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Chemistry: the Central Science

3RD EDITION

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Preface xxii STRATEGIES IN CHEMISTRY The features of Guided tour for students xxiv this book 22 Guided tour for students and educators xxvi Chapter summary and key terms 23 Guided tour for educators xxviii Key skills 23 Acknowledgements xxix Key equations 23 About the Australian authors xxx Exercises 23 About the American authors xxxii

chapter 1 chapter 2 Introduction: Matter and , and 28 measurement 2

1.1 The study of chemistry 4 2.1 Atomic theory of matter 30 The atomic and molecular perspective of 2.2 The discovery of atomic structure 31 chemistry 4 Cathode rays and 31 Why study chemistry? 5 Radioactivity 32 1.2 Classifications of matter 5 The nuclear 33 States of matter 5 2.3 The modern view of atomic structure 34 Composition of matter 6 A CLOSER LOOK Basic forces 36 1.3 Properties of matter 8 Atomic numbers, mass numbers and Physical and chemical changes 9 isotopes 36 Separation of mixtures 9 2.4 Atomic mass 37 1.4 Units of measurement 10 The atomic mass scale 37 SI units 10 Average atomic masses 38 A CLOSER LOOK The scientific method 11 A CLOSER LOOK The mass spectrometer 39 Derived SI units 14 2.5 The 39 1.5 Uncertainty in measurement 16 2.6 Molecules and molecular compounds 42 MY WORLD OF CHEMISTRY Molecules and chemical formulae 42 Chemistry in the news 16 Molecular and empirical formulae 42 Precision and accuracy 18 Picturing molecules 43 Significant figures 18 Significant figures in calculations 20 2.7 Ions and ionic compounds 44 STRATEGIES IN CHEMISTRY The importance Predicting ionic charges 45 of practice and estimating answers 21 Ionic compounds 46

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MY WORLD OF CHEMISTRY Elements 3.6 Quantitative information from balanced required by living organisms 48 chemical equations 87

2.8 Naming inorganic compounds 48 3.7 Limiting reactants 90 Names and formulae of ionic compounds 49 Theoretical yields 92 Names and formulae of acids 54 Chapter summary and key terms 94 Names and formulae of binary molecular Key skills 95 compounds 55 Key equations 95 Exercises 96 2.9 Some simple organic compounds 56 56 chapter 4 Some derivatives of alkanes 56 Reactions in aqueous solutions 102 Chapter summary and key terms 58 Key skills 59 Exercises 59

chapter 3 Stoichiometry: Calculations with chemical formulae and equations 66 4.1 General properties of aqueous solutions 104 Electrolytic properties 104 Ionic compounds in water 105 Molecular compounds in water 106 Strong and weak electrolytes 106

4.2 Precipitation reactions 107 3.1 Chemical equations 68 Solubility guidelines for ionic compounds 108 Balancing equations 68 Exchange (metathesis) reactions 109 Indicating the states of reactants and products 70 Ionic equations 110

3.2 Some simple patterns of chemical 4.3 Acids, bases and neutralisation reactivity 71 reactions 112 Combination and decomposition reactions 71 Acids 112 Combustion reactions 74 Bases 112 Strong and weak acids and bases 113 3.3 Formula mass 75 Formula and molecular masses 75 Neutralisation reactions and salts 114 Percentage composition from formulae 76 Neutralisation reactions with gas formation 116 STRATEGIES IN CHEMISTRY Problem solving 76 MY WORLD OF CHEMISTRY Antacids 117 4.4 Oxidation–reduction reactions 118 3.4 Avogadro’s number and the mole 77 Molar mass 78 Oxidation and reduction 118 Oxidation numbers 119 MY WORLD OF CHEMISTRY Glucose monitoring 80 Oxidation of metals by acids and salts 120 Interconverting masses and moles 81 The activity series 122 Interconverting masses and numbers of A CLOSER LOOK The aura of gold 124 particles 82 4.5 Concentrations of solutions 125 3.5 Empirical formulae from analyses 83 Molarity 125 Molecular formulae from empirical formulae 85 Expressing the concentration of an electrolyte 126 Combustion analysis 85 Interconverting molarity, moles and volume 127

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Dilution 128 A CLOSER LOOK The dawning of the MY WORLD OF CHEMISTRY Drinking too nuclear age 166 much water can kill you 128 Nuclear waste 166

4.6 Solution stoichiometry and chemical 5.8 Nuclear power: Fusion 167 analysis 130 5.9 Radiation in the environment and living 131 systems 168 Chapter summary and key terms 135 Radiation doses 169 Key skills 136 Radon 170 Key equations 136 MY WORLD OF CHEMISTRY Radiation therapy 170 Exercises 136 Chapter summary and key terms 172 Key skills 173 chapter 5 Key equations 173 : Changes within Exercises 174 the core of an atom 142 chapter 6 Electronic structure of atoms 178

5.1 Radioactivity 144 Nuclear equations 144 6.1 The wave nature of light 180 Types of radioactive decay 145 6.2 Quantised energy and photons 183 5.2 Patterns of nuclear stability 147 Hot objects and the quantisation of energy 183 -to- ratio 147 The photoelectric effect and photons 184 Radioactive series 149 Further observations 149 6.3 Line spectra and the Bohr model 185 Line spectra 186 5.3 Nuclear transmutations 151 Bohr’s model 187 Accelerating charged particles 151 The energy states of the hydrogen atom 187 Reactions involving 152 Limitations of the Bohr model 189 Transuranium elements 152 6.4 The wave behaviour of matter 189 5.4 Rates of radioactive decay 152 MY WORLD OF CHEMISTRY Australian Radiometric dating 154 Synchrotron 191 Calculations based on half-life 155 The uncertainty principle 191 5.5 Detection of radioactivity 157 6.5 and atomic orbitals 192 Radiotracers 159 Orbitals and quantum numbers 194 5.6 Energy changes in nuclear reactions 159 6.6 Representations of orbitals 196 MY WORLD OF CHEMISTRY Medical The s orbitals 196 applications of radiotracers 160 The p orbitals 198 Nuclear binding energies 162 The d and f orbitals 199 5.7 Nuclear power: Fission 163 A CLOSER LOOK Probability density and radial Nuclear reactors 164 probability functions 200

