INVESTIGATIONSHSC CHEMISTRY

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All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of Science Press. ABN 98 000 073 861

Science Press 2009First published 2009

Science PressPrivate Bag 7023 Marrickville NSW 1475 AustraliaTel: (02) 9516 1122 Fax: (02) 9550 1915sales@sciencepress.com.au www.sciencepress.com.au

Thanks to Oatley campus of Georges River College for the use of equipment to photograph.

iiiDot Point HSC Chemistry Investigations Contents

Science Press

Introduction v

Verbs to Watch vi

Dot Points

Production of Materials vii

The Acidic Environment ix

Chemical Monitoring and Management xi

Industrial Chemistry xiii

Shipwrecks, Corrosion and Conservation xv

Investigations

Production of Materials 1

The Acidic Environment 63

Chemical Monitoring and Management 137

Industrial Chemistry 197

Shipwrecks, Corrosion and Conservation 261

Appendix

Answers 312

Data Sheet 318

Periodic Table 319

Contents

iv Dot Point HSC Chemistry InvestigationsContents

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vDot Point HSC Chemistry Investigations

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Introduction

This book contains all the instructions and other information needed for you to carry out the mandatory rst-hand investigations listed in column 3 of the Board of Studies Chemistry syllabus. In some cases more than one experiment has been suggested.

The syllabus requires 35 hours of practical work, but this need not all be experimental work. First-hand investigations include research to gather, process and analyse information, the presentation of information in written or spoken format and the solving of problems. In completing the activities in this book, you will have satised these aspects of the practical work required by the syllabus as detailed in column 3 of the syllabus document.

Note that answers to practical and research exercises have not been provided as this would void the experimentation and research that you need to do in order to get these answers.

Additional extension questions have been provided, where applicable, to encourage higher-order thinking and enable deeper understanding of chemistry concepts. Further examples of questions relevant to rst-hand investigations in column 3 of the syllabus are included in two other books in this series, Dot Point HSC Chemistry and Dot Point HSC Chemistry Multiple Choice.

The dot point numbers allocated to each experiment reect the numbers allocated to that dot point in the other books in this series. Remember that these numbers are author derived and do not appear in the syllabus.

Wherever possible, allowance has been made for variations in experimental method. This is necessary because schools have access to different resources and teachers often wish to design their own activities specic to their resources. Also, you are expected to develop skills in the planning of experiments and if you are always given recipes you will never learn to do this. However, as many students struggle when it comes to planning and writing up experiments and research, many hints are provided.

Experimental and research work is an integral part of the study of Chemistry. It is not meant to stand alone. You should always look for the relevance of your experimental and research work to the topic being studied. Thus it is recommended that after you carry out these activities, and your teacher has checked your work, the completed sheets should be inserted in the appropriate place in your notes.

This book is NOT a series of chemical recipes or a how to do it manual.

It is designed to help you record and evaluate experimental procedures that you will design and carry out during the Chemistry course and to encourage you to see the signicance of information obtained from practical activities and research.

Before you carry out any experimental procedure it is essential that you consult Safety Data Sheets and information from your teacher and textbooks in order to nd out the risks associated with using any chemicals involved and precautions needed to deal with these risks.

Before commencing any practical work, you must discuss with your teacher the necessary precautions for dealing with the chemicals and equipment to be used. All aspects of your experimental design must be approved by your teacher.

