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  • SACE TWO - AUSTRALIAN CURRICULUM

    CHEMISTRY

    WORKBOOKFIRST EDITION

    GLEN ARTHURRHYS LEWIS

  • PUBLISHING INFORMATION

    This Workbook is part of the Essentials series, designed to support the teaching of SACE Stage 1 and 2 subjects in South Australia. It is specially designed to meet the requirements of the SACE Stage 2 Australian Curriculum Chemistry.

    The Essentials Education series is published by Adelaide Tuition Centre, 21 Fourth Street, Bowden 5007.TELEPHONE (08) 8241 5568 FACSIMILE (08) 8241 5597

    LIBRARY CATALOGUE:

    Arthur; Glen - Lewis; Rhys1. Chemistry, SACE2 Australian Curriculum - 2. Essentials Workbook

    ISBN - 978-1-925505-05-4

    First edition 2017. Copyright Adelaide Tuition Centre 2017.

    COPYRIGHT INFORMATION

    The copyright of the text of this book remains the property of the authors and the copyright of the diagrams and cartoons belongs to the publisher. All rights are reserved except under the conditions described in the Copyright Act 1968 of Australia and subsequent amendments. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior permission of the publisher. While every care has been taken to trace and acknowledge copyright, the publishers tender apologies for any accidental infringement where copyright has proved traceable.

    THE AUTHORSGlen Arthur B.Ed. (Secondary Maths/Science), MRACI

    Glen has taught senior Chemistry at Stage 1 and Stage 2 for over 20 years. He has taught in both the public and independent school sectors over this time.

    He has extensive experience in the development of materials, curriculum, and assessment for the SACE Board of South Australia. He is a member of the SACE Curriculum Leaders Group for Chemistry. He is an active member of the Royal Australian Chemical Institute, in the Chemical Education Division. He is also involved in the delivery of Chemistry Curriculum and Methodology in the School of Education, at the University of Adelaide. He also has over a decade of experience in teaching, moderation, and marking for the Foundation Studies Program in Chemistry, in conjunction with the South Australian Universities.

    Glen is a passionate educator, dedicated to developing the potential of students and Chemistry educators.

    Rhys Lewis B.Sc., Grad.Dip.Ed.

    Rhys has been a teacher of science for seven years in South Australia. He has taught hundreds of Stage 1 and 2 students in chemistry, physics, and biology. Rhys was Regional winner of the SA Public Teaching Awards in 2013 and winner of a National excellence in teaching award in 2014. He is also co-author of the SACE1 Essentials Chemistry Workbook. Rhys excels in his ability to communicate scientific concepts in an engaging, clear, and concise manner.

  • Essentials Education

    TABLE OF CONTENTS

    Table of ContentsPreface

    Topic One: Monitoring the Environment1.1 Global Warming and Climate Change1.2 Photochemical Smog1.3 Volumetric Analysis1.4 Chromatography1.5 Atomic SpectroscopySummary Test One: Monitoring the Environment

    Topic Two: Managing Chemical Processes2.1 Rates of Reactions2.2 Equilibrium and Yield2.3 Optimising ProductionSummary Test Two: Managing Chemical Processes

    Topic Three: Organic and Biological Chemistry3.1 Introduction3.2 Alcohols3.3 Aldehydes and Ketones3.4 Carbohydrates3.5 Carboxylic Acids3.6 Amines3.7 Esters3.8 Amides3.9 Triglycerides3.10 ProteinsSummary Test Three: Organic and Biological Chemistry

    Topic Four: Managing Resources4.1 Energy4.2 Water4.3 Soil4.4 MaterialsSummary Test Four: Managing Resources

    SolutionsTopic One: Monitoring the EnvironmentTopic Two: Managing Chemical ProcessesTopic Three: Organic and Biological ChemistryTopic Four: Managing Resources

    AppendicesAppendix 1: The Periodic Table of the ElementsAppendix 2: SI prefixes, symbols and values

  • Essentials Education56

    STAGE 2 CHEMISTRY TOPIC 3: ORGANIC AND BIOLOGICAL CHEMISTRY

    3.9 TriglyceridesDraw the structural formula of an edible oil or fat, given the structural formula(e) of the carboxylic acid(s) from which it is derived.

    SACE 2016

    Fatty acids are carboxylic acids that have long (4 to 28 carbon atoms) hydrocarbon chains (Figure 3.89). The hydrocarbon chain of a fatty acid is either saturated (single carboncarbon bonds only) or unsaturated (at least one carboncarbon double or triple bond).

    Figure 3.89: Saturated and unsaturated fatty acid molecules.

    Fatty acids with one double or triple bond are termed monounsaturated. Fatty acids with more than one double or triple bond are termed polyunsaturated. Glycerol (propane1,2,3triol) is a small alcohol with three hydroxyl groups (Figure 3.90).

