The Variety of Solutions

With most of our familiar solutions, water is the solvent and the solution is called an aqueous solution. Milk, juices, soft drinks, alcoholic drinks, and sports beverages are all aqueous solutions. Ponds, lakes, and oceans are all aqueous solutions in which the solutes are dissolved solids, gases, and various organic compounds. The main component of blood is water, so blood is an aqueous solution. 

Gasoline is a homogeneous mixture of many different componnds in which water is not the solvent—in fact, one nsnally takes care that gasoline is not contaminated with water. Paints are solntions in which water may or may not be the solvent fri oil-based paints oil is the solvent. 

Air is also a solntion. fri air, the gas present in greatest qnantity is nitrogen, so is the solvent All other gases—mostly oxygen (O ), argon (Ar), carbon dioxide (COf), and water vapor—are the solntes. 

Aqueous means containing, or dissolved in, water. In an aqueous solution, water is the solvent. 

By number of molecules, the atmosphere Is 78 percent N, 21 percent and l percent Ar, with only trace amounts of all other gases. 

---

Suppose you are in charge of cleaning up and doing inventory in the chemistry stockroom. Your first job is to catalog the variety of solutions that are on the shelf. One of the solutions you find is a tightly stoppered, well-labeled bottle of O.lOOMNaOH. 

Theory alone cannot provide a criterion for the best association constant. However, the variety of solution models leads usually to more or less satisfactory association constants when all of the relevant experimental data including their dependence on temperature and pressure are considered. Once more, chemical evidence is a good criterion for the selection of the appropriate model. It will be shown in the following sections that the identification of the critical distance of association with the cut-off distance of the short-range forces, R, in our chemical model yields association constants which are. almost independent of the experimental method of their determination. 

Unlike the original Marcus theory, which uses the continuum model for solvent, the method described above can provide a microscopic picture for the solvent fluctuation. It will be of great interest to explore the chemistry of the electron transfer reaction, including the specific dependence of the rate constant on the variety of solute and solvent. 

Most important from our point of view, however, is how this case challenged the conditionality of the trust balance and exposed potential fragilities when critical issues about the socio-economic distribution of risk were at stake. The risk-cost-benefit considerations that were thus introduced involved rather complex questions What was really the magnitude of the risks involved How much risk reduction would be achieved by the variety of solutions available in different operational situations What were the compliance costs, and did they justify the (contested) risk reduction compared to alternative allocations of risk-reducing efforts And, of course, what was really the impact of welfare concerns for the workers in these requirements ... 

The uncertainties highlighted by the variety of solutions adopted demonstrate the lack of a universally recognized method for the design of these joints which also satisfies the need for limiting the stresses in the flange and bolts, and the leak proofing requirements. The various standards are quoted in Section 14-3-5. 

As a consequence of such experiences, it is helpful to accept the variety of solutions in software landscapes and not try to go against the tide. These solutions are usually driven by business needs. Variety should thus not generally be seen as a... 

The design of bionanoreactors is based on encapsulation/insertion of active compounds (proteins, enzymes, mimics) inside polymeric supramolecular assemblies, such as dendrimers, capsules, and vesicles, in which they can act in situ while being protected from proteolytic attack [3,6]. These supramolecular assemblies should allow the passage of products or substrates to the inner spaces where the active compounds are located in order to support reactions confined within their structures. Various approaches to providing accessibility to the inner reaction space of the polymer assemblies are presented, even though not all have been used in the design of nanoreactors, in order to give an overview of the variety of solutions that can be expected to advance this field of science. 

A typical arrangement for a voltammetric electrochemical cell is shown in Figure 11.28. Besides the working, reference, and auxiliary electrodes, the cell also includes a N2 purge line for removing dissolved O2 and an optional stir bar. Electrochemical cells are available in a variety of sizes, allowing for the analysis of solution volumes ranging from more than 100 mL to as small as 50 )+L. 

The sonochemistry of solutes dissolved in organic Hquids also remains largely unexplored. The sonochemistry of metal carbonyl compounds is an exception (57). Detailed studies of these systems led to important mechanistic understandings of the nature of sonochemistry. A variety of unusual reactivity patterns have been observed during ultrasonic irradiation, including multiple ligand dissociation, novel metal cluster formation, and the initiation of homogeneous catalysis at low ambient temperature (57). 

There are two problems in the manufacture of PS removal of the heat of polymeriza tion (ca 700 kj /kg (300 Btu/lb)) of styrene polymerized and the simultaneous handling of a partially converted polymer symp with a viscosity of ca 10 mPa(=cP). The latter problem strongly aggravates the former. A wide variety of solutions to these problems have been reported for the four mechanisms described earlier, ie, free radical, anionic, cationic, and Ziegler, several processes can be used. Table 6 summarizes the processes which have been used to implement each mechanism for Hquid-phase systems. Free-radical polymerization of styrenic systems, primarily in solution, is of principal commercial interest. Details of suspension processes, which are declining in importance, are available (208,209), as are descriptions of emulsion processes (210) and summaries of the historical development of styrene polymerization processes (208,211,212). 

