Physical properties, pure substances organic compounds

References D. D. Wagman, et ah, The NBS Tables of Chemical Thermodynamic Properties, in J. Phys. Chem. Ref. Data, 11 2,1982 M. W. Chase, et ah, JANAF Thermochemical Tables, 3rd ed., American Chemical Society and the American Institute of Physics, 1986 (supplements to JANAF appear in J. Phys. Chem. Ref. Data) Thermodynamic Research Center, TRC Thermodynamic Tables, Texas A M University, College Station, Texas I. Barin and O. Knacke, Thermochemical Properties of Inorganic Substances, Springer-Verlag, Berlin, 1973 J. B. Pedley, R. D. Naylor, and S. P. Kirby, Thermochemical Data of Organic Compounds, 2nd ed.. Chapman and Hall, London, 1986 V. Majer and V. Svoboda, Enthalpies of Vaporization of Organic Compounds, International Union of Pure and Applied Chemistry, Chemical Data Series No. 32, Blackwell, Oxford, 1985. 

When presented with a mixture of unknown organic compounds to identify, the modern chemist has an arsenal of tools available to assist her. The fist task is typically to separate the mixture into pure substances. Many separation processes have been developed for this purpose. These techniques may utilize differences in the molecules to separate them. Such differences may be in size, charge, chemical affinity, or physical properties. By repeatedly applying separation techniques, compounds can also be made increasingly pure. A few of the more common laboratory separation process are listed below ... 

Not only are physical properties used to characterize a specific organic compound, buf they are often used to compare one compound to another. Examples of fhis approach are illustrated in Chapter 9, Qualitative Identification of Organic Compounds. The route to identification of an unknown organic species has become increasingly dependent on the measurement of the physical properties of the pure substance. 

Chirality Certain organic compounds can exist as nonsuperim-posable mirror-image twins. These compounds are said to be chiral. The pure enantiomer of a compound can rotate plane-polarized light. Enantiomers have identical physical properties but exhibit different chemical properties toward another chiral substance. 

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