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3 R D E D I T I O N
CHEMISTRY
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Preface xxiiGuided tour for students xxivGuided tour for students and educators xxviGuided tour for educators xxviiiAcknowledgements xxixAbout the Australian authors xxxAbout the American authors xxxii
chapter 1Introduction: Matter and measurement 2
1.1 The study of chemistry 4The atomic and molecular perspective of chemistry 4
Why study chemistry? 5
1.2 Classifications of matter 5States of matter 5
Composition of matter 6
1.3 Properties of matter 8Physical and chemical changes 9
Separation of mixtures 9
1.4 Units of measurement 10SI units 10
A CLOSER LOOK The scientific method 11
Derived SI units 14
1.5 Uncertainty in measurement 16
MY WORLD OF CHEMISTRY Chemistry in the news 16
Precision and accuracy 18
Significant figures 18
Significant figures in calculations 20
STRATEGIES IN CHEMISTRY The importance of practice and estimating answers 21
STRATEGIES IN CHEMISTRY The features of this book 22
Chapter summary and key terms 23Key skills 23Key equations 23Exercises 23
chapter 2Atoms, molecules and ions 28
2.1 Atomic theory of matter 30
2.2 The discovery of atomic structure 31Cathode rays and electrons 31
Radioactivity 32
The nuclear atom 33
2.3 The modern view of atomic structure 34
A CLOSER LOOK Basic forces 36
Atomic numbers, mass numbers and isotopes 36
2.4 Atomic mass 37The atomic mass scale 37
Average atomic masses 38
A CLOSER LOOK The mass spectrometer 39
2.5 The periodic table 39
2.6 Molecules and molecular compounds 42Molecules and chemical formulae 42
Molecular and empirical formulae 42
Picturing molecules 43
2.7 Ions and ionic compounds 44Predicting ionic charges 45
Ionic compounds 46
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MY WORLD OF CHEMISTRY Elements required by living organisms 48
2.8 Naming inorganic compounds 48Names and formulae of ionic compounds 49
Names and formulae of acids 54
Names and formulae of binary molecular compounds 55
2.9 Some simple organic compounds 56Alkanes 56
Some derivatives of alkanes 56
Chapter summary and key terms 58Key skills 59Exercises 59
chapter 3Stoichiometry: Calculations with chemical formulae and equations 66
3.1 Chemical equations 68Balancing equations 68
Indicating the states of reactants and products 70
3.2 Some simple patterns of chemical reactivity 71Combination and decomposition reactions 71
Combustion reactions 74
3.3 Formula mass 75Formula and molecular masses 75
Percentage composition from formulae 76
STRATEGIES IN CHEMISTRY Problem solving 76
3.4 Avogadro’s number and the mole 77Molar mass 78
MY WORLD OF CHEMISTRY Glucose monitoring 80
Interconverting masses and moles 81
Interconverting masses and numbers of particles 82
3.5 Empirical formulae from analyses 83Molecular formulae from empirical formulae 85
Combustion analysis 85
3.6 Quantitative information from balanced chemical equations 87
3.7 Limiting reactants 90Theoretical yields 92
Chapter summary and key terms 94Key skills 95Key equations 95Exercises 96
chapter 4Reactions in aqueous solutions 102
4.1 General properties of aqueous solutions 104Electrolytic properties 104
Ionic compounds in water 105
Molecular compounds in water 106
Strong and weak electrolytes 106
4.2 Precipitation reactions 107Solubility guidelines for ionic compounds 108
Exchange (metathesis) reactions 109
Ionic equations 110
4.3 Acids, bases and neutralisation reactions 112Acids 112
Bases 112
Strong and weak acids and bases 113
Neutralisation reactions and salts 114
Neutralisation reactions with gas formation 116
MY WORLD OF CHEMISTRY Antacids 117
4.4 Oxidation–reduction reactions 118Oxidation and reduction 118
Oxidation numbers 119
Oxidation of metals by acids and salts 120
The activity series 122
A CLOSER LOOK The aura of gold 124
4.5 Concentrations of solutions 125Molarity 125
Expressing the concentration of an electrolyte 126
Interconverting molarity, moles and volume 127
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Dilution 128
MY WORLD OF CHEMISTRY Drinking too much water can kill you 128
4.6 Solution stoichiometry and chemical analysis 130Titrations 131
Chapter summary and key terms 135Key skills 136Key equations 136Exercises 136
chapter 5Nuclear chemistry: Changes within the core of an atom 142
5.1 Radioactivity 144Nuclear equations 144
Types of radioactive decay 145
5.2 Patterns of nuclear stability 147Neutron-to-proton ratio 147
Radioactive series 149
Further observations 149
5.3 Nuclear transmutations 151Accelerating charged particles 151
Reactions involving neutrons 152
Transuranium elements 152
5.4 Rates of radioactive decay 152Radiometric dating 154
Calculations based on half-life 155
5.5 Detection of radioactivity 157Radiotracers 159
5.6 Energy changes in nuclear reactions 159
MY WORLD OF CHEMISTRY Medical applications of radiotracers 160
Nuclear binding energies 162
5.7 Nuclear power: Fission 163Nuclear reactors 164
A CLOSER LOOK The dawning of the nuclear age 166
Nuclear waste 166
5.8 Nuclear power: Fusion 167
5.9 Radiation in the environment and living systems 168Radiation doses 169
Radon 170
MY WORLD OF CHEMISTRY Radiation therapy 170
Chapter summary and key terms 172Key skills 173Key equations 173Exercises 174
chapter 6Electronic structure of atoms 178
6.1 The wave nature of light 180
6.2 Quantised energy and photons 183Hot objects and the quantisation of energy 183
The photoelectric effect and photons 184
6.3 Line spectra and the Bohr model 185Line spectra 186
Bohr’s model 187
The energy states of the hydrogen atom 187
Limitations of the Bohr model 189
6.4 The wave behaviour of matter 189
MY WORLD OF CHEMISTRY Australian Synchrotron 191
The uncertainty principle 191
6.5 Quantum mechanics and atomic orbitals 192Orbitals and quantum numbers 194
6.6 Representations of orbitals 196The s orbitals 196
The p orbitals 198
The d and f orbitals 199
A CLOSER LOOK Probability density and radial probability functions 200
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6.7 Many-electron atoms 200
Orbitals and their energies 200
Electron spin and the Pauli exclusion principle 201
6.8 Electron configurations 202
Hund’s rule 203
Electron configurations 205
Transition metals 206
The lanthanides and actinides 206
6.9 Electron configurations and the periodic table 207Anomalous electron configurations 210
Chapter summary and key terms 212Key skills 213Key equations 213Exercises 213
chapter 7
Periodic properties of the elements 220
7.1 Development of the periodic table 222
7.2 Effective nuclear charge 223
A CLOSER LOOK Effective nuclear charge 225