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6.7 Many- atoms 200 Chapter summary and key terms 243 Orbitals and their energies 200 Key skills 244 Key equation 244 Electron spin and the Pauli exclusion principle 201 Exercises 244

6.8 Electron configurations 202 chapter 8 Hund’s rule 203 Basic concepts of chemical Electron configurations 205 bonding 250 Transition metals 206 The lanthanides and actinides 206

6.9 Electron configurations and the periodic table 207 Anomalous electron configurations 210 Chapter summary and key terms 212 Key skills 213 8.1 Chemical bonds, Lewis symbols and Key equations 213 the octet rule 252 Exercises 213 Lewis symbols 252 The octet rule 252 chapter 7 8.2 Ionic bonding 253 Periodic properties of the elements 220 Energetics 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 258 Lewis structures 258 Multiple bonds 260 7.1 Development of the periodic table 222 8.4 Bond polarity and electronegativity 260 7.2 Effective nuclear charge 223 Electronegativity 261 A CLOSER LOOK Effective nuclear charge 225 Electronegativity and bond polarity 262 7.3 Sizes of atoms and ions 225 Dipole moments 263 Periodic trends in atomic radii 227 Differentiating ionic and covalent bonding 265 Periodic trends in ionic radii 228 8.5 Drawing Lewis structures 267 7.4 Ionisation energy 230 Formal charge 269 Variations in successive ionisation energies 231 A CLOSER LOOK Oxidation numbers, formal Periodic trends in first ionisation energies 232 charges and actual partial charges 272

Electron configurations of ions 234 8.6 Resonance structures 272

7.5 Electron affinities 235 8.7 Exceptions to the octet rule 274

7.6 Metals, non-metals and metalloids 236 Odd number of electrons 275 Metals 237 Less than an octet of valence electrons 275 MY WORLD OF CHEMISTRY movement More than an octet of valence electrons 276 powers electronics 238 8.8 Strengths of covalent bonds 277 Non-metals 241 Bond enthalpies and the enthalpies of Metalloids 242 reactions 278

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MY WORLD OF CHEMISTRY Explosives and Chapter summary and key terms 328 Alfred Nobel 281 Key skills 329 Bond enthalpy and bond length 282 Key equations 329 Exercises 329 Chapter summary and key terms 284 Key skills 284 Key equations 285 chapter 10 Exercises 285 Intermolecular forces: Gases 336

chapter 9 Molecular geometry and bonding theories 292

10.1 Characteristics of gases 338

10.2 Pressure and its measurement 338 MY WORLD OF CHEMISTRY Blood pressure 340 9.1 Molecular shapes 294 10.3 The gas laws 341 9.2 The VSEPR model 296 The pressure–volume relationship: Boyle’s law 341 The effect of non-bonding electrons and The temperature–volume relationship: multiple bonds on bond angles 300 Charles’s law 342 Molecules with expanded valence shells 301 The quantity–volume relationship: Shapes of larger molecules 304 Avogadro’s law 342

9.3 Molecular shape and molecular polarity 305 10.4 The ideal-gas equation 344 9.4 Covalent bonding and orbital overlap 307 Relating the ideal-gas equation and the gas laws 346 9.5 Hybrid orbitals 309 sp hybrid orbitals 309 10.5 Further applications of the ideal-gas equation 348 sp2 and sp3 hybrid orbitals 311 Gas densities and molar mass 348 Hybridisation involving d orbitals 312 Volumes of gases in chemical reactions 350 Hybrid orbital summary 312 10.6 Gas mixtures and partial pressures 351 9.6 Multiple bonds 314 Partial pressures and mole fractions 352 General conclusions 315 Collecting gases over water 353 9.7 Molecular orbitals 315 10.7 Kinetic-molecular theory 355 The hydrogen 316 Distribution of molecular speed 356 Bond order 317 Application of kinetic-molecular theory to the 9.8 Second-period diatomic molecules 318 gas laws 357

Molecular orbitals for Li2 and Be2 319 A CLOSER LOOK The ideal-gas equation 357 Molecular orbitals from 2p atomic orbitals 319 10.8 Molecular effusion and diffusion 358 Electron configurations for B to Ne 321 2 2 Graham’s law of effusion 359 A CLOSER LOOK Phases in atomic and Diffusion and mean free path 361 molecular orbitals 322 MY WORLD OF CHEMISTRY Gas separations 362 Electron configurations and molecular properties 323 10.9 Real gases: Deviations from ideal Heteronuclear diatomic molecules 326 behaviour 362

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The van der Waals equation 364 Types of liquid crystals 401 MY WORLD OF CHEMISTRY Gas pipelines 367 MY WORLD OF CHEMISTRY Liquid crystal Chapter summary and key terms 367 displays 404