Introduction

vi Dot Point HSC Chemistry Investigations

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Verbs to Watch

account/account for State reasons for, report on, give an account of, narrate a series of events or transactions.

analyse Identify components and the relationships among them, draw out and relate implications.

apply Use, utilise, employ in a particular situation.

appreciate Make a judgement about the value of something.

assess Make a judgement of value, quality, outcomes, results or size.

calculate Determine from given facts, gures or information.

clarify Make clear or plain.

classify Arrange into classes, groups or categories.

compare Show how things are similar and different.

construct Make, build, put together items or arguments.

contrast Show how things are different or opposite.

critically (analyse/evaluate) Add a degree or level of accuracy, depth, knowledge and understanding, logic, questioning, reection and quality to an analysis or evaluation.

deduce Draw conclusions.

dene State the meaning of and identify essential qualities.

demonstrate Show by example.

describe Provide characteristics and features.

discuss Identify issues and provide points for and against.

distinguish Recognise or note/indicate as being distinct or different from, note difference between things.

evaluate Make a judgement based on criteria.

examine Inquire into.

explain Relate cause and effect, make the relationship between things evident, provide why and/or how.

extract Choose relevant and/or appropriate details.

extrapolate Infer from what is known.

identify Recognise and name.

interpret Draw meaning from.

investigate Plan, inquire into and draw conclusions about.

justify Support an argument or conclusion.

outline Sketch in general terms; indicate the main features.

predict Suggest what may happen based on available data.

propose Put forward (a point of view, idea, argument, suggestion etc) for consideration or action.

recall Present remembered ideas, facts or experiences.

recommend Provide reasons in favour.

recount Retell a series of events.

summarise Express concisely the relevant details.

synthesise Put together various elements to make a whole.

Verbs to Watch

viiDot Point HSC Chemistry Investigations

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Production of Materials

1. Energy and raw materials from fossil fuels

1.3 First-hand investigation: 3 Alkanes and alkenes with bromine.

1.7 Modelling polymerisation. 9

2. Materials from biomass

2.2 Development and use of a biopolymer. 11

3. Ethanol use and manufacture

3.3 Modelling the dehydration 15 and hydrolysis of ethylene.

3.4 Industrial production of 19 ethanol from sugar cane.

3.8 First-hand investigation: 23 Molar heats of combustion of alkanols.

3.10 Ethanol as a car fuel. 31

3.12 First-hand investigation: 35 Fermentation of glucose.

4. Energy from redox reactions

4.1 First-hand investigation: 41 Galvanic cells.

4.2 First-hand investigation: 45 Potential difference of metals in an electrolyte.

4.9 Calculations using the 49 redox table.

4.10 Chemistry and uses of 53 batteries compared.

5. Nuclear chemistry

5.2 Recent discoveries of elements. 57

5.8 Radioisotopes 59 benets and problems.

Production of Materials

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ixDot Point HSC Chemistry Investigations

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The Acidic Environment

The Acidic Environment

1. Indicators

1.1 First-hand investigation: 65 Natural indicators.

1.2 Indicators colour changes. 71

1.5 Acidic/basicity of 73 household substances.

2. Acidic oxides and the atmosphere

2.7 First-hand investigation: 75 Decarbonation of a soft drink.

2.12 Industrial origins of oxides of sulfur 81 and nitrogen.

3. Acids and pH

3.1 First-hand investigation: 85 Using pH meters or probes

3.4 Naturally occurring acids and bases. 91

3.7 Strong and weak acids. 93

3.8 Ionic equations for acid ionisation. 97

3.9 Modelling acids molecular 99 nature and ionisation.

3.13 Strong and weak acids 101 calculating pH.

3.14 Acids as food additives. 105

4. Acid/base theories

4.1 Using secondary sources. 107

4.6 First-hand investigation: 109 pH of salt solutions.

4.11 First-hand investigation: Titrations. 113

4.12 First-hand investigation: 125 Titration of a domestic substance using computer-based technology.

4.13 Neutralisation in accidents. 129

5. Esterication

5.7 First-hand investigation: 131 Preparation of an ester by reux.

5.9 Esters uses in foods and cosmetics. 135

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x Dot Point HSC Chemistry InvestigationsContents

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xiDot Point HSC Chemistry Investigations

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Chemical Monitoring and Management