7.3 Sizes of atoms and ions 225Periodic trends in atomic radii 227
Periodic trends in ionic radii 228
7.4 Ionisation energy 230
Variations in successive ionisation energies 231
Periodic trends in first ionisation energies 232
Electron configurations of ions 234
7.5 Electron affinities 235
7.6 Metals, non-metals and metalloids 236Metals 237
MY WORLD OF CHEMISTRY Ion movement powers electronics 238
Non-metals 241
Metalloids 242
Chapter summary and key terms 243Key skills 244Key equation 244Exercises 244
chapter 8Basic concepts of chemical bonding 250
8.1 Chemical bonds, Lewis symbols and the octet rule 252Lewis symbols 252
The octet rule 252
8.2 Ionic bonding 253Energetics of ionic bond formation 254
Electron configurations of ions of the main-group elements 256
Transition metal ions 257
Polyatomic ions 258
8.3 Covalent bonding 258Lewis structures 258
Multiple bonds 260
8.4 Bond polarity and electronegativity 260Electronegativity 261
Electronegativity and bond polarity 262
Dipole moments 263
Differentiating ionic and covalent bonding 265
8.5 Drawing Lewis structures 267Formal charge 269
A CLOSER LOOK Oxidation numbers, formal charges and actual partial charges 272
8.6 Resonance structures 272
8.7 Exceptions to the octet rule 274Odd number of electrons 275
Less than an octet of valence electrons 275
More than an octet of valence electrons 276
8.8 Strengths of covalent bonds 277Bond enthalpies and the enthalpies of reactions 278
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MY WORLD OF CHEMISTRY Explosives and Alfred Nobel 281
Bond enthalpy and bond length 282
Chapter summary and key terms 284Key skills 284Key equations 285Exercises 285
chapter 9Molecular geometry and bonding theories 292
9.1 Molecular shapes 294
9.2 The VSEPR model 296The effect of non-bonding electrons and multiple bonds on bond angles 300
Molecules with expanded valence shells 301
Shapes of larger molecules 304
9.3 Molecular shape and molecular polarity 305
9.4 Covalent bonding and orbital overlap 307
9.5 Hybrid orbitals 309sp hybrid orbitals 309
sp2 and sp3 hybrid orbitals 311
Hybridisation involving d orbitals 312
Hybrid orbital summary 312
9.6 Multiple bonds 314General conclusions 315
9.7 Molecular orbitals 315The hydrogen molecule 316
Bond order 317
9.8 Second-period diatomic molecules 318Molecular orbitals for Li
2 and Be
2 319
Molecular orbitals from 2p atomic orbitals 319
Electron configurations for B2 to Ne
2 321
A CLOSER LOOK Phases in atomic and molecular orbitals 322
Electron configurations and molecular properties 323
Heteronuclear diatomic molecules 326
Chapter summary and key terms 328Key skills 329Key equations 329Exercises 329
chapter 10Intermolecular forces: Gases 336
10.1 Characteristics of gases 338
10.2 Pressure and its measurement 338
MY WORLD OF CHEMISTRY Blood pressure 340
10.3 The gas laws 341
The pressure–volume relationship: Boyle’s law 341
The temperature–volume relationship: Charles’s law 342
The quantity–volume relationship: Avogadro’s law 342
10.4 The ideal-gas equation 344Relating the ideal-gas equation and the gas laws 346
10.5 Further applications of the ideal-gas equation 348Gas densities and molar mass 348
Volumes of gases in chemical reactions 350
10.6 Gas mixtures and partial pressures 351Partial pressures and mole fractions 352
Collecting gases over water 353
10.7 Kinetic-molecular theory 355Distribution of molecular speed 356
Application of kinetic-molecular theory to the gas laws 357
A CLOSER LOOK The ideal-gas equation 357
10.8 Molecular effusion and diffusion 358Graham’s law of effusion 359
Diffusion and mean free path 361
MY WORLD OF CHEMISTRY Gas separations 362
10.9 Real gases: Deviations from ideal behaviour 362
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The van der Waals equation 364
MY WORLD OF CHEMISTRY Gas pipelines 367
Chapter summary and key terms 367Key skills 368Key equations 368Exercises 369
chapter 11Intermolecular forces: Liquids and solids 376
11.1 A molecular comparison of gases, liquids and solids 378
11.2 Intermolecular forces 380Dispersion forces 381
Dipole–dipole forces 382
Hydrogen bonding 383
Ion–dipole forces 386
Comparing intermolecular forces 387
MY WORLD OF CHEMISTRY Ionic liquids 388
11.3 Some properties of liquids 389Viscosity 389
Surface tension 390
11.4 Phase changes 391Energy changes accompanying phase changes 391
Heating curves 393
Critical temperature and pressure 394
11.5 Vapour pressure 395Explaining vapour pressure at the molecular level 396
Volatility, vapour pressure and temperature 396
Vapour pressure and boiling point 397
A CLOSER LOOK The Clausius–Clapeyron equation 398
11.6 Phase diagrams 398The phase diagrams of H
2O and CO
2 399
11.7 Liquid crystals 401
Types of liquid crystals 401
MY WORLD OF CHEMISTRY Liquid crystal displays 404
11.8 Structures of solids 405Unit cells 405
The crystal structure of sodium chloride 407
Close packing of spheres 409
11.9 Bonding in solids 411Molecular solids 411
A CLOSER LOOK X-ray diffraction by crystals 412
Covalent-network solids 413
Ionic solids 414
Metallic solids 414
Chapter summary and key terms 415Key skills 416Key equations 417Exercises 417
chapter 12Properties of solutions 426
12.1 The solution process 428Energy changes and solution formation 429
Solution formation, spontaneity and disorder 430
Solution formation and chemical reactions 431
A CLOSER LOOK Hydrates 432
12.2 Saturated solutions and solubility 432
12.3 Factors affecting solubility 434Solute–solvent interactions 434
MY WORLD OF CHEMISTRY Fat-soluble and water-soluble vitamins 437
Pressure effects 437
MY WORLD OF CHEMISTRY Blood gases and deep-sea diving 439
Temperature effects 439
12.4 Ways of expressing concentration 440Mass percentage, ppm and ppb 441
Mole fraction, molarity and molality 442
Conversion of concentration units 443
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12.5 Colligative properties 445Lowering the vapour pressure 445
Boiling-point elevation 447
A CLOSER LOOK Ideal solutions with two or more volatile components 448
Freezing-point depression 449
Osmosis 451
Determination of molar mass 454
12.6 Colloids 455Hydrophilic and hydrophobic colloids 456
Removal of colloidal particles 458
Chapter summary and key terms 460Key skills 461Key equations 461Exercises 462
chapter 13Environmental chemistry 468
13.1 Earth’s atmosphere 470Composition of the atmosphere 470
Photochemical reactions in the atmosphere 471
Photoionisation 473
Ozone in the stratosphere 474
13.2 Human activities and Earth’s atmosphere 475The ozone layer and its depletion 475
The troposphere 477
Sulfur compounds and acid rain 477
