mtg-chemistry-gr-12-web.pdf

i e n c e Pa r t 2 Grade Physical Sc Chemistry 12 Study Guide Colour Diagrams: Acid-base Indicators* * Refer to page 136 © Department of Basic Education 2015 This content may not be sold or used for commercial purposes. Curriculum and Assessment Policy...

i e n c e Pa r t 2 Grade Physical Sc Chemistry 12 Study Guide Colour Diagrams: Acid-base Indicators* * Refer to page 136 © Department of Basic Education 2015 This content may not be sold or used for commercial purposes. Curriculum and Assessment Policy Statement (CAPS) Grade 12 Mind the Gap study guide for Physical Science Part 2: Chemistry ISBN 978-1-4315-1937-8 This publication has a Creative Commons Attribution NonCommercial Sharealike license. You can use, modify, upload, download, and share content, but you must acknowledge the Department of Basic Education, the authors and contributors. If you make any changes to the content you must send the changes to the Department of Basic Education. This content may not be sold or used for commercial purposes. For more information about the terms of the license please see: http://creativecommons.org/licenses/by-nc-sa/3.0/. Copyright © Department of Basic Education 2015 222 Struben Street, Pretoria, South Africa Contact person: Dr Patricia Watson Email: [email protected] Tel: (012) 357 4502 http://www.education.gov.za Call Centre: 0800202933 The first edition, published in 2012, for the Revised National Curriculum Statement (RNCS) Grade 12 Mind the Gap study guides for Accounting, Economics, Geography and Life Sciences; the second edition, published in 2014 , aligned these titles to the Curriculum and Assessment Policy Statement (CAPS) and added more titles to the series in 2015, including the CAPS Grade 12 Mind the Gap study guide for Physical Science Part 2: Chemistry ISBN 978-1-4315-1937-8 Mind the Gap team Series managing editor: Dr Patricia Watson Production co-ordinators: Lisa Treffry-Goatley and Radha Pillay Production assistants: Nomathamsanqa Hlatshwayo and Motshabi Mondlane Authors: Physical Science: Mariaan Bester, Nkosinathi Michael Khathi, Karen Yvonne Kornet, Jenny Koster, Mosala Daniel Leburu, Karen Reynecke, Lerato Mabogatsu Mphachoe, Thabiso Precious Ndaba, Gilberto Izquierdo Rodriguez, Meshack Jabu Sithole, Kumar Kuttan Pillai Suresh, Sehubedu Jerry Tladi Expert readers: Morongwa Masemolo, Prof Mundslamo Fathuwani, Dr T.D.T Sedumedi, Veena Maharaj, John Ostrowick, Karen van Niekerk Proofreaders: John Ostrowick, Sehubedu and Angela Thomas Designers: Sonja McGonigle and Erika van Rooyen Illustrators: Michele Dean, Vusi Malindi, Khosi Pholosa, John Ostrowick, Kenneth Tekane Cover illustration: Alastair Findlay Afrikaans Translation: Johan Steenkamp Onsite writers’ workshop IT support: Wayne Cussons Special thanks to Winning Teams, CEO Denzil Hollis, for the organisation’s subject expertise and workshop support. Winning Teams board game facilitators: Mantse Khoza and Sue Jobson  © Department of Basic Education 2015 Ministerial foreword The Department of Basic Education (DBE) has pleasure in releasing the second edition of the Mind the Gap study guides for Grade 12 learners. These study guides continue the innovative and committed attempt by the DBE to improve the academic performance of Grade 12 candidates in the National Senior Certificate (NSC) examination. The study guides have been written by teams of exerts comprising teachers, examiners, moderators, subject advisors and coordinators. Research, which began in 2012, has shown that the Mind the Gap series has, without doubt, had a positive impact on grades. It is my fervent wish that the Mind the Gap study guides take us all closer to ensuring that no learner is left behind, especially as we celebrate 20 years of democracy. Matsie Angelina Motshekga, MP The second edition of Mind the Gap is aligned to the 2014 Curriculum and Minister of Basic Education Assessment Policy Statement (CAPS). This means that the writers have considered the National Policy pertaining to the programme, promotion requirements and protocols for assessment of the National Curriculum Statement for Grade 12 in 2014. The CAPS aligned Mind the Gap study guides take their brief in part from the 2013 National Diagnostic report on learner performance and draw on the Grade 12 Examination Guidelines. Each of the Mind the Gap study guides defines key terminology and offers simple explanations and examples of the types of questions learners can expect to be asked in an exam. Marking memoranda are included to assist learners to build their understanding. Learners are also referred to specific questions from past national exam papers and examination memos that are available on the Department’s website – www.education.gov.za. The CAPS editions include Accounting, Economics, Geography, Life Sciences, Mathematics, Mathematical Literacy and Physical Sciences Part 1: Physics and Part 2: Chemistry. The series is produced in both English and Afrikaans. There are also nine English First Additional Language (EFAL) study guides. These include EFAL Paper 1 (Language in Context); EFAL Paper 3 (Writing) and a guide for each of the Grade 12 prescribed literature set works included in Paper 2. These are Short Stories, Poetry, To Kill a Mockingbird, A Grain of Wheat, Lord of the Flies, Nothing but the Truth and Romeo and Juliet. (Please remember when preparing for EFAL Paper 2 that you need only study the set works you did in your EFAL class at school.) The study guides have been designed to assist those learners who have been underperforming due to a lack of exposure to the content requirements of the curriculum and aim to mind-the-gap between failing and passing, by bridging the gap in learners’ understanding of commonly tested concepts, thus helping candidates to pass. All that is now required is for our Grade 12 learners to put in the hours required to prepare for the examinations. Learners, make us proud – study hard. We wish each and every one of you good luck for your Grade 12 examinations. _______________________________ Matsie Angelina Motshekga MP Minister of Basic Education 2015 © Department of Basic Education 2015  © Department of Basic Education 2015 Table of contents Dear Grade 12 learner................................................................viii How to use this study guide.........................................................ix Top 10 study tips............................................................................x Mnemonics.....................................................................................xi Mind maps.....................................................................................xii On the day of the exam..............................................................xiii Question words to help you answer questions........................ xiv Vocabulary..................................................................................... xv General terms............................................................................... xv Technical terms......................................................................... xviii The maths you need................................................................ xxxiv Resource sheets..........................................................................xlii Formulas...................................................................................... xliv Standard reduction potentials................................................... xlv Unit 1: Organic compounds and macromolecules.................. 1 1.1 Organic compounds..................................................................... 1 1.2 Physical properties and structure............................................. 15 1.3 Physical properties of organic compounds............................... 18 1.4 Factors that have an influence on the physical properties of organic compounds................................................................ 19 1.5 Solids, liquids and gases........................................................... 24 1.6 Chemical properties of organic compounds............................. 25 1.7 Reactions of organic compounds.............................................. 29 1.8 Reactions of different homologous series................................ 31 1.9 Creating one hydrocarbon from another................................... 37 1.10 Plastics and polymers................................................................ 40 1.11 Plastics and pollution................................................................. 46 Unit 2: Rate and extent of reactions........................................49 2.1 Summary..................................................................................... 49 2.2 Energy changes during chemical reactions.............................. 49 2.3 Activation energy and the activated complex........................... 50 2.4 Catalysts...................................................................................... 50 2.5 Energy changes during chemical reactions: ∆H....................... 50 2.6 Endothermic and exothermic reactions.................................... 51 2.7 Rates of reactions...................................................................... 54 2.8 Factors which affect reaction rate............................................. 55 © Department of Basic Education 2015 CONTENTS v Mind the Gap Chemistry © Department of Basic Education 2015 2.9 The Collision Theory................................................................... 55 2.10 The mechanism of reactions..................................................... 56 2.11 Measuring rates of reactions..................................................... 59 Unit 3: Chemical equilibrium....................................................78 3.1 Summary..................................................................................... 78 3.2 Key concepts............................................................................... 78 3.3 Factors that influence chemical equilibrium position.............. 82 3.4 Le Châtelier’s Principle.............................................................. 82 3.5 The Equilibrium Constant (Kc) (The Law of Mass Action)......... 90 3.6 Interpretation of graphs for chemical systems in dynamic equilibrium................................................................................103 3.7 Applications of equilibrium principles in the chemical industry..................................................................................... 117 Unit 4: Acids and bases...........................................................122 4.1 Summary...................................................................................122 4.2 Properties of acids and bases................................................. 124 4.3 Common acids..........................................................................125 4.4 Common bases.........................................................................126 4.5 Mono- and polyprotic acids...................................................... 127 4.6 Conjugate acid-base pairs....................................................... 127 4.7 Ampholyte (amphiprotic) substance........................................ 131 4.8 Salt hydrolysis...........................................................................132 4.9 Acid-base indicators.................................................................134 4.10 Acid-base titrations (volumetric analysis)............................... 137 4.11 Preparing a standard solution................................................. 137 4.12 Dilution of solutions.................................................................139 4.13 Acid-base titration calculations...............................................140 4.14 The Equilibrium Constant (Kc) (The Law of Mass Action).......144 4.15 Ka and Kb values.......................................................................145 4.16 The relationship between Ka and Kb for a substance............146 4.17 Auto-ionisation of water........................................................... 147 4.18 Equilibrium constant for water (Kw)......................................... 147 4.19 The pH scale............................................................................. 147 4.20 pH Calculations for strong acids and bases...........................149 4.21 Summary: Strong and weak acids and bases........................150 4.22 Summary: Concentrated and dilute acids and bases............ 151 Unit 5: Electrochemistry..........................................................155 5.1 Summary...................................................................................155 5.2 Key concepts: Definitions and terminology.............................155 5.3 Electrochemical cells................................................................ 157 5.4 Electrolytic cells........................................................................159 5.5 Application of electrolysis........................................................ 161 5.6 Voltaic (Galvanic) cells.............................................................169 5.7 Cell notation.............................................................................. 171 5.8 Standard electrode potentials................................................. 173 5.9 The standard hydrogen electrode............................................ 178 5.10 The emf of an electrochemical cell.........................................180 vi CONTENTS  © Department of Basic Education 2015  Mind the Gap Chemistry  © Department of Basic Education 2015 Unit 6: The chlor-alkali industry..............................................193 6.1 Summary...................................................................................193 6.2 Definitions and terminology.....................................................194 6.3 The chlor-alkali industry – reactants and products................195 6.4 The chlor-alkali industry – industrial process.........................196 Unit 7: The fertiliser industry...................................................202 7.1 Nutrients required by plants....................................................202 7.2 Functions and sources of the primary mineral nutrients.......203 7.3 The industrial production of fertilisers....................................206 7.4 Flowchart: The industrial production of fertilisers.................. 