Key skills 368 11.8 Structures of solids 405 Key equations 368 Unit cells 405 Exercises 369 The crystal structure of sodium chloride 407 Close packing of spheres 409 chapter 11 11.9 Bonding in solids 411 Intermolecular forces: Liquids Molecular solids 411 and solids 376 A CLOSER LOOK X-ray diffraction by crystals 412 Covalent-network solids 413 Ionic solids 414 Metallic solids 414 Chapter summary and key terms 415 Key skills 416 Key equations 417 Exercises 417 11.1 A molecular comparison of gases, liquids and solids 378 chapter 12 11.2 Intermolecular forces 380 Properties of solutions 426 Dispersion 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 389 12.1 The solution process 428 Viscosity 389 Energy changes and solution formation 429 Surface tension 390 Solution formation, spontaneity and disorder 430 Solution formation and chemical reactions 431 11.4 Phase changes 391 Energy changes accompanying phase A CLOSER LOOK Hydrates 432 changes 391 12.2 Saturated solutions and solubility 432 Heating curves 393 12.3 Factors affecting solubility 434 Critical temperature and pressure 394 Solute–solvent interactions 434 11.5 Vapour pressure 395 MY WORLD OF CHEMISTRY Fat-soluble and Explaining vapour pressure at the molecular water-soluble vitamins 437 level 396 Pressure effects 437 Volatility, vapour pressure and temperature 396 MY WORLD OF CHEMISTRY Blood gases and Vapour pressure and boiling point 397 deep-sea diving 439 A CLOSER LOOK The Clausius–Clapeyron Temperature effects 439 equation 398 12.4 Ways of expressing concentration 440 11.6 Phase diagrams 398 Mass percentage, ppm and ppb 441 The phase diagrams of H O and CO 399 2 2 Mole fraction, molarity and molality 442 11.7 Liquid crystals 401 Conversion of concentration units 443

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12.5 Colligative properties 445 Water purification: Desalination 486 Lowering the vapour pressure 445 Water purification: Municipal treatment 487 Boiling-point elevation 447 A CLOSER LOOK Water softening 488 A CLOSER LOOK Ideal solutions with two or The challenges of water purification 488 more volatile components 448 13.5 490 Freezing-point depression 449 Osmosis 451 Chapter summary and key terms 493 Key skills 493 Determination of molar mass 454 Exercises 494 12.6 Colloids 455 Hydrophilic and hydrophobic colloids 456 chapter 14 Removal of colloidal particles 458 500 Chapter summary and key terms 460 Key skills 461 Key equations 461 Exercises 462

chapter 13 468

14.1 The nature of energy 502 Kinetic 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 505 13.1 Earth’s atmosphere 470 Internal energy 506 Composition of the atmosphere 470 Relating DU to heat and work 507 Photochemical reactions in the atmosphere 471 Endothermic and exothermic processes 508 Photoionisation 473 State functions 509 Ozone in the stratosphere 474 14.3 Enthalpy 510 13.2 Human activities and Earth’s atmosphere 475 14.4 Enthalpies of reaction 513 The ozone layer and its depletion 475 A CLOSER LOOK Using enthalpy as a guide 515 The troposphere 477 Sulfur compounds and acid rain 477 14.5 516 Nitrogen oxides and photochemical smog 479 Heat capacity and specific heat capacity 516 Greenhouse gases: Water vapour, carbon Constant-pressure calorimetry 517 dioxide and climate 480 Bomb calorimetry (constant-volume MY WORLD OF CHEMISTRY Methane as a calorimetry) 519 greenhouse gas 482 14.6 Hess’s law 520

13.3 Earth’s water 482 14.7 Enthalpies of formation 523 The global water cycle 483 Using enthalpies of formation to calculate Salt water: Earth’s oceans and seas 483 enthalpies of reaction 524 Freshwater and groundwater 484 14.8 Spontaneous processes 527 13.4 Human activities and Earth’s water 485 Seeking a criterion for spontaneity 529 Dissolved oxygen and water quality 485 Reversible and irreversible processes 529

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14.9 Entropy and the second law of 15.4 The change of concentration with time thermodynamics 531 (integrated rate equations) 578 Entropy change 532 Zero-order reactions 578 DS for phase changes 532 First-order reactions 578 A CLOSER LOOK The entropy change when a Second-order reactions 580 gas expands isothermally 533 Half-life 582 The second law of thermodynamics 534 MY WORLD OF CHEMISTRY Bromomethane in the atmosphere 582 14.10 Molecular interpretation of entropy 535 Expansion of a gas at the molecular level 535 15.5 Temperature and rate 584 Boltzmann’s equation and microstates 536 The collision model 585 Molecular motions and energy 537 The orientation factor 585 Making qualitative predictions about DS 538 Activation energy 586 The third law of thermodynamics 541 The Arrhenius equation 587 Determining the activation energy 588 14.11 Entropy changes in chemical reactions 542 Entropy changes in the surroundings 544 15.6 Reaction mechanisms 590 Elementary reactions 590 14.12 Gibbs free energy (Gibbs energy) 545 Multistep mechanisms 591 Standard free energy changes 546 Rate laws for elementary reactions 592 14.13 Gibbs energy and temperature 548 The rate-determining step for a multistep MY WORLD OF CHEMISTRY Driving mechanism 594 non-spontaneous reactions 551 Mechanisms with a slow initial step 595 Chapter summary and key terms 552 Mechanisms with a fast initial step 596 Key skills 553 15.7 598 Key equations 554 Exercises 554 Homogeneous catalysis 598 Heterogeneous catalysis 600 chapter 15 MY WORLD OF CHEMISTRY Catalytic 564 converters 601 Chapter summary and key terms 603 Key skills 604 Key equations 604 Exercises 605

chapter 16 Chemical equilibrium 614

15.1 Factors that affect reaction rates 566

15.2 Reaction rates 567 Change 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 16.1 The concept of equilibrium 616 Reaction orders: Exponents in the rate law 573 16.2 The equilibrium constant 618 Units of rate constants 575 MY WORLD OF CHEMISTRY The Haber Using initial rates to determine rate laws 576 process 619

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Evaluating Kc 620 Proton-transfer reactions 657 Equilibrium constants in terms of pressure, Conjugate acid–base pairs 658 KP 621 Relative strengths of acids and bases 660 Equilibrium constants and units 623 17.3 The autoionisation of water 662 16.3 Interpreting and working with The ion product of water 662 equilibrium constants 623 The magnitude of equilibrium constants 623 17.4 The pH scale 664 The direction of the chemical equation pOH and other ‘p’ scales 665 and K 625 Measuring pH 667 Relating chemical equation stoichiometry and equilibrium constants 625 17.5 Strong acids and bases 668 Strong acids 668 16.4 Heterogeneous equilibria 627 Strong bases 669 16.5 Calculating equilibrium constants 629 17.6 Weak acids 670