Nitrogen oxides and photochemical smog 479
Greenhouse gases: Water vapour, carbon dioxide and climate 480
MY WORLD OF CHEMISTRY Methane as a greenhouse gas 482
13.3 Earth’s water 482The global water cycle 483
Salt water: Earth’s oceans and seas 483
Freshwater and groundwater 484
13.4 Human activities and Earth’s water 485Dissolved oxygen and water quality 485
Water purification: Desalination 486
Water purification: Municipal treatment 487
A CLOSER LOOK Water softening 488
The challenges of water purification 488
13.5 Green chemistry 490
Chapter summary and key terms 493Key skills 493Exercises 494
chapter 14Thermodynamics 500
14.1 The nature of energy 502Kinetic energy and potential energy 502
Units of energy 503
System and surroundings 504
Transferring energy: Work and heat 504
14.2 The first law of thermodynamics 505Internal energy 506
Relating DU to heat and work 507
Endothermic and exothermic processes 508
State functions 509
14.3 Enthalpy 510
14.4 Enthalpies of reaction 513
A CLOSER LOOK Using enthalpy as a guide 515
14.5 Calorimetry 516Heat capacity and specific heat capacity 516
Constant-pressure calorimetry 517
Bomb calorimetry (constant-volume calorimetry) 519
14.6 Hess’s law 520
14.7 Enthalpies of formation 523Using enthalpies of formation to calculate enthalpies of reaction 524
14.8 Spontaneous processes 527Seeking a criterion for spontaneity 529
Reversible and irreversible processes 529
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14.9 Entropy and the second law of thermodynamics 531Entropy change 532
DS for phase changes 532
A CLOSER LOOK The entropy change when a gas expands isothermally 533
The second law of thermodynamics 534
14.10 Molecular interpretation of entropy 535Expansion of a gas at the molecular level 535
Boltzmann’s equation and microstates 536
Molecular motions and energy 537
Making qualitative predictions about DS 538
The third law of thermodynamics 541
14.11 Entropy changes in chemical reactions 542Entropy changes in the surroundings 544
14.12 Gibbs free energy (Gibbs energy) 545Standard free energy changes 546
14.13 Gibbs energy and temperature 548
MY WORLD OF CHEMISTRY Driving non-spontaneous reactions 551
Chapter summary and key terms 552Key skills 553Key equations 554Exercises 554
chapter 15Chemical kinetics 564
15.1 Factors that affect reaction rates 566
15.2 Reaction rates 567Change of rate with time 568
Reaction rates and stoichiometry 570
15.3 Concentration and rate laws 571
A CLOSER LOOK Using spectroscopic methods to measure reaction rates 573
Reaction orders: Exponents in the rate law 573
Units of rate constants 575
Using initial rates to determine rate laws 576
15.4 The change of concentration with time (integrated rate equations) 578Zero-order reactions 578
First-order reactions 578
Second-order reactions 580
Half-life 582
MY WORLD OF CHEMISTRY Bromomethane in the atmosphere 582
15.5 Temperature and rate 584The collision model 585
The orientation factor 585
Activation energy 586
The Arrhenius equation 587
Determining the activation energy 588
15.6 Reaction mechanisms 590Elementary reactions 590
Multistep mechanisms 591
Rate laws for elementary reactions 592
The rate-determining step for a multistep mechanism 594
Mechanisms with a slow initial step 595
Mechanisms with a fast initial step 596
15.7 Catalysis 598Homogeneous catalysis 598
Heterogeneous catalysis 600
MY WORLD OF CHEMISTRY Catalytic converters 601
Chapter summary and key terms 603Key skills 604Key equations 604Exercises 605
chapter 16Chemical equilibrium 614
16.1 The concept of equilibrium 616
16.2 The equilibrium constant 618
MY WORLD OF CHEMISTRY The Haber process 619
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Evaluating Kc 620
Equilibrium constants in terms of pressure, KP 621
Equilibrium constants and units 623
16.3 Interpreting and working with equilibrium constants 623The magnitude of equilibrium constants 623
The direction of the chemical equation and K 625
Relating chemical equation stoichiometry and equilibrium constants 625
16.4 Heterogeneous equilibria 627
16.5 Calculating equilibrium constants 629
16.6 Applications of equilibrium constants 631Predicting the direction of reaction 631
Calculating equilibrium concentrations 633
16.7 The equilibrium constant and free energy 635
16.8 Le Châtelier’s principle 638Change in reactant or product concentration 638
Effects of volume and pressure changes 641
Effect of temperature changes 642
The effect of catalysts 644
A CLOSER LOOK Controlling nitric oxide emissions 646
Chapter summary and key terms 647Key skills 648Key equations 648Exercises 648
chapter 17Acid–base equilibria 654
17.1 Acids and bases: A brief review 656
17.2 Brønsted–Lowry acids and bases 656The H1 ion in water 656
Proton-transfer reactions 657
Conjugate acid–base pairs 658
Relative strengths of acids and bases 660
17.3 The autoionisation of water 662
The ion product of water 662
17.4 The pH scale 664
pOH and other ‘p’ scales 665
Measuring pH 667
17.5 Strong acids and bases 668
Strong acids 668
Strong bases 669
17.6 Weak acids 670
Calculating Ka from pH 671
Percent ionisation 673
Using Ka to calculate pH 673
Polyprotic acids 678
17.7 Weak bases 680
Types of weak bases 680
17.8 Relationship between Ka and Kb 683
MY WORLD OF CHEMISTRY Amines and amine hydrochlorides 685
17.9 Acid–base properties of salt solutions 685
An anion’s ability to react with water 686
A cation’s ability to react with water 686
Combined effect of cation and anion in solution 688
17.10 Acid–base behaviour and chemical structure 689
Factors that affect acid strength 689
Binary acids 690
Oxyacids 691
Carboxylic acids 693
A CLOSER LOOK The amphiprotic behaviour of amino acids 694
17.11 Lewis acids and bases 694
Chapter summary and key terms 697
Key skills 698
Key equations 699
Exercises 699
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chapter 18Additional aspects of aqueous equilibria 706
18.1 The common-ion effect 708
18.2 Buffer solutions 711Composition and action of buffer solutions 711
Calculating the pH of a buffer 712
Buffer capacity and pH range 714
Addition of strong acids or bases to buffers 715
MY WORLD OF CHEMISTRY Blood as a buffer solution 716
18.3 Acid–base titrations 717Strong acid–strong base titrations 717
Weak acid–strong base titrations 719
Titrations of polyprotic acids 723
Titrating with an acid–base indicator 724
18.4 Solubility equilibria 725The solubility-product constant, Ksp 726
Solubility and Ksp 727
A CLOSER LOOK Limitations of solubility products 729
18.5 Factors that affect solubility 730Common-ion effect 730
Solubility and pH 731