207 7.5 N:P:K fertilisers......................................................................... 210 7.6 Excessive use of fertiliser and the environment.................... 213 7.7 Alternatives to inorganic fertilisers.......................................... 215 © Department of Basic Education 2015 CONTENTS vii Mind the Gap Chemistry  © Department of Basic Education 2015 We are confident that this Dear Grade 12 learner Mind the Gap study This Mind the Gap study guide helps you to prepare for the end-of-year guide can help you to prepare well so that you CAPS Grade 12 exam. pass the end-of-year The study guide does NOT cover the entire curriculum, but it does focus on exams. core content of each knowledge area and points out where you can earn easy marks. You must work your way through this study guide to improve your understanding, identify your areas of weakness and correct your own mistakes. To ensure a good pass, you should also cover the remaining sections of the curriculum using other textbooks and your class notes. Overview of the Grade 12 exam The following topics make up each of the TWO exam papers that you write at the end of the year: Cognitive level Description Paper 2 (Chemistry) 1 Remembering/Recall 15% 2 Understanding/Comprehension 40% 3 Applying and analysing 35% 4 Evaluating and creating (synthesis) 10% Paper Type of questions Duration Total Date Marking Chemistry 10 multiple-choice 2 questions – 20 marks 3 hours 150 October/November External Structured questions – 130 marks Paper 2: Chemistry Focus Content Marks Total Duration Weighting of cognitive levels Chemical change 84 150 3 hours 15 40 35 10 marks viii introduction  © Department of Basic Education 2015  Mind the Gap Chemistry  © Department of Basic Education 2015 How to use this study guide Look out for these icons in the This study guide covers selected parts of the different topics of the CAPS study guide. Grade 12 curriculum in the order they are usually taught during the year. The selected parts of each topic are presented in the following way: An explanation of terms and concepts; NB PAY SPECIAL ATTENTION NB Worked examples to explain and demonstrate; PAY SPECIAL ATTENTION NB NB Activities with questions for you to answer; and Answers for you to use to check your own work.PAY SPECIAL ATTENTION NB NB HINT! HINT! hint hint Hints to help you remember a concept NB PAY SPECIAL ATTENTION Pay special attention NBhint HINT! orEGguide you in e.g. EG - worked examples Worked examples e.g. - worked examples solving problems exams HINT! Step-by-step e.g. exams EG - worked examples Refers you to the Activities with hint questions for you instructions exemplar paper to answer exams e.g. EG - worked examples activity The activities are based on exam-type questions. activity Cover the answers Use this study ACTIVITIES boy provided and do each activity on your own. Then check your answers. and girl-left and ACTIVITIES boy guide as a workbook.right of page exams Make notes, draw pictures, and girl-left and Reward yourself for things you get right. If you get any incorrect right of page activity answers, make sure you understand where activity you went wrong before and highlight important activity concepts. moving on to the next section. ACTIVITIES boy and girl-left and right of page In these introduction pages, we will go through the mathematics that youactivity need to know, in particular, algebra activity and graphs. These are Step by step comment comment comment crucial skills that you willACTIVITIES need boy for any subject that makes use of Step by step comment mathematics. Make surerightyou of page understand these pages before you go and girl-left and any further. activity Step by step comment comment Go to www.education.gov.za to download past exam papers for you to practice. Step by step comment comment © Department of Basic Education 2015 INTRODUCTION ix Mind the Gap Chemistry © Department of Basic Education 2015 Top 10 study tips 1. Have all your materials ready before you begin studying – pencils, pens, highlighters, paper, etc. Try these study tips to make learning easier. 2. Be positive. Make sure your brain holds on to the information you are learning by reminding yourself how important it is to remember the work and get the marks. 3. Take a walk outside. A change of scenery will stimulate your learning. You’ll be surprised at how much more you take in after being outside in the fresh air. 4. Break up your learning sections into manageable parts. Trying to learn too much at one time will only result in a tired, unfocused and anxious brain. 5. Keep your study sessions short but effective and reward yourself with short, constructive breaks. 6. Teach your concepts to anyone who will listen. It might feel strange at first, but it is definitely worth reading your revision notes aloud. 7. Your brain learns well with colours and pictures. Try to use them whenever you can. 8. Be confident with the learning areas you know well and focus your brain energy on the sections that you find more difficult to take in. 9. Repetition is the key to retaining information you have to learn. Keep going – don’t give up! 10. Sleeping at least 8 hours every night, eating properly and drinking plenty of water are all important things you need to do for your brain. Studying for exams is like strenuous exercise, so you must be physically prepared. If you can’t explain it simply, you don’t understand it well enough. Albert Einstein x introduction  © Department of Basic Education 2015  Mind the Gap Chemistry  © Department of Basic Education 2015 Mnemonics A mnemonic code is a useful technique for learning information that is difficult to remember. Here’s the most useful mnemonic for Mathematics, Mathematical Literacy, and Physical Science: BODMAS: B – Brackets O – Of or Orders: powers, roots, etc. D – Division Mnemonics encode information and make it easier to remember M – Multiplication A – Addition S – Subtraction Throughout the book you will be given other mnemonics to help you remember information. The more creative you are and the more you link your ‘codes’ to familiar things, the more helpful your mnemonics will be. Education helps one cease being intimidated by strange situations. Maya Angelou © Department of Basic Education 2015 INTRODUCTION xi Mind the Gap Chemistry © Department of Basic Education 2015 Mind maps There are several mind maps included in the Mind the Gaps guides, summarising some of the sections. Mind maps work because they show information that we have to learn in the same way that our brains ‘see’ information. As you study the mind maps in the guide, add pictures to each of the branches to help you remember the content. You can make your own mind maps as you finish each section. How to make your own mind maps: 1. Turn your paper sideways so your brain has space to spread out in all directions. 