Pharmaceutical Faculty of Commenius University LABORATORY MANUAL FOR PHYSICAL CHEMISTRY 1996 Bratislava DEPARTMENT OF PHYSICAL CHEMISTRY, FaF UK BRATISLAVA Editor: Doc. RNDr. František Kopecký,CSc. Contributors: Doc. RNDr. František Kopecký,CSc., Ing. Pavol Kaclík, RNDr. Tomáš Fazekaš Laboratory manual for physical chemistry, First edition Copyright 1996 by Faculty of Pharmacy, Commenius University, Bratislava Interior and Cover design: Tomáš Fazekaš 1-2 CONTENTS 1. DETERMINATION OF MOLAR MASS FROM FREEZING POINT DEPRESSION ...........................1-5 1.1 THEORY.......................................................................................................................................................1-5 1.2 TASK ...........................................................................................................................................................1-9 1.3 EQUIPMENT AND CHEMICALS ......................................................................................................................1-9 1.4 METHOD......................................................................................................................................................1-9 1.5 PROCESSING THE RESULTS.........................................................................................................................1-10 2. PARTITION COEFFICIENT OF SUCCINIC ACID ................................................................................2-12 2.1 THEORY.....................................................................................................................................................2-12 2.2 TASK .........................................................................................................................................................2-13 2.3 EQUIPMENT AND CHEMICALS ....................................................................................................................2-13 2.4 METHOD....................................................................................................................................................2-13 2.5 PROCESSING THE RESULTS.........................................................................................................................2-14 3. DETERMINATION OF THE LIQUID-VAPOUR EQUILIBRIUM IN A BINARY SYSTEM OF MISCIBLE LIQUIDS ............................................................................................................................................3-16 3.1 THEORY.....................................................................................................................................................3-16 3.2 TASK .........................................................................................................................................................3-18 3.3 EQUIPMENT AND CHEMICALS ....................................................................................................................3-18 3.4 METHOD....................................................................................................................................................3-19 3.5 PROCESSING THE RESULTS.........................................................................................................................3-20 4. KINETICS OF DISSOLUTION OF SOLID SUBSTANCES ....................................................................4-21 4.1 THEORY.....................................................................................................................................................4-21 4.2 SOME REMARKS ON CHEMICAL KINETICS...................................................................................................4-22 4.3 METHOD....................................................................................................................................................4-23 4.4 DEVICE AND MATERIALS ...........................................................................................................................4-23 4.5 EXPERIMENTAL .........................................................................................................................................4-24 4.6 PROCESSING THE RESULTS.........................................................................................................................4-25 5. DETERMINATION OF ADSORPTION ISOTHERM OF ACETIC ACID ON ACTIVATED CHARCOAL...........................................................................................................................................................5-26 5.1 THEORY.....................................................................................................................................................5-26 5.2 TASK .........................................................................................................................................................5-26 5.3 EQUIPMENT AND CHEMICALS ....................................................................................................................5-27 5.4 METHOD....................................................................................................................................................5-27 5.5 PROCESSING THE RESULTS.........................................................................................................................5-28 6. ELECTROCHEMICAL CELLS AND ELECTRODES ............................................................................6-29 6.1 PRINCIPLES AND THE USE OF ELECTROCHEMICAL CELLS ...........................................................................6-29 6.2 CELL DIAGRAMS, CELL POTENTIAL AND STANDARD POTENTIALS ..............................................................6-31 6.3 ELECTRODE POTENTIALS AND THE NERNST EQUATION..............................................................................6-33 7. POTENTIOMETRIC MEASUREMENT OF PH USING HYDROGEN ELECTRODE.......................7-36 7.1 THEORY - PH OF AQUEOUS SOLUTIONS .....................................................................................................7-36 7.2 THEORY OF HYDROGEN ELECTRODE ..........................................................................................................7-37 7.3 DEVICE AND MATERIALS ...........................................................................................................................7-39 7.4 EXPERIMENTAL .........................................................................................................................................7-40 7.5 PROCESSING THE RESULS...........................................................................................................................7-40 8. POTENTIOMETRIC MEASUREMENT OF PH USING GLASS ELECTRODE.................................8-41 8.1 THEORY.....................................................................................................................................................8-41 8.2 DEVICE AND MATERIALS ...........................................................................................................................8-44 8.3 EXPERIMENTAL .........................................................................................................................................8-44 9. POTENTIOMETRIC DETERMINATION OF THE DISSOCIATION CONSTANT OF WEEK ACID9-46 9.1 THEORY ....................................................................................................................................................9-46 9.2 EQUIPMENT AND CHEMICALS ....................................................................................................................9-48 9.3 TASK .........................................................................................................................................................9-48 9.4 PREPARATION OF SOLUTIONS ....................................................................................................................9-49 9.5 POTENTIOMETERIC DETERMINATION OF PH...............................................................................................9-49 9.6 PROCESSING OF THE MEASURED DATA ......................................................................................................9-49 10. CHECKING THE FUNCTION OF THE BROMIDE ION-SELECTIVE ELECTRODE ...............10-52 10.1 THEORY - BROMIDE ISE..........................................................................................................................10-52 10.2 ACTIVITY AND ACTIVITY COEFFICIENT OF A STRONG ELECTROLYTE .......................................................10-54 10.3 PRACTICAL TASK.....................................................................................................................................10-54 10.4 DEVICE AND MATERIALS................................................................................................................10-55 10.5 EXPERIMENTAL .................................................................................................................................10-55 11. EXCERCISES ..........................................................................................................................................11-59 11.1 MOLECULAR WEIGHT, MOLAR MASS, AMOUNT OF SUBSTANCE, MOLAR VOLUME CONCENTRATION OF SOLUTIONS ..........................................................................................................................................................11-59 11.2 RADIOACTIVITY, RADIOACTIVE DECAY ....................................................................................11-59