Key-Concepts

Solubility is defined by the thermodynamic equilibrium of a solute between two phases, which in the context of this chapter are a solid phase and a liquid solution phase.The criterion for equilibrium between coexisting phases is that the temperature, pressure and molar free energies or chemical potentials of each individual species in each phase are equal.For a co-crystal, however, the sum of the molar free energies or chemical potentials of each co-crystal component plays a key role in determining phase equilibria. The molar Gibbs energy of the co-crystal A B in equilibrium with a solution phase is given by  

The activity of each component, a,-, is defined through the equation  

The right hand side of equation (11.4) is often referred to as the solubility product, Ksp. Co-crystal solubility product behavior is well documented in the literature.The activity of the solvent, which is the major component, is approximately unity and can be omitted from the equation. Co-crystal solubility means that a co-crystal is in equilibrium with a solution of a given thermodynamic activity product. Under these conditions, the solution is saturated with the given co-crystal phase. 

Strategies to enhance solubility are based on the free energy of solution, which involves not only the crystal lattice interactions, but the interactions between the solutes and the solvent. The two main factors associated with the overall free energy of solution are given by  

When attempting to explain the factors that contribute to co-crystal solubility, the focus is generally on solid state properties while solution phase contributions are not recognized. The situation becomes more complicated by attempting to assess co-crystal solubility by measurements under non-equilibrium conditions. 

A properly drawn Lewis structure shows the number of bonds and lone pairs present around each atom in a molecule. In a valid Lewis structure, each H has two electrons, and each second-row element has no more than eight. This is the first step needed to determine many properties of a molecule. 

Types of bonds [single, double, or triple] (Sections 1.3,1.9) 

The number of groups around an atom determines both its geometry (Section 1.6) and hybridization (Section 1.8). 

Number of groups Geometry Bond angle (°) Hybridization 

39 Two radioactive isotopes of iodine used for the diagnosis and treatment of thyroid disease have mass numbers of 123 and 131. For each isotope, give the foiiowing information (a) the number of protons (b) the number of neutrons (c) the number of eiectrons in the neutrai atom (d) the group number. 

Avogadro s number = 6.02 x 1023 = 1 mole number of moles = moiecSSwei,ht 

Naming Inorganic Ionic and Molecular Compounds and Acids (3.5-3.7) 

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In particular, in polar solvents, the surface of a colloidal particle tends to be charged. As will be discussed in section C2.6.4.2, this has a large influence on particle interactions. A few key concepts are introduced here. For more details, see [32] (eh 13), [33] (eh 7), [36] (eh 4) and [34] (eh 12). The presence of these surface charges gives rise to a number of electrokinetic phenomena, in particular electrophoresis. 

The Smith predictor is a model-based control strategy that involves a more complicated block diagram than that for a conventional feedback controller, although a PID controller is still central to the control strategy (see Fig. 8-37). The key concept is based on better coordination of the timing of manipulated variable action. The loop configuration takes into account the facd that the current controlled variable measurement is not a result of the current manipulated variable action, but the value taken 0 time units earlier. Time-delay compensation can yield excellent performance however, if the process model parameters change (especially the time delay), the Smith predictor performance will deteriorate and is not recommended unless other precautions are taken. 

These studies make use of the combined experience and training of a group of knowledgeable people in a structured setting. Some key concepts are ... 

Goetsch, David I., and Stanley B. Davis. ISO 14000 Environmental Management. Upper Saddle River, N.J. Prentice Hall, 2000. - Publisher information says that this book is written as a practical teaching resource and how-to guide. Each chapter contains a list of key concepts, review questions, critical thinking problems, and discussion cases with related questions. 

The cognitive approach has had a major influence in recent years on how human error is treated in systems such as chemical process plants and nuclear power generation. In the next section we shall describe some of the key concepts that have emerged from this work, and how they apply to the analysis of error in the CPI. Discussion of the cognitive view of human performance are contained in Reason (1990), Hollnagel (1993), Kantowitz and Fujita (1990), Hollnagel and Woods (1983), and Woods and Roth (1990). 

Hiickel models of molecular electronic structure enjoyed many years of popularity, particularly the r-electron variants. Authors sought to extract the last possible amount of information from these models, perhaps because nothing more refined was technically feasible at the time. Thus, for example, the inductive effect was studied. The inductive effect is a key concept in organic chemistry a group R should show a - -1 or a —I effect (according to the nature of the group R) when it is substituted into a benzene ring. 

The origin of the remarkable stereoselectivities displayed by chiral homogeneous catalysts has occasioned much interest and speculation. It has been generally assumed, using a lock-and-key concept, that the major product enantiomer arose from a rigid preferred initial binding of the prochiral olefin with the chiral catalyst. Halpren 48) on the basis of considerable evidence, reached the opposite conclusion the predominant product enantiomer arises from the minor, less stable diastereomer of the olefin-catalyst adduct, which frequently does not accumulate in sufficient concentration to be detected. The predominant adduct is in essence a dead-end complex for it hydrogenates at a much slower rate than does the minor adduct. 

I Summaries and Key Word lists help students by outlining the key concepts of the chapter. 

Select end of chapter Questions and Problems may be assigned in OWL and are cross-referenced in the Key Concepts list... 

Select end of chapter Questions and Problems may be assigned in OWL and are cross-referenced in the Key Concepts list 1. Deduce the sign of AS for a process from randomness considerations. (Example 17.1 Problems 7-14) Questions and Problems assignable in OWL 6,8,10,16 2. Calculate AS° for a reaction, using Table 17.1. (Example 17.2 Problems 17-22) 20... 

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