16.6 Applications of equilibrium constants 631 Calculating Ka from pH 671 Predicting the direction of reaction 631 Percent ionisation 673 Calculating equilibrium concentrations 633 Using Ka to calculate pH 673 16.7 The equilibrium constant and free Polyprotic acids 678 energy 635 17.7 Weak bases 680 16.8 Le Châtelier’s principle 638 Types of weak bases 680 Change in reactant or product concentration 638 17.8 Relationship between Ka and Kb 683 Effects of volume and pressure changes 641 MY WORLD OF CHEMISTRY Amines and Effect of temperature changes 642 amine hydrochlorides 685 The effect of catalysts 644 A CLOSER LOOK Controlling nitric oxide 17.9 Acid–base properties of salt solutions 685 emissions 646 An anion’s ability to react with water 686 Chapter summary and key terms 647 A cation’s ability to react with water 686 Key skills 648 Combined effect of cation and anion in Key equations 648 solution 688 Exercises 648 17.10 Acid–base behaviour and chemical chapter 17 structure 689 Acid–base equilibria 654 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 17.1 Acids and bases: A brief review 656 Key skills 698 17.2 Brønsted–Lowry acids and bases 656 Key equations 699 The H1 ion in water 656 Exercises 699

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chapter 18 chapter 19 Additional aspects of aqueous 752 equilibria 706

19.1 Oxidation states and oxidation–reduction 18.1 The common-ion effect 708 equations 754

18.2 Buffer solutions 711 19.2 Balancing redox equations 756 Composition and action of buffer solutions 711 Half-reactions 756 Calculating the pH of a buffer 712 Balancing equations by the method of Buffer capacity and pH range 714 half-reactions 756 Addition of strong acids or bases to buffers 715 Balancing equations for reactions occurring in basic solution 759 MY WORLD OF CHEMISTRY Blood as a buffer solution 716 19.3 Voltaic cells 761

18.3 Acid–base titrations 717 19.4 Cell potentials under standard Strong acid–strong base titrations 717 conditions 764 Weak acid–strong base titrations 719 Standard reduction (half-cell) potentials 766 Titrations of polyprotic acids 723 Strengths of oxidising and reducing agents 771 Titrating with an acid–base indicator 724 19.5 Free energy and redox reactions 772 18.4 Solubility equilibria 725 Emf, free energy and the equilibrium constant 774 The solubility-product constant, Ksp 726 A CLOSER LOOK Electrical work 776

Solubility and Ksp 727 19.6 Cell potentials under non-standard A CLOSER LOOK Limitations of solubility conditions 776 products 729 The Nernst equation 777 18.5 Factors that affect solubility 730 Concentration cells 779 Common-ion effect 730 MY WORLD OF CHEMISTRY Heartbeats and Solubility and pH 731 electrocardiography 780 MY WORLD OF CHEMISTRY Ocean 19.7 Batteries and fuel cells 782 acidification 732 Lead-acid battery 783 Formation of complex ions 734 Alkaline battery 783 MY WORLD OF CHEMISTRY Tooth decay and fluoridation 736 Nickel-cadmium, nickel-metal hydride and lithium-ion batteries 784 Amphoterism 737 Hydrogen fuel cells 784 18.6 Precipitation and separation of ions 738 Direct methanol fuel cells 785 Selective precipitation of ions 738 19.8 Corrosion 785 18.7 Qualitative analysis for metallic elements 740 Corrosion of iron (rusting) 786 Chapter summary and key terms 743 Preventing the corrosion of iron 787 Key skills 744 Key equation 744 19.9 Electrolysis 788 Exercises 745 Quantitative aspects of electrolysis 789

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Chapter summary and key terms 792 Occurrence and preparation of S, Se Key skills 793 and Te 822 Key equations 793 Properties and uses of sulfur, selenium Exercises 793 and tellurium 822 Sulfides 822 chapter 20 Oxides, oxyacids and oxyanions of sulfur 823 Chemistry of the non-metals 802 20.7 Nitrogen 825 Properties 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 20.1 Periodic trends and chemical MY WORLD OF CHEMISTRY Nitroglycerin and reactions 804 heart disease 829 Chemical reactions 805 20.8 The other group 15 elements: P, As, 20.2 Hydrogen 806 Sb and Bi 830 Isotopes of hydrogen 807 General characteristics of the group 15 Properties of hydrogen 807 elements 830 Preparation of hydrogen 808 Occurrence, isolation and properties of phosphorus 831 Uses of hydrogen 808 Phosphorus halides 831 A CLOSER LOOK The hydrogen economy 809 Oxy compounds of phosphorus 831 Binary hydrogen compounds 809 20.9 Carbon 833 20.3 Group 18: The noble gases 811 Elemental forms of carbon 833 Noble gas compounds 811 Oxides of carbon 834 20.4 Group 17: The halogens 812 MY WORLD OF CHEMISTRY Carbon fibres Properties and preparation of the halogens 813 and composites 834 Uses of the halogens 814 Carbonic acid and carbonates 835 The hydrogen halides 815 Carbides 836 Interhalogen compounds 816 Other inorganic compounds of carbon 837 Oxyacids and oxyanions 816 20.10 The other group 14 elements: Si, Ge, 20.5 Oxygen 817 Sn and Pb 837 Properties of oxygen 817 General characteristics of the group 14 Preparation of oxygen 817 elements 837 Uses of oxygen 818 Occurrence and preparation of silicon 838 Ozone 818 Silicates 838 Oxides 819 Glass 840 Peroxides and superoxides 820 Silicones 840

20.6 The other group 16 elements: S, Se, Te 20.11 Boron 841 and Po 821 Chapter summary and key terms 843 General characteristics of the group 16 Key skills 844 elements 821 Exercises 844

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chapter 21 chapter 22 Chemistry of the transition metals 850 The chemistry of organic compounds 890