2. Decide on a name for your mind map that summarises the information you are going to put on it. Mind mapping 3. Write the name in the middle and draw a circle, bubble or picture your notes makes around it. them more interesting 4. Write only key words on your branches, not whole sentences. and easier to remember. Keep it short and simple. 5. Each branch should show a different idea. Use a different colour for each idea. Connect the information that belongs together. This will help build your understanding of the learning areas. 6. Have fun adding pictures wherever you can. It does not matter if you can’t draw well. xii introduction  © Department of Basic Education 2015  Mind the Gap Chemistry  © Department of Basic Education 2015 On the day of the exam 1. Make sure you have all the necessary stationery for your exam, i.e. pens, pencils, eraser, protractor, compass, calculator (with new batteries). Make sure you bring your ID document and examination admission letter. 2. Arrive on time, at least one hour before the start of the exam. 3. Go to the toilet before entering the exam room. You don’t want to waste valuable time going to the toilet during the exam. 4. Use the 10 minutes reading time to read the instructions carefully. This helps to ‘open’ the information in your brain. Start with the question you think is the easiest to get the flow going. 5. Break the questions down to make sure you understand what is being asked. If you don’t answer the question properly you won’t get any marks for it. Look for the key words in the question to know how to answer it. Lists of difficult words (vocabulary) is given a bit later on in this introduction. 6. Try all the questions. Each question has some easy marks in it so make sure that you do all the questions in the exam. 7. Never panic, even if the question seems difficult at first. It will be linked with something you have covered. Find the connection. GOOD LUCK! 8. Manage your time properly. Don’t waste time on questions you are unsure of. Move on and come back if time allows. Do the questions that you know the answers for, first. 9. Write big and bold and clearly. You will get more marks if the marker can read your answer clearly. 10. Check weighting – how many marks have been allocated for your answer? Take note of the ticks in this study guide as examples of marks allocated. Do not give more or less information than is required. © Department of Basic Education 2015 INTRODUCTION xiii Mind the Gap Chemistry  © Department of Basic Education 2015 Question words to help you answer questions It is important to look for the question words (the words that tell you what to do) to correctly understand what the examiner is asking. Use the words in the table below as a guide when answering questions. Question word What is required of you Analyse Separate, examine and interpret Calculate This means a numerical answer is required – in general, you should show your working, especially where two or more steps are involved Classify Group things based on common characteristics Compare Point out or show both similarities and differences between things, concepts or phenomena Define Give a clear meaning Describe State in words (using diagrams where appropriate) the main points of a structure/process/phenomenon/ investigation Determine To calculate something, or to discover the answer by examining evidence Differentiate Use differences to qualify categories Discuss Consider all information and reach a conclusion Explain Make clear; interpret and spell out Identify Name the essential characteristics PAY SPECIAL ATTENTION In every exam Label Identify on a diagram or drawing question, put a CIRCLE around the question word and List Write a list of items, with no additional detail underline any other important Mention Refer to relevant points key words. These words tell you exactly what is Name Give the name (proper noun) of something being asked. State Write down information without discussion Suggest Offer an explanation or a solution Tabulate Draw a table and indicate the answers as direct pairs xiv introduction  © Department of Basic Education 2015  Mind the Gap Chemistry  © Department of Basic Education 2015 Vocabulary approximate (v. & adj.). Come close to (v); roughly, almost, not perfectly accurate, close but not exact. The The following vocabulary consists of all the verb is pronounced “approxi-mayt” difficult words used in Mind the Gap Mathematics, and the adjective is pronounced Mathematical Literacy, and Physical Science. We “approxi-mitt”. suggest that you read over the list below a few aquatic (adj). Growing or living near or in times and make sure that you understand each water. term. Tick next to each term once you understand arbitrary (adj). Based on random choice; it so you can see easily where the gaps are in your unrestrained and autocratic. knowledge. KEY C Abbreviation Meaning (v) verb: doing-word or action word, category (n). Class or group of things. such as “walk” cause (v). Make something happen. (n) noun: naming word, such as cause (n). The person or thing that “person” makes something happen; an aim (adj) adjective: describing word such as or movement to which a person is “big” committed. (adv) adverb: describing word for verbs, causality (n). Someone or something such as “fast” responsible for a result. (prep) preposition: a word describing a collide (v). To crash into; to hit. position, such as “on”, “at” complex (adj). Consisting of many different (sing) singular: one of parts; not easy to understand (n) a group or system of things (pl) plural: more than one of connected in a complicated way. (abbr) abbreviation component (n). A part. General terms compose (v). To make up from parts. composite (n). Something made up of parts; (adj) made up of several parts. Term Meaning condition (n). The state something is in; the A situation that must exist before something else is possible. abbreviate (v). Make shorter. conjunction (n). When two or more things abundant (adj). Having plenty of something. come together at the same point; accept (v). Agree to receive something; in grammar, a part of speech say yes to; believe; tolerate that connects words, sentences, something. phrases or clauses, e.g.: “and” account for (v). Explain why. consider (v). Think about. adjacent (adj). Next to something. contrast (v). Show the difference between; (n). something that is very affect (v). Make a difference to; touch different from what it is being the feelings of. Do not confuse compared with. with effect. See effect. conversely (adv). The opposite of. analyse (v). Examine something in detail. counteract (v). Act against something in order ante- (prep). Before (e.g., ante-natal – to stop it. before birth) D anti- (prep). Against (e.g., anti- apartheid – against apartheid). apparent (adj). Clearly visible; the way data (pl), (n). Information given or found. something seems to be or the way datum (sing) it appears. deduce (v). To work something out by appear (v). Come into sight; seem to be. reasoning. © Department of Basic Education 2015 INTRODUCTION xv Mind the Gap Chemistry © Department of Basic Education 2015 deduction (n). Conclusion or idea that find (v). Discover or locate. someone has worked out. find (n). Results of a search or define (v). Give the meaning of a word or discovery. words. finding (n). Information discovered as the definition (n). The meaning of a word or result of an inquiry. words. fixed (adj). Not able to move, attached; deliver (v). To bring and hand over. or repaired, not broken. denote (v). To refer to or mean something. format (n). Layout or pattern; the way determine (v). Work out, usually by something is laid out. experiment or calculation. discreet (adj). Careful, polite. G discrete (adj). Single, separate, distinct, a part. global (adj). Found all over the world (globe). E H effect (n). Result. effect (v). Carry out, do, enact. hazard (n). Something dangerous. eject (v). Force or throw something heterogeneous (adj). Made up of many different or someone out violently or parts. suddenly. homogeneous (adj). Uniform, made up of the elapse (v). Pass by or finish, e.g., time. same types of parts. establish (v). Show or prove, set up or hypothesis (n). A theory or proposed create. explanation. exceed (v). Go beyond. hypothetical (adj). Theoretical or tentative; excess (n). More than necessary. waiting for further evidence. excluding (prep). Not including. exclusive (adj). Excluding or not admitting I other things; reserved for one particular group or person. identify (v). Recognise or point out. exemplar (n). A good or typical example. illustrate (v). Give an example to show what exempt (v). To free from a duty. is meant; draw. exempt (adj). Be freed from a duty. impair (v). Weaken or damage. exemption (n). Being freed from an imply (v). Suggest without directly saying obligation. what is meant. exhibit (v). To show or display. indicate (v). Point out or show. exhibit (n). A part of an exhibition. initial (n). First. expel (v). Force someone or something initiation (n). The action of beginning to leave a place. Eject. something; the action of admitting extent (n). The area covered by somebody into a group or something. organisation. insufficient (adj). Not enough. F interchange- (adj). Can be swapped or able exchanged for each other. investigate (v). Carry out research or a study. factor (n). A circumstance, fact or influence that contributes to a issues (v). Comes out of. result; a component or part. issues (n). An important problem or a factory (n). A place where goods are topic for debate. made or put together from parts. xvi introduction  © Department of Basic Education 2015  Mind the Gap Chemistry  © Department of Basic Education 2015 M Q macroscopic (adj). Visible without being made quality (n). The standard of something bigger. compared to other similar things; manipulate (v). Handle or control (a thing or a a characteristic of someone or person). something. microscopic (adj). Very small, not visible R without being made bigger. motivate (v). Give someone a reason for reciprocal (adj). Given or done in return. doing something. record (v). Make a note of something multiple (adj). Many. in order to refer to it later (pronounced ree-cord). N record (n). A note made in order to refer to it later; evidence of something; a copy of something (pronounced negligible (adj). Small and insignificant; rec-cord. can be ignored. From “neglect” relative (adj). Considered in relation to (ignore). something else; compared to. numerical (adj). Relating to or expressed as relative (n). A family member. a number or numbers. represent (v). Be appointed to act or speak numerous (adj). Many. for someone; amount to. resolve (v). Finalise something or make O it clear; bring something to a conclusion. observe (v). Look at; watch carefully. respect (v). Admire something or someone; consider the obtain (v). Get. needs or feelings of another occur (v). Happen. person. operate (v). Work; drive; control. respectively (adj). In regards to each other, optimal (adj). Best; most favourable. in relation to items listed in the optimum (adj). Best; (n) the most same order. favourable situation for growth or success. S overabundance (n). More than enough; too much. simultaneously (adv). At the same time. P site (n). Place. suffice (v). Be enough. phenomenon (n). A fact or situation that is seen surplus (adj). More than is needed. to exist or happen. survey (n). A general view, examination, phenomena (n). Plural of phenomenon. or description of someone or prefix (n). Part of a word that is attached something. to the beginning of many different survey (v). Look closely at or examine; words, changing their meaning, consider a wide range of opinions e.g., prehistoric – before written or options. records were kept. prepare (v). Make ready before an event; T set things up. principal (n). Head of a school. tendency (n). An inclination to do something principal (adj). Main or most important. in a particular way; a habit. principle (n). A basic truth that guides the tertiary (adj). Third level. way a person behaves. provide (v). Make available for use; supply. © Department of Basic Education 2015 INTRODUCTION xvii Mind the Gap Chemistry © Department of Basic Education 2015 U affinity (n). A liking for something; an attraction to something; a tendency to react with something uniform (n). Standardised clothing. (chemistry). See also paraffin. uniform (adj). Remaining all the same at alcohol (n). In common usage, ethanol all times; unchanging. C2H5OH. Technically, any organic substance or molecule containing V an -OH group. See organic. aldehyde (n). Any organic molecule containing -CHO, formed by oxidising alcohols. verify (v). Show to be true; check for See alcohol and organic. truth; confirm. algae (n). Adjective: algal (pertaining to vice versa (adv). The other way round. algae); an aquatic plant (lives in versus (prep). Against. Abbreviated “vs” water), which lacks leaves, stems, and sometimes “v”. roots. algebra (n). A mathematical system Technical terms where unknown quantities are represented by letters, which A can be used to perform complex calculations through certain rules. alkali (n). See base. absorption (n). To take into; the process of taking something in. alkane (n). An organic molecule or compound or substance which account (n. & v.). Finance: A record of contains only single bonds income and expenditure. To between carbons. See organic. explain (v), e.g. “Account for why the sky is blue”. alkene (n). An unsaturated organic molecule, compound or substance, acetic (adj). Pertaining to vinegar; an which contains at least one double organic molecule