Dispersion of matter

Processes that do not involve obvious dispersal of matter may nevertheless have preferred directions. For example. Figure 14-3 shows that when a hot block of metal is placed in a cold glass of water, the metal block cools and the water warms. This process continues until the two are at the same temperature. Whenever two objects at different temperatures contact each other, the object at higher temperature transfers energy to the object at lower temperature. 

Spontaneous processes result in the dispersal of matter and energy, hi many cases, however, the spontaneous direction of a process may not be obvious. Can we use energy changes to predict spontaneity To answer that question, consider two everyday events, the melting of ice at room temperature and the formation of ice in a freezer. 

The spontaneous direction of any process is toward greater dispersal of matter plus energy. If we are to apply this criterion in a quantitative way, we need ways to measure amounts of dispersal. Scientists analyze the constraints on a system to measure the dispersal of matter. The more the system is constrained, the less dispersed it is. Scientists do calculations on the flow of heat to measure changes in the dispersal of energy. 

Two marbles distributed among nine compartments provides an example ofW and its relationship to the dispersal of matter. 

When the NaCl dissolves, the ions disperse throughout the water. This allows the ions and the water molecules to transfer energy to each other. Dispersal of matter allows for more dispersal of energy. 

Taylor, G. I. (1954). The Dispersion of Matter in Turbulent Row Through a Pipe. Proc. R. Soc. London, A223,446. 

Taylor, G. I. 1954. The dispersion of matter in turbulent flow through a pipe. Proc. Roy. Soc. A223, 446-468. 

Taylor, G.I. The dispersion of matter in solvent flowing slowly through a tube. Proc. London Math. Soc., Ser. A 219,189-203. 1953. 

Understand the relationship of entropy to the dispersal of energy and dispersal of matter (disorder) in a system Use tabulated values of absolute entropies to calculate the entropy change, AS ... 

Dispersal of matter The degree to which the particles of a sample can be distributed in space also known as disorder. 

The key concept of entropy as an assessment of dispersal of matter and of energy is carefully developed to provide a firm foundation for later ideas including heat changes that accompany chemical and physical changes, prediction of reactions, and chemical bond stability. Throughout this chapter, many fundamental terms are rigorously defined, discussed, and illustrated for use throughout later studies of chemistry. 

Comprehensive chapters are presented on chemical thermod)mamics (Chapter 15) and chemical kinetics (Chapter 16). The discussion of entropy includes the concepts of dispersal of energy and dispersal of matter (disorder). The distinction between the roles of standard and nonstandard Gibbs free-energy change in predicting reaction spontaneity is clearly discussed. Chapter 15 is structured so that the first nine sections, covering thermochemistry and bond energies, could be presented much earlier in the course. Chapter 16 provides an early and consistent emphasis on the experimental basis of kinetics. 

Fig. 2.1 One fundamental type of spontaneous process is the disorderly dispersal of matter. This tendency accounts for the spontaneous tendency of a gas to spread into and fiU the container it occupies, it is extremely unlikely that all the particles will collect into one small region of the container. (In practice, the number of particles is of the order of 10 1)...

At the molecular level, the positive entropy change can be explained by the dispersal of matter and energy that accompanies the unraveling of the compact three-dimensional structure of lysozyme into a long, flexible chain that can adopt many different conformations as it writhes about in solution. 

---