MY WORLD OF CHEMISTRY Ocean acidification 732
Formation of complex ions 734
MY WORLD OF CHEMISTRY Tooth decay and fluoridation 736
Amphoterism 737
18.6 Precipitation and separation of ions 738Selective precipitation of ions 738
18.7 Qualitative analysis for metallic elements 740
Chapter summary and key terms 743Key skills 744Key equation 744Exercises 745
chapter 19Electrochemistry 752
19.1 Oxidation states and oxidation–reduction equations 754
19.2 Balancing redox equations 756
Half-reactions 756
Balancing equations by the method of half-reactions 756
Balancing equations for reactions occurring in basic solution 759
19.3 Voltaic cells 761
19.4 Cell potentials under standard conditions 764
Standard reduction (half-cell) potentials 766
Strengths of oxidising and reducing agents 771
19.5 Free energy and redox reactions 772
Emf, free energy and the equilibrium constant 774
A CLOSER LOOK Electrical work 776
19.6 Cell potentials under non-standard conditions 776
The Nernst equation 777
Concentration cells 779
MY WORLD OF CHEMISTRY Heartbeats and electrocardiography 780
19.7 Batteries and fuel cells 782
Lead-acid battery 783
Alkaline battery 783
Nickel-cadmium, nickel-metal hydride and lithium-ion batteries 784
Hydrogen fuel cells 784
Direct methanol fuel cells 785
19.8 Corrosion 785
Corrosion of iron (rusting) 786
Preventing the corrosion of iron 787
19.9 Electrolysis 788Quantitative aspects of electrolysis 789
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Chapter summary and key terms 792Key skills 793Key equations 793Exercises 793
chapter 20Chemistry of the non-metals 802
20.1 Periodic trends and chemical reactions 804Chemical reactions 805
20.2 Hydrogen 806Isotopes of hydrogen 807
Properties of hydrogen 807
Preparation of hydrogen 808
Uses of hydrogen 808
A CLOSER LOOK The hydrogen economy 809
Binary hydrogen compounds 809
20.3 Group 18: The noble gases 811Noble gas compounds 811
20.4 Group 17: The halogens 812Properties and preparation of the halogens 813
Uses of the halogens 814
The hydrogen halides 815
Interhalogen compounds 816
Oxyacids and oxyanions 816
20.5 Oxygen 817Properties of oxygen 817
Preparation of oxygen 817
Uses of oxygen 818
Ozone 818
Oxides 819
Peroxides and superoxides 820
20.6 The other group 16 elements: S, Se, Te and Po 821General characteristics of the group 16 elements 821
Occurrence and preparation of S, Se and Te 822
Properties and uses of sulfur, selenium and tellurium 822
Sulfides 822
Oxides, oxyacids and oxyanions of sulfur 823
20.7 Nitrogen 825Properties of nitrogen 825
Preparation and uses of nitrogen 825
Hydrogen compounds of nitrogen 825
MY WORLD OF CHEMISTRY Nitrogen fixation and nitrogenase 827
Oxides and oxyacids of nitrogen 828
MY WORLD OF CHEMISTRY Nitroglycerin and heart disease 829
20.8 The other group 15 elements: P, As, Sb and Bi 830General characteristics of the group 15 elements 830
Occurrence, isolation and properties of phosphorus 831
Phosphorus halides 831
Oxy compounds of phosphorus 831
20.9 Carbon 833Elemental forms of carbon 833
Oxides of carbon 834
MY WORLD OF CHEMISTRY Carbon fibres and composites 834
Carbonic acid and carbonates 835
Carbides 836
Other inorganic compounds of carbon 837
20.10 The other group 14 elements: Si, Ge, Sn and Pb 837General characteristics of the group 14 elements 837
Occurrence and preparation of silicon 838
Silicates 838
Glass 840
Silicones 840
20.11 Boron 841
Chapter summary and key terms 843Key skills 844Exercises 844
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chapter 21Chemistry of the transition metals 850
21.1 Transition metals 852Physical properties 852
Electron configurations and oxidation states 853
Magnetism 854
21.2 Transition metal complexes 856The development of coordination chemistry: Werner’s theory 856
The metal–ligand bond 858
Charges, coordination numbers and geometries 859
21.3 Ligands with more than one donor atom 861Metals and chelates in living systems 863
21.4 Nomenclature and isomerism in coordination chemistry 865
A CLOSER LOOK Entropy and the chelate effect 866
Isomerism 868
Structural isomerism 868
Stereoisomerism 869
21.5 Colour and magnetism in coordination chemistry 872Colour 872
Magnetism of coordination compounds 874
21.6 Crystal-field theory 874
MY WORLD OF CHEMISTRY The battle for iron in living systems 875
Electron configurations in octahedral complexes 879
Tetrahedral and square planar complexes 880
A CLOSER LOOK Charge-transfer colour 882
Chapter summary and key terms 883Key skills 884Exercises 885
chapter 22The chemistry of organic compounds 890
22.1 General characteristics of organic molecules 892The structure of organic molecules 892
The stabilities of organic molecules 892
22.2 An introduction to hydrocarbons 893Alkanes 894
22.3 Applications and physical properties of alkanes 895Homologous series 895
22.4 Structures of alkanes 896
MY WORLD OF CHEMISTRY Petroleum products 897
Hybridisation 898
Alkane shape and conformations 899
Constitutional structural isomers 902
22.5 Alkane nomenclature 903
22.6 Cycloalkanes 906
A CLOSER LOOK Carbon nanotubes 908
22.7 Organic functional groups 909
MY WORLD OF CHEMISTRY Structure–activity relationships 911
22.8 Reactions of alkanes 911Combustion 911
Classification of C and H 913
Free-radical reactions and electron movement 913
A CLOSER LOOK Reactivity by carbon classification 915
Chapter summary and key terms 917Key skills 917Key equations 918Exercises 918
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chapter 23Stereochemistry of organic compounds 926
23.1 Stereochemistry in organic chemistry 928
23.2 Cis–trans isomerism in cycloalkanes 929
23.3 Chirality in organic compounds 931
23.4 Measuring optical activity 933
23.5 Absolute stereochemistry 936Using priority rules to find a stereocentre’s absolute configuration 936
MY WORLD OF CHEMISTRY Chiral drugs 938
23.6 Molecules with more than one stereocentre 940Resolution: Separating enantiomers 942
Chapter summary and key terms 944Key skills 944Key equations 944Exercises 945
chapter 24Chemistry of alkenes and alkynes 952
24.1 The structure of unsaturated hydrocarbons 954The �-bond 954
Bonding in alkenes 955
Bonding in alkynes 957
MY WORLD OF CHEMISTRY Terpenes and isoprene 959
24.2 Isomerism and nomenclature 960Isomerism in alkenes—The E, Z system 961
Alkynes 963
24.3 Arrow notation and resonance structures: Electron counting 963
MY WORLD OF CHEMISTRY The chemistry of vision 964
A CLOSER LOOK Describing charge 965
24.4 Electrophilic addition reactions 966Addition reactions involving HX (X = Cl, Br, I) 967
Addition reactions involving H2O 970
Halogenation: Addition of Br2 and Cl