21.1 Transition metals 852 Physical properties 852 22.1 General characteristics of organic Electron configurations and oxidation states 853 molecules 892 Magnetism 854 The structure of organic molecules 892 The stabilities of organic molecules 892 21.2 Transition metal complexes 856 The development of coordination chemistry: 22.2 An introduction to hydrocarbons 893 Werner’s theory 856 Alkanes 894 The metal–ligand bond 858 22.3 Applications and physical properties of Charges, coordination numbers and geometries 859 alkanes 895 Homologous series 895 21.3 Ligands with more than one donor atom 861 22.4 Structures of alkanes 896 Metals and chelates in living systems 863 MY WORLD OF CHEMISTRY Petroleum products 897 21.4 Nomenclature and isomerism in coordination chemistry 865 Hybridisation 898 shape and conformations 899 A CLOSER LOOK Entropy and the chelate effect 866 Constitutional structural isomers 902

Isomerism 868 22.5 Alkane nomenclature 903 Structural isomerism 868 Stereoisomerism 869 22.6 Cycloalkanes 906 A CLOSER LOOK Carbon nanotubes 908 21.5 Colour and magnetism in coordination chemistry 872 22.7 Organic functional groups 909 Colour 872 MY WORLD OF CHEMISTRY Structure–activity Magnetism of coordination compounds 874 relationships 911

21.6 Crystal-field theory 874 22.8 Reactions of alkanes 911 MY WORLD OF CHEMISTRY The battle for Combustion 911 iron in living systems 875 Classification of C and H 913 Electron configurations in octahedral Free-radical reactions and electron movement 913 complexes 879 A CLOSER LOOK Reactivity by carbon Tetrahedral and square planar complexes 880 classification 915 A CLOSER LOOK Charge-transfer colour 882 Chapter summary and key terms 917 Chapter summary and key terms 883 Key skills 917 Key skills 884 Key equations 918 Exercises 885 Exercises 918

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chapter 23 24.3 Arrow notation and resonance structures: Electron counting 963 of organic compounds 926 MY WORLD OF CHEMISTRY The chemistry of vision 964 A CLOSER LOOK Describing charge 965

24.4 Electrophilic addition reactions 966 Addition reactions involving HX (X = Cl, Br, I) 967

Addition reactions involving H2O 970

Halogenation: Addition of Br2 and Cl2 972 Halohydrin formation 973 23.1 Stereochemistry in 928 A CLOSER LOOK Stereochemistry in 23.2 Cis–trans isomerism in cycloalkanes 929 halohydrin formation 977

23.3 Chirality in organic compounds 931 24.5 Alkanes from : Catalytic hydrogenation 977 23.4 Measuring optical activity 933 A CLOSER LOOK Hydrogenation 978 23.5 Absolute stereochemistry 936 24.6 Addition polymerisation 980 Using priority rules to find a stereocentre’s absolute configuration 936 Making polymers 981 Structure and physical properties of addition MY WORLD OF CHEMISTRY Chiral drugs 938 polymers 982 23.6 Molecules with more than one MY WORLD OF CHEMISTRY Recycling stereocentre 940 plastics 984 Resolution: Separating enantiomers 942 MY WORLD OF CHEMISTRY The accidental Chapter summary and key terms 944 discovery of Teflon® 985 Key skills 944 MY WORLD OF CHEMISTRY Vulcanisation 986 Key equations 944 Chapter summary and key terms 987 Exercises 945 Key skills 988 chapter 24 Key equations 988 Exercises 988 Chemistry of alkenes and 952 chapter 25 Alcohols, haloalkanes and ethers 994

24.1 The structure of unsaturated hydrocarbons 954 The �-bond 954 25.1 Alcohols: Structure, properties and Bonding in alkenes 955 nomenclature 996 Bonding in alkynes 957 MY WORLD OF CHEMISTRY Vitamin D 998 MY WORLD OF CHEMISTRY Terpenes and Common alcohols 999 isoprene 959 MY WORLD OF CHEMISTRY The solubility 24.2 Isomerism and nomenclature 960 nexus 1000 Isomerism in alkenes—The E, Z system 961 Naming alcohols 1001 Alkynes 963 Classifying alcohols 1003

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25.2 Haloalkanes 1004 Reduction reactions 1048

25.3 Ethers: Structure, properties and Cyanohydrins 1049 nomenclature 1006 Tautomerism in aldehydes and ketones 1051 Naming ethers 1007 Halogenation of aldehydes and ketones 1053

A CLOSER LOOK Crown ethers 1008 26.4 Carbohydrates 1054

25.4 Reactions of alcohols 1009 Monosaccharides 1054 Alkoxides 1009 Cyclic versus open-chain structures 1057 Basicity of alcohols 1010 MY WORLD OF CHEMISTRY Glucosamine 1058 Alcohols to haloalkanes 1010 Oligosaccharides and polysaccharides 1060 Dehydration of alcohols 1011 MY WORLD OF CHEMISTRY Cyclodextrins 1062 MY WORLD OF CHEMISTRY Vitamin C 1065 25.5 Nucleophilic substitution reactions of haloalkanes 1011 Chapter summary and key terms 1067 Key skills 1067 A CLOSER LOOK Molecularity 1014 Key equations 1067 25.6 Haloalkanes to alkenes: b-elimination 1015 Exercises 1068

25.7 Substitution versus elimination 1018 chapter 27 A CLOSER LOOK Nucleophile or Lewis base? 1019 Carboxylic acids and their E1 and SN1 reactions 1020 derivatives 1076 MY WORLD OF CHEMISTRY Polymerisation versus macrocyclisation 1023 Chapter summary and key terms 1024 Key skills 1025 Key equations 1025 Exercises 1025

chapter 26 27.1 Carboxylic acids 1078 Aldehydes, ketones and Structure, properties and nomenclature 1078 carbohydrates 1034 Acidity 1081

