. A N Y ● The enthalpy change is the heat energy change at constant pressure. D O ● Standard Enthalpy Values are the ΔH value for enthalpy changes of M specific reactions measured under standard conditions. R E ● Standard conditions are represented by the symbol 1 which is used H    T after ΔH to indicate that an enthalpy changes occurs under standard 1  conditions. ● Standard conditions are 298 K, 100 kPa pressure, all solutions of concentration 1 mol dm−3 and all substances are present in their standard 2 states. 807701_C01_AQA_Chemistry_2_001-025.indd 2 13/06/15 8:50 am