Chemical Monitoring and Management

1. The work of chemists

1.1 Researching the work of chemists. 139

2. Monitoring in industry the Haber process

2.9 Development of the Haber 141 process and its signicance.

3. Chemical analysis

3.1 First-hand investigation: 143 Flame tests.

3.2 Monitoring ions in substances we use. 157

3.4 First-hand investigation: 161 Sulfate content of lawn fertiliser.

3.5 Analysing reliability of results. 167

3.7 Interpreting data from AAS analysis. 169

4. Atmospheric chemistry and ozone

4.9 Modelling haloalkanes. 173

4.12 Destruction of atmospheric ozone. 175

4.14 Replacements for CFCs. 177

5. Monitoring the water supply

5.3 First-hand investigation: Water testing. 179

5.4 Monitoring water for heavy metals 187 and eutrophication.

5.5 The local water supply. 193

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xiiiDot Point HSC Chemistry Investigations

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Industrial Chemistry

Industrial Chemistry

1. Resources and replacements

1.1 A natural resource (not a fossil fuel). 199

2. Equilibrium and the equilibrium constant

2.1 First-hand investigation: 201 Modelling an equilibrium reaction.

2.2 First-hand investigation: 207 Analysing an equilibrium reaction.

2.5 Calculating the equilibrium constant (K). 213

3. Sulfuric acid

3.4 Transport and storage of sulfuric acid. 219

3.9 Industrial production of H2SO4 221 chemistry and output.

3.10 First-hand investigation: 225 Reactions of H2SO4.

4. Sodium hydroxide

4.2 First-hand investigation: 229 Electrolysis of sodium chloride.

4.3 Electrolysis of molten and 233 aqueous sodium chloride.

5. Saponication

5.1 First-hand investigation: Saponication. 235

5.2 Saponication. 239

5.5 First-hand investigation: 241 An emulsion, properties and uses.

5.6 First-hand investigation: 245 Soap as an emulsion.

5.11 Environmental impacts of 249 soaps and detergents.

6. The Solvay process

6.5 First-hand investigation: 253 The Solvay process.

6.6 Calculations involving the 257 Solvay process.

6.7 Location of a chemical plant 259 using the Solvay process.

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xvDot Point HSC Chemistry Investigations

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Shipwrecks, Corrosion and Conservation

Shipwrecks, Corrosion and Conservation

1. The ocean as an electrolyte

1.4 Impact of Galvani, Davy, Faraday 263 and electron transfer reactions.

2. Ships of metal

2.2 Conditions for rusting. 267

2.3 First-hand investigation: 269 Corrosion of iron and steel.

2.4 Composition and properties of steel. 273

3. Electrolytic cells

3.3 First-hand investigation: 275 Rate of electrolysis.

4. Corrosion in a marine environment

4.1 History of ship construction 279 materials used.

4.2 First-hand investigation: 281 Corrosion rate of metals and alloys.

4.4 First-hand investigation: 285 Prevention of corrosion.

4.8 Applications of cathodic protection. 289

5. Corrosion in a sunken ship

5.5 First-hand investigation: 291 Rate of corrosion.

5.6 Predicting corrosion rates at depth. 301

6. Corrosion at depth

6.1 First-hand investigation: 303 Rate of corrosion and acidity.

7. Salvage, conservation and restoration of artefacts

7.6 Restoration techniques used in 307 Australian projects.

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Dot Point HSC Chemistry Investigations 1 Production of Materials

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DOT POINT*`Vv>i>

Dot Point HSC Chemistry Investigations2Production of Materials

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Dot Point HSC Chemistry Investigations 3 Production of Materials

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1.3 Identify data, plan and perform a rst-hand investigation to compare the reactivities of appropriate alkenes with the corresponding alkanes in bromine water.

Background information

Alkanes and alkenes are homologous groups of hydrocarbon compounds.

Homologous series of hydrocarbons

General formula

Functional group

Example

Alkane CnH2n+2 CC Ethane

Alkene CnH2n C=C Ethylene (ethene)

Alkanes undergo substitution reactions, e.g.

