Universal solvent

In the early part of the twentieth century, benzene was used as a universal solvent and degreaser and found widespread use throughout the mbber iadustry iu the manufacture of tires. By the late 1920s, foUowiug reports of deaths due to benzene exposure, it was largely replaced by toluene and ahphatic solvents (131). 

Returning now to the subject of the chapter, in addition to appropriate retentive characteristics, a potential stationary phase must have other key physical characteristics before it can be considered suitable for use in LC. It is extremely important that the stationary phase is completely insoluble (or virtually so) in all solvents that are likely to be used as a mobile phase. Furthermore, it must be insensitive to changes in pH and be capable of assuming the range of interactive characteristics that are necessary for the retention of all types of solutes. In addition, the material must be available as solid particles a few microns in diameter, so that it can be packed into a column and at the same time be mechanically strong enough to sustain bed pressures of 6,000 p.s.i. or more. It is clear that the need for versatile interactive characteristics, virtually universal solvent insolubility together with other critical physical characteristics severely restricts the choice of materials suitable for LC stationary phases. 

The existence of strongly polar water molecules and mobile protons also makes H2O an excellent and almost universal solvent for ionic... 

One of the most important problems of planar chromatography is that of the optimization of solvent systems for the separation of mixtures of different samples. An analyst is interested in obtaining the expected result using a minimum number of experiments. Snyder has introduced a new system for solvent classification that permits a logical selection of solvents both in term of polarity indices (F ) and selectivity parameters (Xj), proving theoretically the validity of such universal solvent systems [18,38,41,42]. 

The following is a partial list of the properties of water. Classify the properties as chemical or physical acts as a universal solvent, has high boiling point, exhibits high specific heat capacity, has density of about lg/mL, has a pH that is neutral, has no odor, is colorless. 

Many of the reactions that you will study occur in aqueous solution. Water is called the universal solvent, because it dissolves so many substances. It readily dissolves ionic compounds as well as polar covalent compounds, because of its polar nature. Ionic compounds that dissolve in water (dissociate) form electrolyte solutions, which conduct electrical current owing to the presence of ions. The ions can attract the polar water molecules and form a bound layer of water molecules around themselves. This process is called solvation. Refer to the Solutions and Periodicity chapter for an in-depth discussion of solvation. 

Water is the universal solvent, dissolving a wide variety of both ionic and polar substances. 

Trimpin, S. Rouhanipour, A. Az, R. Rader, H.J. Mullen, K. New Aspects in MALDI-TOF-MS a Universal Solvent-Free Sample Preparation. Rapid Commun. Mass Spectrom. 2001,15, 1364-1373. 

Water is called the universal solvent because of its ability to dissolve at least a little of virtually every substance. Water is a particularly good solvent for substances held together by polar or ionic bonds. Indeed, the most abundant substance dissolved in seawater is an ionic solid, sodium chloride. In comparison, only small amounts of nonpolar substances, such as hydrocarbon oils, will dissolve in water. 

Because water is a universal solvent, at least some of virtually every element is present as a solute in seawater. As shown in Table 3.1, the most abundant substances in seawater are the major ions (Cl , Na", SO4 , Mg ", Ca ", and K" ). They are present in nearly constant proportions in the open ocean because their concentrations are largely controlled by physical processes associated with water movement, such as transport by currents, mixing via turbulence, evaporation, and rainfall. These solutes are also referred to as conservative ions. Most of the rest of the solutes in seawater are not present in constant proportions because their concentrations are altered by chemical reactions that occur faster than the physical processes responsible for water movement. These chemicals are said to be nonconservative. Though most substances in seawater are nonconservative, they collectively comprise only a small fraction of the total mass of solutes and solids in the ocean. 

Universal solvent Water, which is so named due to its ability to dissolve at least a small amount of aU substances. 

There is no universal solvent, and solvent selection must be made individually for each separation problem. The specific choice must be based on a general knowledge of the different interactions in both phases. Among the desirable features for the extracting solvent are the following ... 

Water is often called the universal solvent . The primary reason that water is such a good solvent is due to... 

When water, the universal solvent, is present on a planet, an asteroid, or in a meteorite, a wide variety of chemical reactions take place that can completely alter the mineralogy and chemistry of an object. Some meteorites show extensive evidence of aqueous alteration. To understand the conditions under which the alteration occurred, one must be able to infer the amount, composition, and temperature of the fluids from the minerals that they produced. 

Water is often referred to as the universal solvent, but the expression oil and water don t mix defies this label. Many substances dissolve in water to varying degrees. It is an excellent... 

Methylene chloride was selected primarily on the basis of the following criteria (1) It is commonly referred to as the universal solvent or the one used most frequently in the extraction of semivolatile organics sorbed on polymeric sorbent media. Hence, the contaminant chemistry associated with this solvent system would be of the most use to resin users. (2) The physical and chemical properties of methylene chloride make it ideally suited for the extraction of semivolatile organics sorbed on polymeric sorbent media. 

There is no universal solvent, and even for a given application one rarely finds an ideal system. One must factor some informed guesswork into one s choice of solvent and electrolyte. In order to optimize conditions for an electrode reaction, one must consider how its chemical and electrochemical features, for... 

Water is a universal solvent, and as a result all sources of water used for domestic and industrial purposes contain various concentrations of dissolved minerals and gases, in addition to suspended solids and biological matter. The relative amounts of each of these impurities tend to vary considerably with geographic location and season, resulting in countless permutations of water type and quality around the world potentially available for use as makeup to cooling systems. As a precursor to looking at these sources of water, a recap of some fundamentals of water chemistry relevant to our purpose is provided here. 

The chemical composition of any water is generally directly related to the geological area from which it is sourced, the universal solvent effect. 

Non DLVO forces in water deserve a special subchapter because they are important and far from being understood. They are important because water is the universal solvent in nature. Also, in more and more industrial processes water is used instead of organic solvent since it is harmless to the environment. 

Dimethylsulfoxide (DMSO), the archetypal penetration enhancer, is a powerful aprotic solvent that is colorless, odorless, and hygroscopic its value as an enhancer may be predicted from its use chemically as a universal solvent (Figure 12.2). 

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