Solid molecular comparison

FIGURE 10.1 A molecular comparison of gases, liquids, and solids, (a) In gases, the particles feel little attraction for one another and are free to move about randomly, (b) In liquids, the particles are held close together by attractive forces but are free to move over one another, (c) In solids, the particles are rigidly held in an ordered arrangement. 

The atoms are embedded in the molecule and can only gain energy in the vibrational quanta characterised by the molecular structure. As an example we show in Fig. 1.2 the INS spectrum of a solid molecular system, Zeise s salt, K[Pt(C2H4)Cl3], and make comparison with its infrared and Raman spectrum.. Several points are apparent the most... 

Although very many experimental data have been accumulated on various uranium salts in the solid state, comparison of theoretical results for molecular species with crystallographic experimental data in general is not straightforward. 

SECTION 11.1 A Molecular Comparison of Gases, Liquids, and Solids 427... 

MOLECULAR COMPARISONS OF GASES, LIQUIDS, AND SOLIDS (section 11.1)... 

A MOLECULAR COMPARISON OF GASES, LIQUIDS, AND SOLIDS We begin with a comparison of solids, liquids, and gases from a molecular perspective. This comparison reveals the important roles that temperature and intermolecular forces play in determining the physical state of a substance. 

Masuda K, Tabata S, Sakata Y, Hayase T, Yonemochi E, Terada K (2005) Comparison of Molecular Mobility in the Glassy State Between Amorphous Indomethacin and SaUcin Based on Spin-Lattice Relaxation Times. Pharm Res 22(5) 797-805 Matsumoto T, Zografi G (1999) Physical properties of solid molecular dispersions of in-domethacin with poly (vinylpyrroUdone) and poly(vinylpyrrolidone-co-vinyl-acetate) in relation to indomethacin crystallization. Pharm Res 16(11) 1722-1728 Miyazaki T, Yoshioka S, Aso Y, Kojima S (2004) Ability of fxtlyvinylpyrrohdone and polyacrylic acid to inhibit the crystallization of amorphous acetaminophen. J Pharm Sci 93(11) 2710-2717 Miller D, Lechuga-BaUesteros D (2006) Rapid assessment of the structural reltixation behavior of amorphous pharmaceutical sohds effect of residual water on molecular mobility. Pharm Res 23(10) 2291-2305... 

Liquid, as an aggregate state, exists in a specific temperature interval - T . Near the liquid is close in physical properties and structure to the solid. Molecular mobility and intermolecular distances increase with heating. The higher and closer to critical the temperature, the closer the properties and behavior of the liquid to those of the gas. However, far from the critical temperature T< T ) the liquid is closer to the solid than to the gas. In particular, it follows from a comparison of enthalpies of melting and evaporation AH < A//yap. For example, for benzene = 11 kJ/mol and = 48 kJ/mol, i.e., the transition of the substance from the solid to liquid state requires a much lower energy consumption than that from the liquid to vaporlike state. 

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