27.2 Preparation of carboxylic acids 1084

27.3 Esters and esterification 1086

27.4 Fats, oils and waxes 1090 Soaps and detergents 1093

27.5 Acid chlorides, anhydrides and 26.1 Aldehydes, ketones and the carbonyl nucleophilic acyl substitution 1095 group 1036 MY WORLD OF CHEMISTRY Steroids 1096 Nucleophilic acyl substitution 1098 26.2 Preparation of aldehydes and ketones 1039 Oxidation of 1° and 2° alcohols 1040 27.6 Condensation polymerisation 1100 Ozonolysis 1041 MY WORLD OF CHEMISTRY Bindeez 1101

26.3 Reactions of aldehydes and ketones 1042 MY WORLD OF CHEMISTRY Towards the Addition of carbon nucleophiles—Grignard plastic car 1103 reactions 1042 Polymers for 1104 Addition of nitrogen and oxygen nucleophiles: MY WORLD OF CHEMISTRY Biodegradable Formation of imines and acetals 1045 sutures 1105

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Chapter summary and key terms 1107 Reactivity of amines 1154 Key skills 1107 Synthesis of amines 1157 Key equations 1107 Amides 1159 Exercises 1108 29.2 Amino acids 1161 chapter 28 Acid–base properties 1165 Benzene and its derivatives 1114 A CLOSER LOOK Sickle-cell anaemia 1166 Reactions involving amino acids 1170

29.3 Proteins, peptides and enzymes 1172 Coding peptides 1172 Protein structure 1175 Enzymes 1177 Sequencing of peptides and proteins 1179 28.1 The structure of benzene 1116 MY WORLD OF CHEMISTRY B group Bonding in benzene 1116 vitamins 1181

28.2 Isomerism and nomenclature in 29.4 Nucleic acids and DNA 1182 aromatic compounds 1117 Chapter summary and key terms 1189 MY WORLD OF CHEMISTRY The discovery Key skills 1190 of liquid crystals 1119 Key equations 1190 Phenols 1121 Exercises 1190

28.3 Resonance and aromaticity 1122 chapter 30 Aromaticity 1123 Solving molecular structure 1198 28.4 Acidity of alcohols and phenols 1124

28.5 Electrophilic aromatic substitution (EAS) reactions 1127 Directing groups and substitution effects 1129 A CLOSER LOOK Organic dyes 1130 Chapter summary and key terms 1138 Key skills 1139 30.1 The electromagnetic spectrum 1200 Key equations 1139 A CLOSER LOOK Using spectroscopic Exercises 1139 methods to measure reaction rates 1202 chapter 29 30.2 Infrared (IR) 1202 Nitrogen-containing organic The spring model 1203 compounds 1146 Measuring IR spectra 1204 MY WORLD OF CHEMISTRY IR spectroscopy for biological imaging 1209

30.3 Nuclear magnetic resonance (NMR) spectroscopy 1210 Nuclear magnetic resonance frequencies 1212 MY WORLD OF CHEMISTRY Nuclear spin 29.1 Amines and the amide bond 1148 and magnetic resonance imaging 1213 Amines 1148 The chemical shift 1214 MY WORLD OF CHEMISTRY Amines and Sample preparation 1215 amine hydrochlorides 1152 Interpreting NMR spectra 1216

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Integration 1220 Appendices Spin–spin coupling 1221 A Mathematical operations 1252 13C NMR spectra 1224 B Properties of water 1258 C 30.4 1226 Thermodynamic quantities for selected substances at 298.15 K (25 °C) 1259 Electron impact ionisation mass spectrometry 1226 Interpreting mass spectra 1228 D Aqueous equilibrium constants 1262 E Standard reduction potentials at 25 °C 1264 30.5 Compound identification using spectra 1232 Deducing the molecular formula of an organic Answers to Concept Checks 1265 compound 1232 Chemical wet testing: Tests for functional Answers to Figure it Out 1274 groups 1234 Chapter summary and key terms 1237 Glossary 1280 Key skills 1238 Index 1296 Key equations 1238 Exercises 1239

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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 . 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 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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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 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 Chemistry Monash University, Clayton VIC 3800 [email protected] s Dalius Sagatys Science and Faculty Queensland University of Technology, Brisbane QLD 4001 [email protected] s Adrian George School of Chemistry University of Sydney, NSW 2006 [email protected]

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MAKING CONNECTIONS The 3rd edition of Chemistry: The Central Science includes several Project2_Layout 1 4/06/13 2:26 PM Page 1 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

• Review this on page xx 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 GLUCOSE MONITORING glucoseMy World concentration of Chemistry after eating. However, in a diabetic person, either little or no insulin is produced (Type 1 diabetes) Over 1 million Australians (although estimates or insulin is produced but the cells cannot take it up properly vary) have diabetes, and globally the number ap- (TypeChemistry 2 diabetes). occurs The result allis that around the blood us, glucose throughout concen- every day. Recognising the proaches 172 million. Diabetes is a metabolic trationimportance is too high. Peopleof chemistry normally have in ayour range dailyof 70–120 life mg can improve your understanding disorder in which the body either cannot pro- glucose per litre of blood. A person who has not eaten for 8 duce or cannot properly use the hormone hoursof chemical or more is diagnosedconcepts. as di abeticMy World if his or herof Chemistry glucose showcases chemistry’s insulin. One signal that a person is diabetic level is 1260 mg dm-3 or higher. is that the concentration of glucose in the blood is higher than connectionGlucose meters to work world by the events, introduction scientific of blood from discoveries, a and medical normal. Therefore, people who are diabetic need to measure person, usually by a prick of the finger, onto a small strip of their blood glucose concentrations regularly. Untreated dia- paperbreakthroughs that contains chemicals throughout that react the with text. glucose. Inser- betes can cause severe complications such as blindness and tion of the strip into a small battery-operated reader gives the loss of limbs. glucose concentration. The mechanism of the readout varies The body converts most of the food we eat into glucose. from one monitor to another—it may be a measurement of a After digestion, glucose is delivered to cells via the blood. smallMaking electrical connections current or measurement visually of light produced in a Cells need glucose to live, and insulin must be present in order . Depending on the reading on any given for glucose to enter the cells. Normally, the body adjusts the day, a diabetic person may need to receive an injection of concentration of insulin a utomatically, in concert with the insulinMicro or simplyto Macro stop eating Art sweets for a while. These illustrations offer three parts: a macroscopic image (what you can see with your eyes); a molecular image (what the molecules are doing); ؊ H ؉ ؊ H + and a symbolic representation (how represent the process with

