Physical Properties of Solids

The properties of a solid which are of greatest interest to an organic chemist are vapor pressure, melting point, and solubility. The most common methods of purifying and characterizing solids depend on these properties. Other properties such as crystal structure, density, and refractive index are now rarely used and will not be considered here. 

The vapor pressure of a solid may be determined in much the same way as for a liquid. The solid is placed in a container, which is then evacuated. The pressure in the container is measured, and if all foreign 

The vapor pressure-temperature curves for B-pentane and neopentane are shown in Fig. 2-1. The break in the neopentane curve occurs 

The most striking fact is the very high vapor pressure of solid neopentane its vapor pressure is higher than that of liquid B-pentane at 

These enthalpies and entropies are of course a function of the structure of the compound. The thermodynamic quantities for vaporization were discussed previously (page 14), and it was seen that this factor varied in a reasonably predictable way with a change in structure. The thermodynamic quantities for sublimation are the sum of those for vaporization and for fusion, and it is now necessary to consider the latter. These are not as simple a function of the structure as is the boiling point, because they depend on the crystal structure which is possible with the compound and on short-range attractive forces which operate in the crystal. Certain generalizations may, however, be made. 

The majority of the materials we use and handle every day are solid. We take advantage of their physical properties in manifold ways. The properties are intimately related to the structures. In the following we will deal only briefly with a few properties that are directly connected with some structural aspects. Many other properties such as electrical and thermal conductivity, optical transparency and reflectivity, color, luminescence etc. require the discussion of sophisticated theories that are beyond the scope of this book. 

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Table 1. Physical Properties of Solid Acrylamide Monomer ...

Graham, R.A., Impact Techniques for the Study of Physical Properties of Solids Under Shock-Wave Loading, J. Base Engrg. Trans. ASME 89, 911-918 (1967). 

In this chapter physical properties of solids at finite strain within their purely elastic ranges will be investigated. Although the strain levels of a few percent are small relative to the total compressions of typical shock-compression studies, they are large compared to those typically encountered in higher-order elastic property investigations. 

We have to refine our atomic and molecular model of matter to see how bulk properties can be interpreted in terms of the properties of individual molecules, such as their size, shape, and polarity. We begin by exploring intermolecular forces, the forces between molecules, as distinct from the forces responsible for the formation of chemical bonds between atoms. Then we consider how intermolecular forces determine the physical properties of liquids and the structures and physical properties of solids. 

This section discusses the techniques used to characterize the physical properties of solid catalysts. In industrial practice, the chemical engineer who anticipates the use of these catalysts in developing new or improved processes must effectively combine theoretical models, physical measurements, and empirical information on the behavior of catalysts manufactured in similar ways in order to be able to predict how these materials will behave. The complex models are beyond the scope of this text, but the principles involved are readily illustrated by the simplest model. This model requires the specific surface area, the void volume per gram, and the gross geometric properties of the catalyst pellet as input. 

The type of bonding in a substance depends upon the kinds of atoms it contains and the forces of attraction between those atoms. If you know the physical properties of a substance, you can often predict the type of bonding in the substance. Table 4.5 summarizes the types of forces of attraction and the physical properties of solids with different types of bonding discussed in this section. In Investigation 4-B, you will design an experiment in which you predict the type of bonding in various substances, then test your prediction. 

The physical properties of solid fuels can be modified to a certain extent. It is the size, shape and density which are easy to change. Solid biofuels which are modified are here referred to as refined solid biofuels, see Figure 30. 

Every example of a vibration we have introduced so far has dealt with a localized set of atoms, either as a gas-phase molecule or a molecule adsorbed on a surface. Hopefully, you have come to appreciate from the earlier chapters that one of the strengths of plane-wave DFT calculations is that they apply in a natural way to spatially extended materials such as bulk solids. The vibrational states that characterize bulk materials are called phonons. Like the normal modes of localized systems, phonons can be thought of as special solutions to the classical description of a vibrating set of atoms that can be used in linear combinations with other phonons to describe the vibrations resulting from any possible initial state of the atoms. Unlike normal modes in molecules, phonons are spatially delocalized and involve simultaneous vibrations in an infinite collection of atoms with well-defined spatial periodicity. While a molecule s normal modes are defined by a discrete set of vibrations, the phonons of a material are defined by a continuous spectrum of phonons with a continuous range of frequencies. A central quantity of interest when describing phonons is the number of phonons with a specified vibrational frequency, that is, the vibrational density of states. Just as molecular vibrations play a central role in describing molecular structure and properties, the phonon density of states is central to many physical properties of solids. This topic is covered in essentially all textbooks on solid-state physics—some of which are listed at the end of the chapter. 

Physical properties of solid materials which are greatly influenced by the presence of defects of lattice order in real single crystals are called structural-sensitive properties, and are distinguished from intrinsic properties, which are determined by the elements constituting the crystal, for example the chemical bonds, the structure, etc. Color, plasticity, glide, and semiconductor properties are structural-sensitive properties, whereas density, hardness, elasticity, and optical, thermal, and magnetic properties are the intrinsic properties. Structural-sensitive... 

Physical properties of solid polyphosphate glasses and their melts are also in accord with the conclusions drawn from chemical studies. The X-ray diffraction pattern shows the polyphosphate anions to consist of long chains of P04 tetrahedra (32) and the same conclusion is reached by studying the double refraction of fibers formed by rapidly drawing supercooled melts of Graham s salt (101). 

Hasegawa A, Kawamura R, Nakagawa H, Sugimoto K. Physical properties of solid dispersions of poorly water-soluble drugs with enteric coating agents. Chem Pharm Bull 1985 33 3429-3435. 

Fig. 11.—Relation between Hardness and other Physical Properties of Solid Solutions (Diagrammatic).

The physical properties of solid acrylamide monomer are summarized in Table 1. Typical physical properties of 50% solution in water appear in... 

TABLE 1. PHYSICAL PROPERTIES OF SOLID ACRYLAMIDE MONOMER... 

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