Ethoxylation of alkyl amine ethoxylates is an economical route to obtain the variety of properties required by numerous and sometimes smaH-volume industrial uses of cationic surfactants. Commercial amine ethoxylates shown in Tables 27 and 28 are derived from linear alkyl amines, ahphatic /-alkyl amines, and rosin (dehydroabietyl) amines. Despite the variety of chemical stmctures, the amine ethoxylates tend to have similar properties. In general, they are yellow or amber Hquids or yellowish low melting soHds. Specific gravity at room temperature ranges from 0.9 to 1.15, and they are soluble in acidic media. Higher ethoxylation promotes solubiUty in neutral and alkaline media. The lower ethoxylates form insoluble salts with fatty acids and other anionic surfactants. Salts of higher ethoxylates are soluble, however. Oil solubiUty decreases with increasing ethylene oxide content but many ethoxylates with a fairly even hydrophilic—hydrophobic balance show appreciable oil solubiUty and are used as solutes in the oil phase. 

The development of micellar liquid chromatography and accumulation of numerous experimental data have given rise to the theory of chromatographic retention and optimization methods of mobile phase composition. This task has had some problems because the presence of micelles in mobile phase and its modification by organic solvent provides a great variety of solutes interactions. 

The corrosivity of solutions containing more than one acid may be unrepresentative of the corrosivity of either acid alone. Such mixtures are used widely in a variety of industrial applications. 

A catalyst is defined as a substance that influences the rate or the direction of a chemical reaction without being consumed. Homogeneous catalytic processes are where the catalyst is dissolved in a liquid reaction medium. The varieties of chemical species that may act as homogeneous catalysts include anions, cations, neutral species, enzymes, and association complexes. In acid-base catalysis, one step in the reaction mechanism consists of a proton transfer between the catalyst and the substrate. The protonated reactant species or intermediate further reacts with either another species in the solution or by a decomposition process. Table 1-1 shows typical reactions of an acid-base catalysis. An example of an acid-base catalysis in solution is hydrolysis of esters by acids. 

Reduction of the pH of solutions of carbonylate anions yields a variety of protonated species and, from acid solutions, carbonyl hydrides such as the unstable, gaseous H2Fe(CO)4 and the polymeric liquids H2Fe2(CO)g and H2Fe3(CO)n are liberated. The use of ligand-replacement reactions to yield hydrides of higher nuclearity has already been noted. 

A third motivation for studying gas solubilities in ILs is the potential to use compressed gases or supercritical fluids to separate species from an IL mixture. As an example, we have shown that it is possible to recover a wide variety of solutes from ILs by supercritical CO2 extraction [9]. An advantage of this technology is that the solutes can be removed quantitatively without any cross-contamination of the CO2 with the IL. Such separations should be possible with a wide variety of other compressed gases, such as C2LL6, C2LL4, and SF. Clearly, the phase behavior of the gas in question with the IL is important for this application. 

The n values were high for all of the ionic liquids investigated (0.97-1.28) when compared to molecular solvents. The n values result from measuring the ability of the solvent to induce a dipole in a variety of solute species, and they will incorporate the Coulombic interactions from the ions as well as dipole-dipole and polarizability effects. This explains the consistently high values for all of the salts in the studies. The values for quaternary ammonium salts are lower than those for the monoalkylammonium salts. This probably arises from the ability of the charge center on the cation to approach the solute more closely for the monoalkylammonium salts. The values for the imidazolium salts are lower still, probably reflecting the delocalization of the charge in the cation. 

Flammable liquids are widely used in many types of factories, and their misuse is responsible for many outbreaks of fire. The fire risks from the flammable liquids in common use such as petrol, paraffin, white spirit, cellulose solutions and thinners are well known, but these are only a few of the liquids which present hazards in industry. The variety of flammable liquids used in processes as solvents or carriers and for other purposes is constantly extending. 

Unfortunately, there is no general theory that will explain all the forms of localised attack that occur with the variety of metal/environment systems encountered in practice, e.g. the mechanism of the pitting of stainless steels in Cl -containing solutions is quite different from the dezincification of brass in a fresh natural water. Nevertheless, many of the following factors play an important part in most forms of localised attack ... 

The passivity at pH values above about 1 5 is maintained in a great variety of solutions, including fruit juices, vinegar, sea-water, alkalis, and even ferric chloride. Hot caustic alkali solutions above about 10% attack the coating slowly, and the halogens etch it. 

Hence, Flory s theory offers an objective criterion for chain flexibility and makes possible to divide all the variety of macromolecules into flexible-chain (f > 0.63) and rigid-chain (f < 0.63) ones. In the absence of kinetic hindrance, all rigid-chain polymers must form a thermodynamically stable organized nematic phase at some polymer concentration in solution which increases with f. At f > 0.63, the macromolecules cannot spontaneously adopt a state of parallel order under any conditions. 

The most common way to generate sulfonyl radicals for spectroscopic studies has been the photolysis of solutions containing di-t-butyl peroxide, triethylsilane and the corresponding sulfonyl chloride in a variety of solvents (equations 4-6). The slowest step in this sequence is the reaction between t-butoxyl radicals and triethylsilane (ks = 5.3 x 106m 1s-1)26 since that for chlorine abstraction (equation 6) is extremely efficient (cf. Table 4). 

There are several techniques now at our disposal for obtaining this fundamental biophysical information about solutions of polysaccharides (Table 1 [2-7]), but as is well known these substances are by no means easy to characterise. These difficulties arise from their highly expanded nature in solution, their polydispersity, (not only with respect to their molecular weight but also for many with respect to composition), the large variety of conformation and in many cases their high charge and in some their ability to stick together [1,8]. All of these features can complicate considerably the interpretation of solution data. 

---