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.(؊ symbols and equations ϩ Ϫ H ϩ + &O 0J 0J V LVR[LGLVHG + DT LVUHGXFHG Project2_Layout 1 4/03/13 2:31 PM Page 1 ϩ ORVHVHOHFWURQV JDLQVHOHFWURQV 0J 5HDFWDQWV 3URGXFWV ϩ ϩ +&O DT  0J V + J  0J&O DT A new intermediate step has been added, showing where chemistry 2[LGDWLRQ ϩ Ϫ  ϩ Ϫ QXPEHU occurs in the problem-solving process.

FIGURE IT OUT Which species is reduced in this reaction? Which species is the reducing agent? *NEW* Figure It Out questions and Voice Balloons Ϫ MnO4 (aq) Figure It Out questions encourage you to stop and analyse the artwork in the text, for conceptual understanding. ‘Voice Balloons’ in selected Ϫ The purple colour of MnO4 disappears immediately as figures help you break down and understand the components of the 2Ϫ reaction with C2O4 occurs image. At end point, purple colour of Ϫ MnO4 remains because all 2Ϫ C2O4 consumed

2Ϫ C2O4 (aq) « FIGURE 19.2 of an acidic (a) (b) solution of Na2C2O4 with KMnO4(aq).

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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 the chemical form of a substance exactly when we use the mole concept. Suppose you read that 1 mol of nitrogen is produced in a particular reaction. You might interpret 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 avoid ambiguity, it is important to state explicitly the chemical form being discussed. guided tour for students xxv Using the chemical formula N2 avoids ambiguity.

SAMPLE EXERCISE 3.9 Calculating molar massMaking connections to problem-solving and critical thinking skills What is the molar mass of glucose, C6H12O6? SOLUTION Analyse/Plan/Solve/Check Analyse We are given a molecular formula which gives us the types of atoms and their number in the molecule. This four-step problem-solving method helps you understand what you are Plan The molar mass of any substance is numerically equal to its formula mass which will have units of u, whereas the molar mass willbeing have askedunits of gto mol solve,-1. We to plan how you will solve each problem, to work your way proceed as in Sample Exercise 3.5. Solve Our first step is to determine the formula mass throughof glucose. the solution, and to check your answers. This method is introduced in 6 C atoms = 6(12.0 u) = 72.0Chapter u 3 and reinforced throughout the book. 12 H atoms = 12(1.0 u) = 12.0 u 6 O atoms = 6(16.0 u) = 96.0 u 180.0 u Because glucose has a formula mass of 180.0 u, one mole of this substance has a mass *Brown 3e - ch04 (India).QXD_BLB02_038-075hr2 5/03/13 10:20 AM Page 126 -1 of 180.0 g. In other words, C6H12O6 has a molar mass of 180.0 g mol . Check The magnitude of our answer seems reasonable, and g mol-1 is the appropri- ate unit for the molar mass. *Brown 3e - ch03 (India).QXD_BLB03_038-075 5/03/13 10:25 AM Page 76 126CommentCHAPTERGlucose 4 Reactionsis sometimes in Aqueous called dextrose. Solution Also known as blood sugar, glu- cose is found widely in nature, occurring, for example, in honey and fruits. Other types of sugars used as food are converted into glucose in the stomach or liver before theySAMPLE are used EXERCISE by the body 4.9 as energyCalculating sources. Because molarity glucose requires no conversion, it76 is often givenCHAPTER intravenously 3 Stoichiometry: to patients Calculations who need withimmediateDual-Column Chemical nourishme Formulaent. Problem-Solving and Equations Strategies Calculate the molarity of a solution made by dissolving 23.4 g of sodium sulfate (Na2SO4) in enough PRACTICEwater to form 125EXERCISE cm3 of solution. Found in Selected Sample Exercises, these strategies explain the thought Calculate the molar mass of Ca(NO3)2. (b) If a chemical formula has parenthe- 1 Ca atom = 1(40.1 u) = 40.1 u -1 process involved in each step of a mathematical calculation using a unique Answer:SOLUTION164.1 g mol ses, the subscript outside the paren- 2 N atoms = 2(14.0 u) = 28.0 u theses is a multiplier for all atoms (SeeAnalyse also ExerciseWe are 3.27.) given the number of grams of layout solute forPlan clarity.We can They calculate help6 molarityO atoms you using= develop6(16.0 Equa u) tion= a96.0 4 .33.conceptual u To do so, understanding of those inside. Thus for Ca(NO3)2, we have (23.4 g), its chemical formula (Na2SO4) and the volume of we must convert the grams of solute to moles and the volume the solution (125 cm3) and asked to calculate the molaritycalculations. of of the solution from millilitres to litres. 164.1 u the solution. MY WORLD OF CHEMISTRY PRACTICE EXERCISE Solve The number of moles of Na2SO4 is Calculate the formula mass of (a) Al(OH) and (b) CH OH. 23.43 g 3 GLUCOSE MONITORING obtained by dividing its glucosemass by its concentration molar mass: Answers: after eating.(a) 78.0 However, u, Moles(b) 32.0 inNa u aSO diabetic 0.165 mol 2 4 = -1 = person, either little or no(See insulin also Exercises is produced 3.17, (Type 3.18.) 1 diabetes)142 g mol Over 1 million Australians (although estimates or insulin is produced but the cells cannot take it up properly vary) have diabetes, and globally the number ap- (Type 2 diabetes). The result is that the blood glucose concen-125 Converting the volume of the solution to litres: Litres solution dm3 0.125 dm3 proaches 172 million. Diabetes is a metabolic tration is too high. People normally have a range of 70–120= mg1000 = 3 disorder in which the body either cannot pro- glucose per decilitre (ddm ) of blood. A person who has nota b duce or cannot properly use the hormone eaten for 8 hours or morePercentage is diagnosed asComposition diabetic if his or herfrom Formulae -3 0.165 mol mol insulin. One signal thatThus a person the molarity is diabet- is glucose level is 126 mg ddm or higher. M Molarity = 3 = 1.32 3 = 1.32 ic is that the concentration of glucose in the blood is higher Glucose meters workOccasionally by the introduction we must ofcalculate blood0.125 from the dm apercentagedm composition of a compound (that than normal. Therefore, people who are diabetic need to person, usually by a is,prick the of percentage the finger, ontoby mass a small contributed strip of by each element in the substance). For measure their blood glucose concentrations regularly. Un- paper that contains chemicalsexample, thatin order react towith verify glucose. the purity Inser- of a compound, we may wish to compare PRACTICE EXERCISE treated diabetes can cause severe complications such as blind- tion of the strip into athe small calculated battery-operated percentage reader composition gives the of the substance with that found experi- ness and loss of limbs. Calculate the molarity ofgl a ucosesolution concentration. made by dissolvingmentally. The mechanism 5.00Calculating g of glucoseof the percentage readout (C6H12 Ovaries6 )composition in sufficient water is a straightforward to matter if the form exactly 100 cm3 of solution. The body converts most of the food we eat into glucose. from one monitor to chemicalanother—itStrategies formula may be isa known.measurement in Chemistry of a After digestion, glucose is delivered to cellsAnswer: via 0.278 the blood. M small electrical current or measurement of light produced in a Cells need glucose to live, and insulin must be present in chemical reaction. Depending on the reading onnumber any given of atoms atomic mass (See slso Exercises 4.45, 4.46.) Strategies in Chemistry teach * ways to analyse information and organise thoughts, order for glucose to enter the cells. Normally, the body adjusts day, a diabetic person may need to receive an of injection that element of of the element % Element 100% [3.10] th e concentration of insulin automatically, in concert with the insulin or simply stop eating sweetshelping for a towhile. improve= formula your mass problem-solvingof the compound * and critical-thinking abilities.

