Macroscopic things

Therefore, one may say that Chemistry is a special way to see the physical phenomena, there where the mass or nirmber of particles does not count in macroscopic way. And this is the first big leap of Chemistry it seems to deal with macroscopic things when in fact it deals with observable... 

But there is one sort of property realizer that mental properties have to have if their instances are realized in microphysical states of affairs. For any type of microphysical state of affairs that can be the maximally determinate realizer of an instance of a particular macrophysical property, there is a property something has just in case its career includes a microphysical state of affairs of that type that realizes an instance of that property. Let s speak of these as properties of macroscopic entities that embed maximally determinate microphysical states of affairs that are property instance realizers - call them microphysical-state-of-affairs-embedding properties, or MSE-properties. If a property is such that an instance of it can be realized in a maximally determinate microphysical state of affairs of a certain type, then the corresponding MSE-property will be among its possible property realizers. Assuming physicalism, mental properties will have such properties as realizers. But so also will all other properties of macroscopic things - or, rather, all other properties that are not themselves MSE-properties. Properties such as shape, mass, electrical charge, are ones whose different instances are realized in microphysical states of affairs of different sorts, and so ones that are realized in a variety of MSE-properties. 

If by a first-order property we mean one the possession of which by a thing does not consist in the possession by that thing of some other property, and if by a second-order property we mean one the possession of which by a thing does consist in the possession by that thing of some other property, then the only first-order properties of macroscopic things will be MSE-properties, and all of their other properties will be second order. On this understanding of the first-order/second-order distinction, mental properties are second order — but so are all of the other properties of macroscopic things we can refer to. To preserve a distinction. 

You can view many things in chemistry on both the macroscopic level (the level that we can directly observe) and the microscopic level (the level of atoms and molecules. Many times, observations at the macroscopic level can influence the theories and models at the microscopic level. Theories and models at the microscopic level can suggest possible experiments at the macroscopic level. We express the properties of matter in both of these ways. 

Reaction rates are macroscopic averages of the number of microscopical molecules that pass from the reactant to the product valley in the potential hypersurface. An estimation of this rate can be obtained from the energy of the highest point in the reaction path, the transition state. This approach will however fail when the reaction proceeds without an enthalpic barrier or when there are many low frequency modes. The study of these cases will require the analysis of the trajectory of the molecule on the potential hypersurface. This idea constitutes the basis of molecular dynamics (MD) [96]. Molecular dynamics were traditionally too computationally demanding for transition metal complexes, but things seem now to be changing with the use of the Car-Parrinello (CP) method [97]. This approach has in fact been already succesfully applied to the study of the catalyzed polymerization of olefins [98]. 

Obviously, if we know experimentally the behavior of the macroscopic ordering parameter with T, we may determine the corresponding coefficients of the Landau expansion (eq. 2.52). However, things are not so easy when different transitions are superimposed (such as, for instance, the displacive and order-disorder transitions in feldspars). In these cases the Landau potential is a summation of terms corresponding to the different reactions plus a couphng factor associated with the common elastic strain. 

When Dirac completed work on his theory in 1928, it was a notable success. Among other things, it explained electron spin, which turned out to be a relativistic effect, rather than something analogous to the spin of a macroscopic object like a top. But the theory also made what seemed to be a very strange prediction. If Dirac s theory was correct, then there had to exist particles that had properties like the electron, but that carried a positive rather than a negative charge. At the time, such particles, called positrons, had never been observed. 

Surface tension and contact angle phenomena play a major role in many practical things in life. Whether a liquid will spread on a surface or will break up into small droplets depends on the above properties of interfaces and determines well-known operations such as detergency and coating processes and others that are, perhaps, not so well known, for example, preparation of thin films for resist lithography in microelectronic applications. The challenge for the colloid scientist is to relate the macroscopic effects to the interfacial properties of the materials involved and to learn how to manipulate the latter to achieve the desired effects. Vignette VI provides an example. 

Schematic illustrations of these processes are shown in Figure 6.8. Two things must be remembered about these sketches One unit of surface is affected by the processes, and the shape of the affected area is immaterial. It is understood that these are elements of volume and area that are portions of macroscopic samples. Our interest is in the free energy change accompanying each process.

One of the most important things to bear in mind in studying van der Waals forces is that this topic has ramifications that extend far beyond our discussion here. Van der Waals interactions, for example, contribute to the nonideality of gases and, closer to home, gas adsorption. We also see how these forces are related to surface tension, thereby connecting this material with the contents of Chapter 6 (see Vignette X below). These connections also imply that certain macroscopic properties and measurements can be used to determine the strength of van der Waals forces between macroscopic objects. We elaborate on these ideas through illustrative examples in this chapter. 

Equilibrium thermodynamics is the most important, most tangible result of classical thermodynamics. It is a monumental collection of relations between state properties such as temperature, pressure, composition, volume, internal energy, and so forth. It has impressed, maybe more so overwhelmed, many to the extent that most were left confused and hesitant, if not to say paralyzed, to apply its main results. The most characteristic thing that can be said about equilibrium thermodynamics is that it deals with transitions between well-defined states, equilibrium states, while there is a strict absence of macroscopic flows of energy and mass and of driving forces, potential differences, such as difference in pressure, temperature, or chemical potential. It allows, however, for nonequilibrium situations that are inherently unstable, out of equilibrium, but kinetically inhibited to change. The driving force is there, but the flow is effectively zero. 

The basic question in all of thermodynamics is A certain system is under such and such constraints, what is the equilibrium state that it can go to spontaneously The amazing thing is that this question can be answered by making macroscopic measurements. Thermodynamics does not deal with the question as to how long it will take to reach equilibrium. We now have seven criteria for equilibrium in a one-phase system with one species and only PV work. The criteria of equilibrium provided by these thermodynamic potentials are (dt/)S K n 0, (dH)SPn < 0, (d/4)r K 0, (dG)rp <0, (dC/[/r])s v >(1 < 0,... 

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