2 972
Halohydrin formation 973
A CLOSER LOOK Stereochemistry in halohydrin formation 977
24.5 Alkanes from alkenes: Catalytic hydrogenation 977
A CLOSER LOOK Hydrogenation 978
24.6 Addition polymerisation 980Making polymers 981
Structure and physical properties of addition polymers 982
MY WORLD OF CHEMISTRY Recycling plastics 984
MY WORLD OF CHEMISTRY The accidental discovery of Teflon® 985
MY WORLD OF CHEMISTRY Vulcanisation 986
Chapter summary and key terms 987Key skills 988Key equations 988Exercises 988
chapter 25Alcohols, haloalkanes and ethers 994
25.1 Alcohols: Structure, properties and nomenclature 996
MY WORLD OF CHEMISTRY Vitamin D 998
Common alcohols 999
MY WORLD OF CHEMISTRY The solubility nexus 1000
Naming alcohols 1001
Classifying alcohols 1003
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25.2 Haloalkanes 1004
25.3 Ethers: Structure, properties and nomenclature 1006
Naming ethers 1007
A CLOSER LOOK Crown ethers 1008
25.4 Reactions of alcohols 1009Alkoxides 1009
Basicity of alcohols 1010
Alcohols to haloalkanes 1010
Dehydration of alcohols 1011
25.5 Nucleophilic substitution reactions of haloalkanes 1011
A CLOSER LOOK Molecularity 1014
25.6 Haloalkanes to alkenes: b-elimination 1015
25.7 Substitution versus elimination 1018
A CLOSER LOOK Nucleophile or Lewis base? 1019
E1 and SN1 reactions 1020
MY WORLD OF CHEMISTRY Polymerisation versus macrocyclisation 1023
Chapter summary and key terms 1024Key skills 1025Key equations 1025Exercises 1025
chapter 26Aldehydes, ketones and carbohydrates 1034
26.1 Aldehydes, ketones and the carbonyl group 1036
26.2 Preparation of aldehydes and ketones 1039Oxidation of 1° and 2° alcohols 1040
Ozonolysis 1041
26.3 Reactions of aldehydes and ketones 1042Addition of carbon nucleophiles—Grignard reactions 1042
Addition of nitrogen and oxygen nucleophiles: Formation of imines and acetals 1045
Reduction reactions 1048
Cyanohydrins 1049
Tautomerism in aldehydes and ketones 1051
Halogenation of aldehydes and ketones 1053
26.4 Carbohydrates 1054Monosaccharides 1054
Cyclic versus open-chain structures 1057
MY WORLD OF CHEMISTRY Glucosamine 1058
Oligosaccharides and polysaccharides 1060
MY WORLD OF CHEMISTRY Cyclodextrins 1062
MY WORLD OF CHEMISTRY Vitamin C 1065
Chapter summary and key terms 1067Key skills 1067Key equations 1067Exercises 1068
chapter 27Carboxylic acids and their derivatives 1076
27.1 Carboxylic acids 1078Structure, properties and nomenclature 1078
Acidity 1081
27.2 Preparation of carboxylic acids 1084
27.3 Esters and esterification 1086
27.4 Fats, oils and waxes 1090Soaps and detergents 1093
27.5 Acid chlorides, anhydrides and nucleophilic acyl substitution 1095
MY WORLD OF CHEMISTRY Steroids 1096
Nucleophilic acyl substitution 1098
27.6 Condensation polymerisation 1100
MY WORLD OF CHEMISTRY Bindeez 1101
MY WORLD OF CHEMISTRY Towards the plastic car 1103
Polymers for medicine 1104
MY WORLD OF CHEMISTRY Biodegradable sutures 1105
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xx Chemistry: the central science
Chapter summary and key terms 1107Key skills 1107Key equations 1107Exercises 1108
chapter 28Benzene and its derivatives 1114
28.1 The structure of benzene 1116Bonding in benzene 1116
28.2 Isomerism and nomenclature in aromatic compounds 1117
MY WORLD OF CHEMISTRY The discovery of liquid crystals 1119
Phenols 1121
28.3 Resonance and aromaticity 1122Aromaticity 1123
28.4 Acidity of alcohols and phenols 1124
28.5 Electrophilic aromatic substitution (EAS) reactions 1127Directing groups and substitution effects 1129
A CLOSER LOOK Organic dyes 1130
Chapter summary and key terms 1138Key skills 1139Key equations 1139Exercises 1139
chapter 29Nitrogen-containing organic compounds 1146
29.1 Amines and the amide bond 1148Amines 1148
MY WORLD OF CHEMISTRY Amines and amine hydrochlorides 1152
Reactivity of amines 1154
Synthesis of amines 1157
Amides 1159
29.2 Amino acids 1161Acid–base properties 1165
A CLOSER LOOK Sickle-cell anaemia 1166
Reactions involving amino acids 1170
29.3 Proteins, peptides and enzymes 1172Coding peptides 1172
Protein structure 1175
Enzymes 1177
Sequencing of peptides and proteins 1179
MY WORLD OF CHEMISTRY B group vitamins 1181
29.4 Nucleic acids and DNA 1182
Chapter summary and key terms 1189Key skills 1190Key equations 1190Exercises 1190
chapter 30Solving molecular structure 1198
30.1 The electromagnetic spectrum 1200
A CLOSER LOOK Using spectroscopic methods to measure reaction rates 1202
30.2 Infrared (IR) spectroscopy 1202The spring model 1203
Measuring IR spectra 1204
MY WORLD OF CHEMISTRY IR spectroscopy for biological imaging 1209
30.3 Nuclear magnetic resonance (NMR) spectroscopy 1210Nuclear magnetic resonance frequencies 1212
MY WORLD OF CHEMISTRY Nuclear spin and magnetic resonance imaging 1213
The chemical shift 1214
Sample preparation 1215
Interpreting NMR spectra 1216
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detailed contents xxi
Integration 1220
Spin–spin coupling 122113C NMR spectra 1224
30.4 Mass spectrometry 1226Electron impact ionisation mass spectrometry 1226
Interpreting mass spectra 1228
30.5 Compound identification using spectra 1232Deducing the molecular formula of an organic compound 1232
Chemical wet testing: Tests for functional groups 1234
Chapter summary and key terms 1237Key skills 1238Key equations 1238Exercises 1239
Appendices A Mathematical operations 1252
B Properties of water 1258
C Thermodynamic quantities for selected substances at 298.15 K (25 °C) 1259
D Aqueous equilibrium constants 1262
E Standard reduction potentials at 25 °C 1264
Answers to Concept Checks 1265
Answers to Figure it Out 1274
Glossary 1280
Index 1296
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preface
Philosophy
This is the third Australian edition of a text that has enjoyed significant global success over a number of decades. Our original aim in adapting Chemistry: The Central Science for a wider market was to ensure that the text remained a central, indispensable learning tool for the student of chemistry. In this book we aim to provide a comprehensive coverage of all aspects of chemistry that may be used at introductory university level. It will provide students with the depth of knowledge they require in their first-year undergraduate curriculum and to arm chemistry academics across Austra-lia with a broad and balanced view of chemistry with which to set their curricula. Throughout the text we have maintained a conversational style of explaining information rather than simply stating facts. We have found that this style has been highly appreciated by the student.