STRATEGIES IN CHEMISTRYExpressing the Concentration of an Electrolyte When an ionic compound dissolves the relative concentrations of the ions PROBLEM SOLVING learnt earlier. Recognise that some data may not be given explic- introduced into the solutionitly depend in the problem; on the youchemical may be formula expected ofto theknow compound. certain quanti- + - Practice is the key to successFor in example,solving problems. a 1.0 M solutionties (suchof NaCl as Avogadro’s is 1.0 M in number) Na ions or lookand them1.0 M upin in Cl tablesions. (such + 2- As you practise, you can improveSimilarly, your a 1.0 skills M solution by ofas Naatomic2SO 4masses).is 2.0 M Recognisein Na ions also and that 1.0 your M inplan SO may4 ions. involve following these steps. Thus, the concentration ofeither an a electrolyte single step or solution a series of can steps b ewith specified intermediate either answers. in terms of the compound usedStep to 3: make Solve the the solution problem. (1.0Use M Nathe 2knownSO4) or information in terms of and Step 1: Analyse the problem. Read the + 2- problem carefully. Whatthe isions it askingthat the you solution to containssuitable equations(2.0 M Na or andrelationships 1.0 M SO t4o solve). for the unknown. do? What information does it provide you with? List both the Be careful with significant figures, signs and units. data you are given and the quantity you need to obtain (the Step 4: Check the solution. Read the problem again to make unknown). sure you have found all the solutions asked for in the problem. Does your answer make sense? That is, is the answer outra- Step 2: Develop a plan for solving the problem.SAMPLEConsider EXERCISE a 4.10 Calculating molar concentrations of ions possible path between the given information and the unknown. geously large or small or is it in the ballpark? Finally, are the This is usually a formula, an equation orWhat some are principle the molar you concentrationsunits and of significant each of the figures ions present correct? in a 0.025 M aqueous solution of calcium nitrate?

SOLUTION Analyse We are given the concentration of the ionic compound used to make the so- lutionSAMPLE and asked EXERCISE to determine 3.6 the concentrationsCalculating percentage of the ions incomposition the solution.

PlanCalculateWe can theuse percentage the subscr ipts of carbon, in the hydrogenchemical formulaand oxygen of the (by compound mass) in C 12toH deter-22O11. mine the relative ion concentrations. SOLUTION 2+ - Solve Calcium nitrate is composed of calcium ions (Ca ) and nitrate ions (NO3 ), so Analyse We are given a chemica l formula which shows the– elements and the2+ num- its chemicalber of atoms formula of each is Ca(NOelement3) 2in. Because the molecule. there are two NO3 ions for each Ca ion in the compound, each mole of Ca(NO3)2 that dissolves dissoci ates into 1 mol of 2+ - 2+ Ca Planand We2 mol see of that NO Equation3 . Thus, a3.10 solution relates that % compositionis 0.025 M in Ca(NOof an element3)2 is 0.025 in a M moleculein Ca to 3 andthe 2 : number0.025 M of= 0.050atoms M ofin each NO -element,. the atomic mass of each element and the for- mula mass of the molecule. The- formula mass can be calculated2+ as in Exercise 3.5 and Check The concentration of NO3 ions is twice that of Ca ions, as the subscript 2 the atomic- masses can be obtained from the periodic table. after the NO3 in the chemical formula Ca(NO3)2 suggests it should be. Solve Using Equation 3.10 and the periodic table to obtain atomic masses, we have (12)(12.0 u) %C = * 100% = 42.1% 342.0 u

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