containing two bond between carbons. See carbons. See organic, eth- for organic and unsaturated. more. alkyl (n). A prefix (word part) which shows acetone (n). Propanone. CH3COCH3; the that the word after it has an alkane ketone of acetic acid. See ketone group attached to it, by removing for more. one hydrogen from the alkane. acetylene (n). Ethyne, C2H2. Used in welding alkyne (n). An unsaturated organic torches (blowtorches). See also molecule, compound or substance, alkene. which contains at least one triple acid (n). A proton donor or substance bond between carbons. See that ionises into H+ or H3O+ when organic and unsaturated. dissolved in water; sour-tasting amalgam (n). General use: a mixture. In substance; corrosive; pH below 7. chemistry, specifically a mercury See also base and alkali. alloy. acidified (adj). To have been made acidic. amide (n). An organic compound acidity (n). How acid something is. containing the group -C(O)NH2; an activated (adj). Made to function. Chemistry: inorganic compound containing something moved into an unstable the group NH2–. higher-energy level or state. amine (n). The same as an amide except Usually “activated complex”, the the -NH2 can be attached to combination of reactants just anything, and does not have the before they turn into products. See CO group shown above. also reactant, reagent, product. ammonia (n). NH3. activation (n). The process of activating ammonium (adj). NH4+, found as a cation or as something. “Activation energy”, part of a salt. See salt and cation. the required energy to create an activated complex. amphiprotic (n). See ampholyte. aerosol (n). A solution of substances in air or ampholyte (n). A substance that can act as an other gas, e.g. as in an aerosol can. acid or base. See acid, base. xviii introduction  © Department of Basic Education 2015  Mind the Gap Chemistry  © Department of Basic Education 2015 anions (n). A negative ion. See cation, ion. axis (sing), (n). A line along which points can be anode (n). The negative electrode of axes (pl, plotted (placed), showing how far a cell or current supplier; the pronounced they are from a central point, called positive electrode of an electrolytic “akseez”) the origin. See origin. “Vertical axis” system; attracts negative ions. See or “y-axis” refers to how high up a electrode, cathode. point is above the origin (or how far below). “Horizontal axis” or “x-axis” antacid (n). A substance used to neutralise refers to how far left or right a point (react with) acid. E.g. chalk. See is away from the origin. acid, neutralise. apparatus (n). Equipment; parts of a scientific experiment. B aqueous (n). Dissolved in water. Arrhenius (n). Arrhenius’ theory of acids and bakelite (n). A type of hard, brittle plastic bases: That acids produce H+ or that can’t melt once it has set H3O+ in water, and bases produce or taken shape (thermosetting), OH–. See Brønsted-Lowry. made from phenol C6H5OH, and formaldehyde (methanal), CH2O. asbestos (n). A fireproof fibrous substance containing silicon used for balance (v. & n.). To make two things equal fireproofing. (v); a scale to weigh objects (n). Chemistry: to compare two sides asbestosis (n). A lung disease caused by of a chemical equation and make inhaling asbestos fibres, can lead sure that there are the same to cancer. numbers of atoms on both sides. atm (n). Abbreviation: atmospheres base (n). A proton acceptor, or substance of pressure (1 atm = 101,3 kPa). that ionises into OH– when The pressure of the air at sea dissolved in water; a bitter-tasting level. Same as “bar” (barometric substance, corrosive, pH above 7. pressure). See also acid. Do not confuse with ATM (n). Abbreviation: automatic teller common everyday use, meaning machine. “the bottom” or “low”. atmosphere (n). The air or the gases basic (n). Bitter or made of a base. Do not surrounding a planet; the sky; as a confuse with popular use, meaning unit of measurement, see atm. “low” or “simple” or “crude”. atmospheric (adj). To do with the atmosphere. battery (n). A collection of cells connected atom (n). The smallest unit of a chemical in series (end-to-end). See cell. In element, which, if broken down common use, “battery” is used to further, no longer behaves in the mean the same as “cell” (e.g. a same way chemically. Consists of penlight or AA cell), but this use is a nucleus or centre part which is incorrect except for a car battery, positively charged, and an electron which consists of a series of cells. cloud (negatively charged) which benzoic (adj). Contains benzene or a surrounds the nucleus. See nuclear. benzene ring. attract (v). To bring something closer. bi- (prefix). Two. average (n). Mathematics: The sum of parts bicarbonate (n). Any salt containing the ion divided by the quantity of parts. In -HCO3–. So called because the common use: neither very good, carbonate (CO32–) attaches to strong, etc., but also neither very another ion and the hydrogen weak, bad, etc; the middle. In (two bonds). The name “hydrogen Physical Science and Mathematics: carbonate” is now preferred. if you are asked to find the average, biodegradable (adj). Can be broken down by you always have to calculate it natural processes e.g. involving using the information you have. For bacteria, moulds, fungus, etc. example, the average of (1;2;3) is 2, because (1+2+3)/3 = 2. See also biodiesel (n). Diesel (a type of petrol) made mean, median and mode. from plants rather than fossil fuels (coal, oil). avogadro (n). 6,023 × 1023 particles; one (constant or mole. See mole and mol. number) © Department of Basic Education 2015 INTRODUCTION xix Mind the Gap Chemistry © Department of Basic Education 2015 BODMAS (abbr). Brackets, of/orders carbohydrate (n). Organic compounds containing (powers, squares, etc), division, carbon and hydrogen, occurring multiplication, addition, subtraction. in foods and living tissues and A mnemonic (reminder) of the including sugars, starch, and correct order in which to do cellulose. They contain hydrogen mathematical operations. and oxygen in the same ratio boil (v). Physics: to cause a liquid’s as water (2:1). Not the same vapour pressure to exceed as hydrocarbons, which are any the pressure of the gas in the substances containing mostly container, usually by heating it, hydrogen and carbon. but it can be done by lowering carbonate (n). -CO32– the pressure of the gas in the carbonic (adj). Anything containing carbon, container, too. See vapour or more specifically, CO2 pressure. In common usage, to make a liquid hot until it bubbles. carbonyl (adj). Containing double bonded bond (n). A connection. In physics and carbon and oxygen: =C=O. chemistry, between atoms and carboxyl (adj). Containing -COOH. molecules. carboxylic (adj). Carboxyl-containing. breadth (n). How wide something is. From Cartesian (adj). Anything believed or the word “broad”. proposed by Rene Descartes. brine (n). A saturated salt solution (a In particular, the x-and-y axis mixture of water and salt which coordinate