-

HH C C H + F2

lightHF

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H-- -

-

H

-

H

-

HH C C H +

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F-- -

-

H

-

H

Alkenes undergo addition reactions as they have reactive double bonds, e.g.

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HH C C H + F2

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H--

-

-

-

FH C C H

-

F-- -

-

H

-

H

Bromine water is a yellow-brown colour. As it reacts with a hydrocarbon the yellow-brown colour disappears leaving a clear solution.

You could also conrm your results by testing the alkane and alkene with acidied potassium permanganate solution (KMnO4). Alkenes will decolourise the purple potassium permanganate but alkanes will not react.

Aim: To compare the reactivity of an alkane and an alkene.

Materials

Hints: Label any photographed equipment that you used and add any other items used to the list below.

Four test tubes

Bromine water (BrOH)

Alkane, e.g. cyclohexane (C6H12)

Alkene, e.g. cyclohexene (C6H10)

Potassium permanganate solution (optional)

A fume cupboard

Dot Point HSC Chemistry Investigations4Production of Materials

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Justify the use of these materials.

Hints: Cyclohexane and cyclohexene are both colourless liquids. Is this important here? You could also compare the toxicity and volatility of these cyclic hydrocarbons with similar straight-chain hydrocarbons. Why is bromine water used here? Will it show a different reaction rate for an alkane and an alkene?

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Hypothesis: Write an hypothesis for this experiment.

Hints: From your theoretical knowledge of alkanes and alkenes, predict which will be more reactive and write this as a statement that can be tested. Your prediction should be an educated guess. For example, would you predict that:

Cyclohexene will react faster and more vigorously with bromine water than cyclohexane. Or that: Cyclohexane will react faster and more vigorously with bromine water than cyclohexene?

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Variables: Identify the following variables in this experiment.

Independent variable Dependent variable Variables that must be controlled

Hint: This is the one thing that you change in your experiment. What is different in your test tubes?

Hint: This is what you measure or observe to see the effect of the one change.

Hint: These are the things that stay the same throughout the experiment.

Risk analysis: Before you carry out any activity you must carry out a risk analysis. Complete the table opposite to indicate any risk involved in using the equipment and chemicals involved in this investigation and explain any necessary precaution for this experiment.

The table has been started for you.

Hints: This should acknowledge risks to people carrying out the experiment and also to the broader environment. Think about what the risks are in this activity and how you can remove or reduce these risks.

You will need to look up the relevant Material Safety Data Sheets. Ask your teacher for these if they are not in the laboratory. Are any of the chemicals you will be using toxic or corrosive? Are there regulations for their safe disposal when the experiment is over?

Dot Point HSC Chemistry Investigations 5 Production of Materials

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Chemicals andequipment

Risk Describe the precaution Explain the precaution

Bromine water Toxic and corrosive Use a fume cupboard, goggles and gloves. Work in a well-ventilated area.

Do not discard into the sink. The used bromine water will be mixed with the alkane and alkene, so can be placed in the organic waste disposal.

Prevent toxic substances being inhaled, ingested, splashed into the eyes or contacting the skin.

Toxic substances would enter environment and could enter the food chain and cause poisoning.

Cyclohexane

Cyclohexene

Dot Point HSC Chemistry Investigations6Production of Materials

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Method: Follow the procedure below and note any modications you make.

1. Carry out this procedure in a fume cupboard and wear gloves and safety goggles.

2. Pour 1 mL cyclohexane into each of 2 test tubes labelled A and B.

3. Pour 1 mL cyclohexene into each of 2 test tubes labelled C and D.

4. Cover test tubes A and C so they are in the dark.

5. Place test tubes B and D in the sunlight.

6. Add 5 drops bromine water to each test tube.

7. Tap the side of the test tube gently to mix the contents.

8. Observe any colour change.

If you are going to conrm your results using potassium permanganate, then write the method below.

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