EXPERIMENTS IN PHYSICAL CHEMISTRY SIXTH EDITION DAVID P. SHOEMAKER CARL W. GARLAND JOSEPH W. NIBLER The Late Emeritus Professor of Chemistry Professor of Chemistry Professor of Chemistry Oregon State University Massachusetts Institute of Technology Oregon State University THE MCGRAW-HILL COMPANIES, INC. New York St. Louis San Francisco Auckland Bogota Caracas Lisbon London Madrid Mexico City Milan Montreal New Delhi San Juan Singapore Sydney Tokyo Toronto
Contents Preface I. INTRODUCTION Organization of the Book Preparation for an Experiment Execution of an Experiment Safety Recording of Experimental Data Literature Work Reports Sample Report Special Projects 2 4 4 6 7 9 10 13 25 II. TREATMENT OF EXPERIMENTAL DATA 27 A. Caiculations and Presentation of Data Significant Figures Precision of Caiculations Analytical Methods Numerical Methods Graphs and Graphical Methods Exercises B. Uncertainties in Data and Results Errors Rejection of Discordant Data Statistical Treatment of Random Errors Significance Testing Propagation of Errors Case History of an Error Evaluation 27 28 29 30 31 32 36 36 37 40 42 51 55 61
Fundamental Limitations on Instrumental Precision 64 Summary 66 Exercises 68 III. USE OF COMPUTER SOFTWARE 71 Word Processors 71 Spreadsheets 72 Symbolic Mathematics Programs 82 Quantum Mechanical Programs 85 Exercises 88 IV. GASES 90 1. Gas Thermometry 90 2. Joule-Thomson Effect 97 3. Heat-Capacity Ratios for Gases 105 V. TRANSPORT PROPERTIES OF GASES 117 Kinetic Theory of Transport Phenomena 117 4. Viscosity of Gases 126 5. Diffusion of Gases 134 VI. THERMOCHEMISTRY 145 Principles of Calorimetry 145 6. Heats of Combustion 152 7. Strain Energy of the Cyclopropane Ring 158 8. Heats of Ionic Reaction 167 VII. SOLUTIONS 172 9. Partial Molal Volume 172 10. Cryoscopic Determination of Molecular Weight 179 11. Freezing-Point Depression of Strong and Weak Electrolytes 188 12. Chemical Equilibrium in Solution 193 VIII. PHASE EQUILIBRIA 199 13. Vapor Pressure of a Pure Liquid 199 14. Binary Liquid-Vapor Phase Diagram 207 15. Binary Solid-Liquid Phase Diagram 215 16. Liquid-Vapor Coexistence Curve and the Critical Point 222 IX. ELECTROCHEMISTRY 228 17. Conductance of Solutions 228 18. Temperature Dependence of EMF 238 19. Activity Coefficients from Cell Measurements 241 X. CHEMICAL KINETICS 247 20. Method of Initial Rates: Iodine Clock 247 21. NMR Study of a Reversible Hydrolysis Reaction 256 22. Enzyme Kinetics: Inversion of Sucrose 264
Contents VM 23. Kinetics of the Decomposition of Benzenediazonium Ion 275 24. Gas-Phase Kinetics 280 XI. SURF ACE PHENOMENA 291 25. Surface Tension of Solutions 291 26. Physical Adsorption of Gases 300 XII. MACROMOLECULES 310 27. Osmotic Pressure 310 28. Intrinsic Viscosity: Chain Linkage in Polyvinyl Alcohol 317 29. Helix-Coil Transition in Polypeptides 326 XIII. ELECTRIC AND MAGNETIC PROPERTIES 335 30. Dipole Moment of Polar Molecules in Solution 335 31. Dipole Moment of HCl Molecules in the Gas Phase 346 32. Magnetic Susceptibility 359 33. NMR Determination of Paramagnetic Susceptibility 369 XIV. SPECTROSCOPY 378 34. Absorption Spectrum of a Conjugated Dye 378 35. Infrared Spectroscopy: Vibrational Spectrum of S0 2 382 36. Raman Spectroscopy: Vibrational Spectrum of CC1 4 389 37. Vibrational-Rotational Spectra of HCl and DC1 397 38. Vibrational-Rotational Spectra of Acetylenes 404 39. Band Spectrum of Nitrogen 416 40. Absorption and Emission Spectra of Molecular Iodine 425 41. Electron Spin Resonance Spectroscopy 434 42. NMR Determination of Keto-Enol Equilibrium Constants 446 43. NMR Study of Gas-Phase DCl-HBr Isotopic Exchange Reaction 454 44. Solid-State Lasers: Radiative Properties of Ruby Crystals 462 XV. SOLIDS 472 45. Determination of Crystal Structure by X-ray Diffraction 472 46. Single-Crystal X-ray Diffraction with the Buerger Precession Camera 487 47. Lattice Energy of Solid Argon 506 48. Statistical Thermodynamics of Iodine Sublimation 514 XVI. COMPUTER INTERFACING 529 Computer Data Types 530 Hardware 533 Software 535 Computer Programming 538 Interfacing with Experiments 542 XVII. ELECTRONIC DEVICES AND MEASUREMENTS 554 Circuit Elements 554 Semiconductor Devices 558 Operational Amplifiers 566
VIII Contents Analog-to-Digital Conversion 571 Digital Multimeters 573 Potentiometer Circuits 575 Wheatstone Bridge Circuits 578 Capacitance Measurements 581 XVIII. TEMPERATURE 584 Temperature Scales 584 Triple-Point and Ice-Point Cell 588 Thermometers 589 Temperature Control 604 XIX. VACUUM TECHNIQUES 615 Introduction 615 Theoretical Background 615 Pumping Speed for a System 616 Desorption and Virtual Leaks 621 Pumps 622 Vacuum Gauges 630 Miscellaneous Vacuum Components 635 Design of Vacuum Lines 638 Leak Detection 640 Safety Considerations 642 XX. INSTRUMENTS 644 Balances 644 Barometers 648 Oscilloscopes 648 ph Meters 652 Polarimeters 654 Radiation Counters 656 Recorders, Plotters, and Printers 656 Refractometers 657 Signal-Averaging Devices 661 Spectroscopic Components 663 Spectroscopic Instruments 676 Timing Devices 683 XXI. MISCELLANEOUS PROCEDURES 685 Volumetrie Procedures 685 Purification Methods 690 Gas-Handling Procedures 691 Electrodes for Electrochemical Cells 697 Materials for Construction 698 Solders and Adhesives 704 Tubing Connections 706 Shopwork 708
XXII. LEAST-SQUARES FITTING PROCEDURES 710 Introduction 710 Foundations of Least Squares 711 Weights 716 Rejection of Discordant Data 718 Goodness of Fit 719 Comparison of Models 722 Uncertainties in the Parameters 725 Summary of Procedures 727 Sample Least-Squares Calculation 728 APPENDIXES 733 A. Glossary of Symbols 733 B. International System of Units and Concentration Units 736 C. Safety 739 D. Literature Work 746 E. Research Journals 753 F. Numerical Methods of Analysis 755 G. Barometer Corrections 764 Index 765 Endpapers Physical Constants and Conversion Factors Energy Conversion Table Relative Atomic Masses of the Elements front front back