Liquid, definition structure

In the isoelectronic B3H7 LB species, the liquid phase structure (VII-A13) is definitely indicated to be correct by Parry and Paine 39, 109), rather than a structure with elements of both VII-A13 and II-A13 which may be more stable in the crystal phase 97). 

Solid phases of binary systems, like the liquid phases, are very commonly of variable composition. Here, as with the liquid, the stable range of composition is larger, the more similar the two components are. This of course is quite c-ontrary to the chemists notion of definite chemical composition, definite structural formulas, etc., but those notions are really of extremely limited application. It happens that the solid phases in the system water—ionic compound are often of rather definite composition, and it is largely from this rather special case that the idea of definite compositions in solids has become so firmly rooted. In such a system, there are normally two solid phases ice and the crystalline ionic compound. Ice can take up practically none of any ionic compound, so that it has practically no range of compositions. And many ionic crystals... 

A common feature of all theories is that a definite structure of liquid water is due to the hydrogen bonding between molecules and that the structure is in the dynamic state as the hydrogen bonds break and reform with high frequency. 

It should be pointed out that along with this definition which describes the liquid ciystalline state as a phase state, use is often made of the term "liquid crystalline structure" which is indicative only of a certain orientation ordering in a system. Despite the narrower meaning of the latter term, the notion of a liquid crystalline structure (or ordering) is widely used in the literature on structural polymer studies, therefore, in some instances, we shall use this term as well. 

In the theory of liquids, the structure is usually defined in terms of the molecular distribution function. This definition, though quantitative, is not satisfactory when applied to liquid water. What is needed is a number that measures the extent of the structure of water, as is currently understood, with the help of which one can compare the structures of the liquid in two different states. 

Note, that we are calling second liquid "nonstructural" only in respect to ordinary liquid which has the property Con. In reality, each liquid has a definite structure (Con or Loc) each liquid, in its way, displays a quality which inherent in solid (crystal). Otherwise, the both liquids are quasicrystalline, but prefix "quasi" should be imderstood differently, depending on that which liquid is meant. 

At the beginning of the Gap the water content of the system is not enough to allow a definite structural liquid-crystalline configuration, but the structured entities, within the system, may be indeed oriented and spatially ordered by means of an impressed electric field. Therefore a Kerr-like effect can be observed, due to the optical anisotropy induced by the field. 

Polarized microscopy can be used as one of several methods for the assessment of liquid-crystalline structure. Because of its simplicity it deserves to be used, but it is equally clear that the X-ray diffraction methods, particularly on aligned samples, provide more definite answers. 

It was made clear in Chapter II that the surface tension is a definite and accurately measurable property of the interface between two liquid phases. Moreover, its value is very rapidly established in pure substances of ordinary viscosity dynamic methods indicate that a normal surface tension is established within a millisecond and probably sooner [1], In this chapter it is thus appropriate to discuss the thermodynamic basis for surface tension and to develop equations for the surface tension of single- and multiple-component systems. We begin with thermodynamics and structure of single-component interfaces and expand our discussion to solutions in Sections III-4 and III-5. 

Chemicals exist as gases, liquids or solids. Solids have definite shapes and volume and are held together by strong intermolecular and interatomic forces. For many substances, these forces are strong enough to maintain the atoms in definite ordered arrays, called crystals. Solids with little or no crystal structure are termed amorphous. 

The structure of the chapter is as follows. First, we start with a brief introduction of the important theoretical developments and relevant interesting experimental observations. In Sec. 2 we present fundamental relations of the liquid-state replica methodology. These include the definitions of the partition function and averaged grand thermodynamic potential, the fluctuations in the system and the correlation functions. In the second part of... 

A distinction between a solid and liquid is often made in terms of the presence of a crystalline or noncrystalline state. Crystals have definite lines of cleavage and an orderly geometric structure. Thus, diamond is crystalline and solid, while glass is not. The hardness of the substance does not determine the physical state. Soft crystals such as sodium metal, naphthalene, and ice are solid while supercooled glycerine or supercooled quartz are not crystalline and are better considered to be supercooled liquids. Intermediate between the solid and liquid are liquid crystals, which have orderly structures in one or two dimensions,4 but not all three. These demonstrate that science is never as simple as we try to make it through our classification schemes. We will see that thermodynamics handles such exceptions with ease. 

A crystalline solid is a solid in which the atoms, ions, or molecules lie in an orderly array (Fig. 5.16). A crystalline solid has long-range order. An amorphous solid is one in which the atoms, ions, or molecules lie in a random jumble, as in butter, rubber, and glass (Fig. 5.17). An amorphous solid has a structure like that of a frozen instant in the life of a liquid, with only short-range order. Crystalline solids typically have flat, well-defined planar surfaces called crystal faces, which lie at definite angles to one another. These faces are formed by orderly layers of atoms (Box 5.1). Amorphous solids do not have well-defined faces unless they have been molded or cut. 

In order to discuss the various techniques we must distinguish between diffusive and non-diffusive systems (J8). Diffusive systems, such as liquids, are characterized by the eventual diffusion of particles over all of the available space non-diffusive systems such as solids, glasses and macromolecules with a definite average structure are characterized by time independent average positions around which the atoms fluctuate. 

This definition of electrochemistry disregards systems in which nonequilibrium charged species are produced by external action in insulators for example, by electric discharge in the gas phase (electrochemistry of gases) or upon irradiation of liquid and sohd dielectrics (radiation chemistry). At the same time, electrochemistry deals with certain problems often associated with other fields of science, such as the structure and properties of sohd electrolytes and the kinetics of ioific reactions in solutions. 

---