Organisation and Contents
In this edition the first four chapters give a largely macroscopic overview of chemistry. The basic concepts presented—such as atomic structure, the nature of chemical reactions, stoichiometry, measurement and quantification and the main types of reaction in aqueous solution—provide a necessary background for many of the laboratory experiments usually performed in first year general chemistry.
The following five chapters (Chapters 5–9) focus on the atomic scale, starting with the transformations that occur within the nucleus of an atom before moving on to deal with the electronic structure of the atom, the consequent effects on the properties of the elements and the basic theories of chemical bonding and molecular geometry. Chapters 10 and 11 consider the macroscopic properties of the three states of matter—gas, liquid and solid—and the forces which influence their behaviour. A more detailed look at solubility and solutions and our interaction with the atmosphere and oceans are examined in the next two chapters (Chapters 12 and 13). All chemical reactions involve energy changes and Chapter 14 comprehensively covers the thermodynamic processes operating in all chemical reactions.
The next several chapters examine the factors that determine the speed and extent of chemical reactions: kinetics (Chapter 15) and equilibria (Chapters 16–18). These are followed by electro-chemistry, which discusses the use of chemical reactions to produce electrical energy and vice versa (Chapter 19). Chapters 20 and 21 introduce the chemistry of non-metals, metals and coordination compounds. Throughout Chapters 1–21 there are extensive areas of modern chemistry that are dealt with broadly. For example, we introduce students to descriptive inorganic chemistry by integrating examples throughout the text. You will find pertinent and relevant examples of organic and inorganic chemistry woven into all chapters as a means of illustrating principles and applica-tions and the relationship between all areas of chemistry. Some chapters, of course, more directly address the properties of elements and their compounds, especially Chapters 7, 20 and 21.
Organic chemistry is central to all living things and Chapters 22–30 lead us on a journey from elementary hydrocarbons to elaborate bioorganic molecules. Much of what we discuss is treated
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Preface xxiii
from a fundamental level so your transition to tertiary studies in organic chemistry is smooth and rapid. We place emphasis on the core reactions observed in organic chemistry and treated many cases mechanistically. This fosters a deep understanding of why organic molecules react in the way they do thereby giving you an opportunity to understand much more chemistry than is discussed. Chapter 22 provides a foundation to our examination of organic chemistry by using hydrocarbons to illustrate how we represent and name organic molecules. It goes on to provide an overview of the functional groups—the reactive parts of the molecule—on which we build our understanding of organic chemistry. The shape of a molecule may be pivotal in determining its reactivity, particularly in a biological context, and Chapter 23 leads to an in-depth discussion of stereochemistry.
The next six chapters cover the fundamental reactions encountered in organic chemistry, at each step building to the application of these reaction in a modern world (for example, polymerisation in Chapters 24 and 27) and their essential role in the chemistry of life (for example, carbohydrates in Chapter 26, fats in Chapter 27, proteins and nucleic acids in Chapter 29). Chapter 28 investigates aromatic compounds as a separate class. Here it is important for the student to note the differences in reactivity to the alkenes studied in Chapter 24.
Finally, Chapter 30 stands alone as a reference guide to mass spectrometry, NMR spectroscopy and IR spectroscopy. Whether these topics are taught with much emphasis on the technology is up to the instructor. What we believe is most important is students’ development at complex problem-solving, bringing two or more concepts together to draw a logical conclusion. The approach to solving molecular structure also confirms their knowledge of the basic principles of organic chemistry, bonding, functional groups and drawing structural formulae. Our coverage of organic chemistry gives students a unique perspective and challenges the very ‘standard format’ often seen in a first-year text.
Our topic sequence provides a logical progression through chemistry, but we recognise that not everyone teaches all the topics in exactly the order we have chosen. We have therefore made sure that instructors can make common changes in teaching sequence with no loss in student comprehension. In particular, many instructors prefer to introduce gases (Chapter 10) after stoichiometry or after thermochemistry rather than with states of matter. The chapter on gases has been written to permit this change with no disruption in the flow of material. It is also possible to treat the balancing of redox equations (Sections 19.1 and 19.2) earlier, after the introduction of redox reactions in Section 4.4. Finally, some instructors like to cover organic chemistry (Chapters 22 to 30) earlier than its position in this text. Throughout the text we have introduced linkages (indicated by the symbol •) to sections in other parts of the book. This allows the reader to quickly find relevant material and highlights the integrated nature of chemistry. A glossary of terms provides succinct definitions for quick reference and a comprehensive index ensures the extensive information contained in this book is easily accessible.
s Steven Langford School of ChemistryMonash University, Clayton VIC [email protected]
s Dalius Sagatys Science and Engineering FacultyQueensland University of Technology, Brisbane QLD [email protected]
s Adrian George School of ChemistryUniversity of Sydney, NSW [email protected]
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guided tour for students
MAKING CONNECTIONS
The 3rd edition of Chemistry: The Central Science includes several key features to help you see the bigger picture: to move beyond memorisation and have a deeper understanding of the relationships between concepts in chemistry.
Making connections across different topics
New enhanced blue links • are featured in the margins and include voice balloons which direct you to other relevant sections that will enrich your understanding of the current topic.