system. can’t dissolve any more salt). catalyst (n). A substance that alters the bromide (n). Something containing bromine, rate of a chemical reaction without usually one ion. See ion. itself being consumed in the bromo- (prefix). Something containing reaction. Without qualification, or bromine. as “positive catalyst”, something bromothymol (n). A type of acid-base indicator that starts or speeds up a reaction. (blue) used to tell whether something A “negative” catalyst slows down a is an acid or base. Turns blue (in reaction. base) or yellow (in acid). catalytic (n). Containing or using a catalyst. Brønsted-Lowry (n). A theory of acids and bases cathode (n). The positive electrode of a cell which says that acids are proton or current supplier; the negative donors (they give away protons), electrode of an electrolytic and bases are proton acceptors system; attracts positive ions. See (they take protons). Since H+ is electrode, anode, ion. just a proton, this does not mean something different from the cathodic (adj). Involving a cathode. Cathodic Arrhenius theory that an acid is a protection: To use a more reactive substance that dissolves into H+ in metal to protect a less reactive water. See proton, Arrhenius. metal from oxidation. See anode, but- (prefix). Four carbons. Pronounced cathode, oxidise. “beaut”. E.g. butane is a four- cation (n). A positively charged ion. See carbon alkane. anion, ion. caustic (adj). Basic; a base. C cell (n). An apparatus that generates electricity using electrochemistry. calibrate (v). To adjust a measuring tool An AA or Penlight battery, as it is or measurement against a commonly called, is a cell. A car known accurate measurement to battery consists of a number of ensure that the measuring tool or cells inside a single container. measurement is accurate; to check CFC (n). A chlorofluorocarbon. A a measurement or measuring substance containing carbon, tool’s accuracy; to mark with chlorine and fluorine. Responsible accurate measurements using a for breaking down ozone (O3) which standard scale like cm, mm, mℓ, protects us from too much UV etc. Common use: to assess or radiation from the sun. evaluate carefully. xx introduction  © Department of Basic Education 2015  Mind the Gap Chemistry  © Department of Basic Education 2015 chain (n). Chemistry: a long series of compound (n). A substance made up of atoms bonded together, usually molecules consisting of more carbon. than one different type of atom, charge (n). Chemistry: having too chemically bonded in a constant many or too few electrons ratio. E.g. Water (H2O) is a (most commonly), resulting in compound, but Sulphur powder a substance ionising. A positive (S) is not. In a compound, the charge results from too few original chemicals (reactants) have electrons, and a negative charge reacted or merged to form a new from too many electrons. Physics: substance. Compare to mixture. a basic feature of all physical compressed (adj). Subjected to pressure, electromagnetic particles, except, squashed. e.g. neutrons and photons, which concentration (n). The number of moles of have zero charge. All protons have substance per unit volume. a positive charge, all electrons See mol, moles. How “strong” a have a negative charge. solution is. See solution. chart (v). To draw a diagram comparing condensation (n). When a vapour or gas cools values on Cartesian axes. down and starts to collect into Le Châtelier’s (n). That in reversible reactions, larger droplets; changing phase Principle chemical systems will favour the from vapour or gas to liquid. forward or reverse reaction to Condensation reaction: to produce minimise the change imposed a larger molecule from two smaller on the system. If a chemical ones. equilibrium is disturbed by conditions (n). Physics and Chemistry: how changing the conditions, the (STP) the environment is: temperature position of equilibrium moves to and pressure. STP (Standard counteract the change. Temperature and Pressure is 25°C chloro- (prefix). Containing chlorine. and 1 atm). chlorofluoro- See CFC. conjugate (n). To join together. Chemistry: two carbons things that belong together, e.g. chloroform (n). CHCℓ2. A liquid formerly used conjugate acid-base pairs. as an anaesthetic. conservation (n). A law which describes chlorophyll (n). A green substance found something that does not change. in plants which enables E.g. the conservation of matter- photosynthesis (broadly, energy says that matter-energy generating food from CO2). See cannot be created or destroyed, photosynthesis. only transformed from one form into another. There are a number coefficient (n). A constant value placed of other conservations, e.g. next to an algebraic symbol as a momentum and torque. multiplier. Same as constant (see below). Or: a multiplier or factor constant (n). See coefficient. Means that measures a property, e.g. “unchanging”. coefficient of friction. contaminate (v). Chemistry: to introduce combustion (n). The process of burning, usually impurities or other substances in oxygen. Rapid oxidation. which are not meant to be part of a reaction. completion (n). Chemistry: when a reaction no longer proceeds (continues) control (n. and v.). To ensure something because it has run out of one does not change without or more of the reactants. See being allowed to do so (v); reactant, reaction. an experimental situation to which nothing is done, in order complex (n). See activated. to compare to a separate (activated) experimental situation, called the ‘experiment’, in which a change is attempted. The control is then compared to the experiment to see if a change happened. © Department of Basic Education 2015 INTRODUCTION xxi Mind the Gap Chemistry © Department of Basic Education 2015 control variable (n). A variable that is held constant degradable (adj). Capable of breaking down or in order to discover the relationship being broken down. between two other variables. dehydrating (adj). To remove water from. A “Control variable” must not be (agent) “dehydrating agent” is a substance confused with “controlled variable” which can remove water from (see independent variable). another substance. E.g. H2SO4, coordinate (n). The x or y location of a point on ethanol. a Cartesian graph, given as an x or dehydration (n). The process of removing water y value. Coordinates (pl) are given from a substance. as an ordered pair (x, y). dehydrogena- (n). The process of removing correlate (v). To see or observe a tion hydrogen from a substance. relationship between two things, without showing that one causes dehydrohalo- (n). To remove hydrogen and a the other. genation halogen from a substance. See halogen. correlation (n). That there is a relationship between two things, without denominator (n). See divisor. In popular speech: showing that one causes the other. a common factor. correspond (v). To pair things off in a depend (v). To be controlled or determined correlational relationship. For two by something; to require something things to agree