    Figure 3.90: Glycerol (propane1,2,3triol).

    Glycerol (alcohol) reacts with three fatty acid (carboxylic acid) molecules to form an ester called a triglyceride. Three molecules of water are formed in each reaction (Figure 3.91).

    Figure 3.91: Formation of a triglyceride.

  • Essentials Education 57

    TOPIC 3

    3

    TRIGLYCERIDES

    In many cases, the three fatty acid molecules that combine and form the triglyceride are identical. However, three different fatty acid molecules can form one triglyceride molecule. Figure 3.92 shows a triglyceride formed in the reaction of glycerol with stearic acid, linoleic acid, and palmitic acid.

    Figure 3.92: Triglyceride formed from three different fatty acids.

    Triglyceride molecules are often represented using a partially condensed structural formula. Figure 3.93 shows the partially condensed structural formula of triglyceride shown in Figure 3.92.

    Figure 3.93: Partially condensed structural formula of the triglyceride molecule shown in Figure 3.92.

    Question

    50. Draw the structural formula of the triglyceride formed from the fatty acids below.

    CH3(CH2)16COOH CH3(CH2)5CH=CH(CH2)7COOH CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH

    (2 marks) KA4

  • Essentials Education58

    STAGE 2 CHEMISTRY TOPIC 3: ORGANIC AND BIOLOGICAL CHEMISTRY

    Identify and draw the structural formulae of the alcohol and acid(s) from which a triglyceride is derived, given its structural formula.

    SACE 2016

    Triglycerides are esters that undergo hydrolysis in acidic or alkaline solution. Three fatty acids and glycerol are formed when a triglyceride is hydrolysed in an acidic solution (Figure 3.94).

    Figure 3.94: Hydrolysis of a triglyceride molecule in an acidic solution.

    Three carboxylate anions are formed when the triglyceride is hydrolysed in an alkaline solution (Figure 3.95).

    Figure 3.95: Hydrolysis of a triglyceride molecule in an alkaline solution.

    The hydrolysis of a triglyceride occurs inside the cells of living organisms including animals and plants. The hydrolysis reaction is catalysed by a class of enzymes called lipases. Lipases are present in the saliva and other digestive secretions inside the human body. The role of lipases is to rapidly break down triglycerides into fatty acids that can be used for a variety of functions from energy production to the maintenance of the immune, circulatory and nervous systems.

    Question

    51. Draw the structural formula of the three fatty acids formed in the hydrolysis of the triglyceride below.

    (6 marks) KA4

  • Essentials Education 59

    TOPIC 3

    3

    TRIGLYCERIDES

    Describe and explain the use of a solution of bromine or iodine to determine the degree of unsaturation of a compound. Draw the structural formula of the reaction product.

    Explain how the degree of unsaturation causes differences in the melting points of edible oils and fats.

    SACE 2016

    Edible fats and oils are mixtures of organic compounds that contain a high proportion of triglycerides. Edible fats are distinguished from edible oils by their melting points. Edible fats are solid at standard laboratory temperature (25C) whereas edible oils are liquid.

    Edible fatsEdible fats are solid mixtures containing a higher concentration of saturated fats when compared with edible oils. Saturated fats are triglyceride molecules containing only saturated fatty acids (Figure 3.96).

    Figure 3.96: Structural formulae of a saturated fat.

    Saturated fats are derived from animals and plants. Land animals contain a higher percentage of saturated fats than marine animals. Some vegetable products, including coconut oil and palm kernel oil, are higher in saturated fat than fat derived from any land animal.

    Edible oilsEdible oils are liquid mixtures containing a higher concentration of unsaturated fats when compared with edible fats. Unsaturated fats are triglyceride molecules containing one or more unsaturated fatty acids (Figure 3.97).

    Figure 3.97: Structural formulae of an unsaturated fat.

    Unsaturated fats are derived from animals and plants. Fish contain many different unsaturated (omega3) fats which are an essential components of the human brain. Most edible oils are derived from plants.

  • Essentials Education60

    STAGE 2 CHEMISTRY TOPIC 3: ORGANIC AND BIOLOGICAL CHEMISTRY

    Material Source Saturated fat (% of total fat)Unsaturated fat (% of total fat)

    Coconut oil Plant 92 8

    Palm kernel oil Plant 86 14

    Butter fat Animal 66 34

    Beef fat Animal 52 48

    Palm oil Plant 51 49

    Cottonseed oil Plant 27 73

    Olive oil Plant 15 85

    Sunflower oil Plant 10 90

    Melting pointsThe melting points of edible fats and oils are dependent on the strengths of the intermolecular forces between triglyceride molecules. Edible fats are solid at standard laboratory temperature (25C) as the melting point is greater than 25C. The higher melting points of edible fats are attributed to the greate