Making connections between chemistry and the real world
My World of Chemistry
Chemistry occurs all around us, throughout every day. Recognising the importance of chemistry in your daily life can improve your understanding of chemical concepts. My World of Chemistry showcases chemistry’s connection to world events, scientific discoveries, and medical breakthroughs throughout the text.
Making connections visually
Micro to Macro Art
These illustrations offer three parts: a macroscopic image (what you can see with your eyes); a molecular image (what the molecules are doing); and a symbolic representation (how chemists represent the process with symbols and equations).
A new intermediate step has been added, showing where chemistry occurs in the problem-solving process.
*NEW* Figure It Out questions and Voice Balloons
Figure It Out questions encourage you to stop and analyse the artwork in the text, for conceptual understanding. ‘Voice Balloons’ in selected figures help you break down and understand the components of the image.
GLUCOSE MONITORING
Over 1 million Australians (although estimatesvary) have diabetes, and globally the number ap-
proaches 172 million. Diabetes is a metabolicdisorder in which the body either cannot pro-
duce or cannot properly use the hormoneinsulin. One signal that a person is diabetic
is that the concentration of glucose in the blood is higher thannormal. Therefore, people who are diabetic need to measuretheir blood glucose concentrations regularly. Untreated dia-betes can cause severe complications such as blindness andloss of limbs.
The body converts most of the food we eat into glucose.After digestion, glucose is delivered to cells via the blood.Cells need glucose to live, and insulin must be present in orderfor glucose to enter the cells. Normally, the body adjusts theconcentration of insulin automatically, in concert with the
MY WORLD OF CHEMISTRYglucose concentration after eating. However, in a diabeticperson, either little or no insulin is produced (Type 1 diabetes)or insulin is produced but the cells cannot take it up properly(Type 2 diabetes). The result is that the blood glucose concen-tration is too high. People normally have a range of 70–120 mgglucose per litre of blood. A person who has not eaten for 8hours or more is diagnosed as diabetic if his or her glucoselevel is 1260 mg dm-3 or higher.
Glucose meters work by the introduction of blood from aperson, usually by a prick of the finger, onto a small strip ofpaper that contains chemicals that react with glucose. Inser-tion of the strip into a small battery-operated reader gives theglucose concentration. The mechanism of the readout variesfrom one monitor to another—it may be a measurement of asmall electrical current or measurement of light produced in achemical reaction. Depending on the reading on any givenday, a diabetic person may need to receive an injection ofinsulin or simply stop eating sweets for a while.
�
�
�
��
�
�
�
�
��
� � ��
(a) (b)
At end point, purple colour of MnO4
� remains because all C2O4
2� consumed
The purple colour of MnO4�
disappears immediately as reaction with C2O4
2� occurs
MnO4�(aq)
C2O42�(aq)
F I G U R E I T O U T
Which species is reduced in this reaction? Which species is the reducing agent?
« FIGURE 19.2 Titration of an acidicsolution of Na2C2O4 with KMnO4(aq).
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• Review this on page xx
Project2_Layout 1 4/06/13 2:26 PM Page 1
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guided tour for students xxv
Making connections to problem-solving and critical thinking skills
Analyse/Plan/Solve/Check
This four-step problem-solving method helps you understand what you are being asked to solve, to plan how you will solve each problem, to work your way through the solution, and to check your answers. This method is introduced in Chapter 3 and reinforced throughout the book.
Dual-Column Problem-Solving Strategies
Found in Selected Sample Exercises, these strategies explain the thought process involved in each step of a mathematical calculation using a unique layout for clarity. They help you develop a conceptual understanding of those calculations.
Strategies in Chemistry
Strategies in Chemistry teach ways to analyse information and organise thoughts, helping to improve your problem-solving and critical-thinking abilities.
126 CHAPTER 4 Reactions in Aqueous Solution
SAMPLE EXERCISE 4.10 Calculating molar concentrations of ions
What are the molar concentrations of each of the ions present in a 0.025 M aqueoussolution of calcium nitrate?
SOLUTIONAnalyse We are given the concentration of the ionic compound used to make the so-lution and asked to determine the concentrations of the ions in the solution.
Plan We can use the subscripts in the chemical formula of the compound to deter-mine the relative ion concentrations.
Solve Calcium nitrate is composed of calcium ions (Ca2+) and nitrate ions (NO3-), so
its chemical formula is Ca(NO3)2. Because there are two NO3–ions for each Ca2+ ion
in the compound, each mole of Ca(NO3)2 that dissolves dissoci ates into 1 mol ofCa2+ and 2 mol of NO3
-. Thus, a solution that is 0.025 M in Ca(NO3)2 is 0.025 M in Ca2+
and 2 : 0.025 M = 0.050 M in NO3-.
Check The concentration of NO3- ions is twice that of Ca2+ ions, as the subscript 2
after the NO3- in the chemical formula Ca(NO3)2 suggests it should be.
SAMPLE EXERCISE 4.9 Calculating molarity
Calculate the molarity of a solution made by dissolving 23.4 g of sodium sulfate (Na2SO4) in enough water to form 125 cm3 of solution.
SOLUTIONAnalyse We are given the number of grams of solute (23.4 g), its chemical formula (Na2SO4) and the volume ofthe solution (125 cm3) and asked to calculate the molarity ofthe solution.
Plan We can calculate molarity using Equation 4.33. To do so,we must convert the grams of solute to moles and the volumeof the solution from millilitres to litres.
obtained by dividing its mass by its molar mass: Moles Na2SO4 =23.4 g
142 g mol-1 = 0.165 mol
Converting the volume of the solution to litres: Litres solution = a 1251000 b dm3 = 0.125 dm3
Thus the molarity is MMolarity = 0.165 mol0.125 dm3 = 1.32 mol
dm3 = 1.32
PRACTICE EXERCISECalculate the molarity of a solution made by dissolving 5.00 g of glucose (C6H12O6) in sufficient water to form exactly 100 cm3 of solution.Answer: 0.278 M(See slso Exercises 4.45, 4.46.)
Solve The number of moles of Na2SO4 is
Expressing the Concentration of an ElectrolyteWhen an ionic compound dissolves the relative concentrations of the ionsintroduced into the solution depend on the chemical formula of the compound.For example, a 1.0 M solution of NaCl is 1.0 M in Na+ ions and 1.0 M in Cl- ions.Similarly, a 1.0 M solution of Na2SO4 is 2.0 M in Na+ ions and 1.0 M in SO4
2- ions.Thus, the concentration of an electrolyte solution can be specified either interms of the compound used to make the solution (1.0 M Na2SO4) or in terms ofthe ions that the solution contains (2.0 M Na+ and 1.0 M SO4
2-).