or match. E.g. A to happen or exist first. corresponds to 1, B corresponds to dependent (adj/n). A variable whose value 2, C corresponds to 3, etc. (variable) depends on another; the thing corrode (v). Chemistry: to destroy by that comes out of an experiment, gradual chemical action. Usually the effect; the results. See also refers to acidic action. Compare independent variable and control to erode. General use: to destroy variable. The dependent variable gradually. has values that depend on the independent variable, and we plot corroding (adj). A process or substance it on the vertical axis. that corrodes; to be subject to corrosion. depleted (adj). Having been used up; run out of. corrosion (n). To corrode. deposit (n). Finance: to place money into corrosive (adj). To be capable of corroding an account. Physical Science: to something. cover a surface of one substance counteract (v). Oppose or resist. with another substance, e.g. metal covalent (adj). Chemistry: a bond which plating on an electrode. results from sharing electrons determine(s) (v). To cause; to ensure that; to set between atoms. Compare ionic (causation) up so that; to find out the cause of. bond. di- (prefix). Two. cracking (n). A process of breaking a diamine (n). A substance containing two complex organic molecule into amine groups. See amine. simpler parts using heat and pressure. diammonium (n). Having two ammonium (NH4) groups. See ammonium. cubed (adj). The power of three; diaphragm (n). A thin sheet of any substance multiplied by itself three times. covering a gap. Biology: the muscle cubic (adj). Shaped like a cube; having below the lungs which moves to been multiplied by itself three cause breathing. Electrochemistry: times. a thin sheet inside a cell which current (n). Flowing electrons. separates the electrodes. It is porous and allows solutions containing ions through, but serves D to separate gas products. difference (n). Mathematics: subtraction. decompose (v). To break down into Informally: a dissimilarity. How components. things are not the same. xxii introduction  © Department of Basic Education 2015  Mind the Gap Chemistry  © Department of Basic Education 2015 dilute (adj. & v). To lower the domain (n). The possible range of x-values concentration of a solution. See for a graph of a function. See solution and concentration (v): range. a solution which has had its durable (adj). Tough; something that can concentration lowered (adj). endure. dilution (n). The opposite of concentration; dynamic (adj). Changing often. Relating how low a concentration is, to forces that produce motion. measured in mol/dm3; the process Opposite of static. See static and of diluting. electrostatic. dimer (n). A molecule made of two identical parts. See also polymer. E diode (n). A semiconductor device with two terminals (electrodes), usually allowing current to flow in one ecosystem (n). An integrated, complex, direction only. interacting, mutually dependent diol (n). A molecule with two alcohol/ living system or environment. hydroxyl (OH) groups. electric (adj). Containing electricity dipole (n). A polarised molecule with a (electrons). distinctly positive and distinctly electro- (adj). Where chemical reactions negatively-charged end. chemical cause the release of electrons, diprotic (n). Having two protons. usually into a circuit. General use: anything relating to electrical and displace (v). To move or relocate something. chemical phenomena. dissipate (v). To disperse or scatter (e.g. electrode (n). General use: the point where gas). Thermodynamics (Energy): electrons enter or exit a power to cause energy to be lost as heat. source or a circuit. Specifically Popular use: to disappear. (Electrochemistry): Part of a circuit dissociate (v). To break apart; to no longer be dipped into a solution to receive or associated with. release electrons. See anode and dissolve (v). To break up into ions within a cathode. solution (usually water); to mix a electrolysis (n). The splitting of a chemical solid (usually powder) into a liquid, into ions. (The chemical is usually to form a solution. See solution, dissolved in water or another ion. Alternative popular use: to solution.) It is done by means of bring to an end. electricity. See electrochemical. distil(l) (v). To purify through repeated electrolyte (n). A substance (usually liquid heating of a liquid and collection or gel solution) which contains of condensation. The heating a compound that will be split by process causes the liquid to form electricity. Ionisable solutions or gas or vapour, which condenses components. on the side of the heating vessel electromotive (adj). Usually electromotive force (container) or an exit tube, leaving or emf. The potential difference impurities behind in the heating caused by electromagnetism, vessel. which causes current to flow. distribution (n). How something is spread Producing a current with out. Mathematics: the range and electromagnetism. See emf. variety of numbers as shown on a electron (n). A fundamental physical graph. particle bearing a negative charge, disturb (v). Chemistry: to mix or stir a liquid weighing approximately 9 × 10−28g, or solution; to shake it up. which is found around atomic divisor (n). The number below the line nuclei in areas called ‘orbitals’. in a fraction; the number that is Responsible for electricity and dividing the other number above chemical reactions. Symbol e–. See the fraction line. See numerator, proton, nucleus. denominator. © Department of Basic Education 2015 INTRODUCTION xxiii Mind the Gap Chemistry © Department of Basic Education 2015 electroplate (v). To cover a surface of a less energy (n). Work or the ability to do valuable substance with a more work. There are various forms of valuable metal, using electrolysis. energy: motion (Ek), light energy element (n). Mathematics: part of a set (photons), electrical energy, heat, of numbers. Physics: a pure etc. Energy can neither be created substance made only of atoms of nor destroyed, but only converted one type, with the same number from one form to another. See of protons in each nucleus. An conservation. element cannot be broken down enthalpy (n). The total heat content of a further without losing its chemical system, H, including the chemical properties. Each element has a energy. unique atomic number which is the equilibria (pl), (n). The state of being in balance. number of protons in the nucleus. equilibrium Chemistry: when the forward See nucleus, atom, isotope. (sing) reaction rate is equal to the Popular use: part of. reverse reaction rate. See Le eliminate (v). To remove or get rid of. Châtelier’s Principle. Mathematics: to cancel a factor erode (v). To wear away by means of out of one side of an equation by friction (rubbing). dividing by that factor throughout, or by substituting in another ester (n). An organic compound formula or value that is equal. produced by bonding an alcohol Chemistry: to produce a smaller to a carboxylic (organic) acid, sub