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PRACTICE EXERCISECalculate the formula mass of (a) Al(OH)3 and (b) CH3OH.Answers: (a) 78.0 u, (b) 32.0 u (See also Exercises 3.17, 3.18.)
Percentage Composition from FormulaeOccasionally we must calculate the percentage composition of a compound (thatis, the percentage by mass contributed by each element in the substance). Forexample, in order to verify the purity of a compound, we may wish to comparethe calculated percentage composition of the substance with that found experi-mentally. Calculating percentage composition is a straightforward matter if thechemical formula is known.
76 CHAPTER 3 Stoichiometry: Calculations with Chemical Formulae and Equations
[3.10]=
number of atomsof that element
* atomic massof the element
formula mass of the compound* 100%% Element
learnt earlier. Recognise that some data may not be given explic-itly in the problem; you may be expected to know certain quanti-ties (such as Avogadro’s number) or look them up in tables (suchas atomic masses). Recognise also that your plan may involveeither a single step or a series of steps with intermediate answers.
Step 3: Solve the problem. Use the known information andsuitable equations or relationships to solve for the unknown.Be careful with significant figures, signs and units.
Step 4: Check the solution. Read the problem again to makesure you have found all the solutions asked for in the problem.Does your answer make sense? That is, is the answer outra-geously large or small or is it in the ballpark? Finally, are theunits and significant figures correct?
PROBLEM SOLVING
Practice is the key to success in solving problems.As you practise, you can improve your skills by
following these steps.
Step 1: Analyse the problem. Read theproblem carefully. What is it asking you to
do? What information does it provide you with? List both thedata you are given and the quantity you need to obtain (theunknown).
Step 2: Develop a plan for solving the problem. Consider apossible path between the given information and the unknown.This is usually a formula, an equation or some principle you
STRATEGIES IN CHEMISTRY
(b) If a chemical formula has parenthe-ses, the subscript outside the paren-theses is a multiplier for all atomsinside. Thus for Ca(NO3)2, we have
164.1 u
1 Ca atom = 1(40.1 u) = 40.1 u2 N atoms = 2(14.0 u) = 28.0 u6 O atoms = 6(16.0 u) = 96.0 u
SAMPLE EXERCISE 3.6 Calculating percentage composition
Calculate the percentage of carbon, hydrogen and oxygen (by mass) in C12H22O11.
SOLUTIONAnalyse We are given a chemical formula which shows the elements and the num-ber of atoms of each element in the molecule.
Plan We see that Equation 3.10 relates % composition of an element in a molecule tothe number of atoms of each element, the atomic mass of each element and the for-mula mass of the molecule. The formula mass can be calculated as in Exercise 3.5 andthe atomic masses can be obtained from the periodic table.
Solve Using Equation 3.10 and the periodic table to obtain atomic masses, we have
%C =(12)(12.0 u)
342.0 u* 100% = 42.1%
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80 CHAPTER 3 Stoichiometry: Calculations with Chemical Formulae and Equations
The entries in Table 3.2 for N and N2 point out the importance of stating thechemical form of a substance exactly when we use the mole concept. Supposeyou read that 1 mol of nitrogen is produced in a particular reaction. You mightinterpret this statement to mean 1 mol of nitrogen atoms (14.0 g). Unless other-wise stated, however, what is probably meant is 1 mol of nitrogen molecules,N2 (28.0 g), because N2 is the usual chemical form of the element. To avoidambiguity, it is important to state explicitly the chemical form being discussed.Using the chemical formula N2 avoids ambiguity.
SAMPLE EXERCISE 3.9 Calculating molar mass
What is the molar mass of glucose, C6H12O6?
SOLUTIONAnalyse We are given a molecular formula which gives us the types of atoms andtheir number in the molecule.
Plan The molar mass of any substance is numerically equal to its formula masswhich will have units of u, whereas the molar mass will have units of g mol-1. Weproceed as in Sample Exercise 3.5.
Solve Our first step is to determine the formula mass of glucose.
Because glucose has a formula mass of 180.0 u, one mole of this substance has a massof 180.0 g. In other words, C6H12O6 has a molar mass of 180.0 g mol-1.
Check The magnitude of our answer seems reasonable, and g mol-1 is the appropri-ate unit for the molar mass.
Comment Glucose is sometimes called dextrose. Also known as blood sugar, glu-cose is found widely in nature, occurring, for example, in honey and fruits. Othertypes of sugars used as food are converted into glucose in the stomach or liver beforethey are used by the body as energy sources. Because glucose requires no conversion,it is often given intravenously to patients who need immediate nourishment.
PRACTICE EXERCISECalculate the molar mass of Ca(NO3)2.Answer: 164.1 g mol-1
(See also Exercise 3.27.)
6 C atoms = 6(12.0 u) = 72.0 u12 H atoms = 12(1.0 u) = 12.0 u6 O atoms = 6(16.0 u) = 96.0 u
180.0 u
GLUCOSE MONITORING
Over 1 million Australians (although estimatesvary) have diabetes, and globally the number ap-
proaches 172 million. Diabetes is a metabolicdisorder in which the body either cannot pro-
duce or cannot properly use the hormoneinsulin. One signal that a person is diabet-
ic is that the concentration of glucose in the blood is higherthan normal. Therefore, people who are diabetic need tomeasure their blood glucose concentrations regularly. Un-treated diabetes can cause severe complications such as blind-ness and loss of limbs.
The body converts most of the food we eat into glucose.After digestion, glucose is delivered to cells via the blood.Cells need glucose to live, and insulin must be present inorder for glucose to enter the cells. Normally, the body adjuststhe concentration of insulin automatically, in concert with the
MY WORLD OF CHEMISTRYglucose concentration after eating. However, in a diabeticperson, either little or no insulin is produced (Type 1 diabetes)or insulin is produced but the cells cannot take it up properly(Type 2 diabetes). The result is that the blood glucose concen-tration is too high. People normally have a range of 70–120 mgglucose per decilitre (ddm3) of blood. A person who has noteaten for 8 hours or more is diagnosed as diabetic if his or herglucose level is 126 mg ddm-3 or higher.
Glucose meters work by the introduction of blood from aperson, usually by a prick of the finger, onto a small strip ofpaper that contains chemicals that react with glucose. Inser-tion of the strip into a small battery-operated reader gives theglucose concentration. The mechanism of the readout variesfrom one monitor to another—it may be a measurement of asmall electrical current or measurement of light produced in achemical reaction. Depending on the reading on any givenday, a diabetic person may need to receive an injection ofinsulin or simply stop eating sweets for a while.
*Brown 3e - ch03 (India).QXD_BLB03_038-075 4/03/13 2:39 PM Page 80
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