Acids, bases and solvents

The clear, colorless coating resists graffiti, marine-fouling organisms, solvents, acids, bases, and sodium chloride. It can also be used as a mold-release and ice-release coating. 

Source containers must be sufficiently rigid to maintain their shape. They must resist attack and decomposition from contents such as organic solvents, acids, bases, and biological material. They must be closed to prevent spillage, permit storage, and protect the detector and its environment from contaminants. In some... 

This chapter describes the general effects of chemicals on plastics and elastomers (elastomers) which will be referred to as polymers for brevity purposes. Even metals are not immune from attack by chemicals. Water corrodes iron, acids dissolve many metals. There is, however, a perception that metals are by and large not attacked by a large number of chemicals, starting with organic solvents. This perception is basically correct, but it does not apply to plastics. Solvents, acids, bases and other chemicals affect the overwhelming majority of polymers. 

These kinds of stores carry hobby/craft supplies, gimmicky science fair projects, ant farms and a low assortment of basic scienceware products such as beakers, thermometers, scales, rubber stoppers and most of the basic chemicals such as acids, bases and solvents. These places are listed in the chemicals section of any big city s yellow pages and are relatively safe places to get most of the basic lab necessities. The drawback is that they are really expensive and don t sell very large quantities of any chemical. It is possible to have these places special order a needed chemical as long as it s not a controlled chemical. 

In a simple liquid-liquid extraction the solute is partitioned between two immiscible phases. In most cases one of the phases is aqueous, and the other phase is an organic solvent such as diethyl ether or chloroform. Because the phases are immiscible, they form two layers, with the denser phase on the bottom. The solute is initially present in one phase, but after extraction it is present in both phases. The efficiency of a liquid-liquid extraction is determined by the equilibrium constant for the solute s partitioning between the two phases. Extraction efficiency is also influenced by any secondary reactions involving the solute. Examples of secondary reactions include acid-base and complexation equilibria. 

Potcntiomctric Titrations In Chapter 9 we noted that one method for determining the equivalence point of an acid-base titration is to follow the change in pH with a pH electrode. The potentiometric determination of equivalence points is feasible for acid-base, complexation, redox, and precipitation titrations, as well as for titrations in aqueous and nonaqueous solvents. Acid-base, complexation, and precipitation potentiometric titrations are usually monitored with an ion-selective electrode that is selective for the analyte, although an electrode that is selective for the titrant or a reaction product also can be used. A redox electrode, such as a Pt wire, and a reference electrode are used for potentiometric redox titrations. More details about potentiometric titrations are found in Chapter 9. 

Ethers are unreactive to many reagents used in organic chemistry, a property that accounts for their wide use as reaction solvents. Halogens, dilute acids, bases, and nucleophiles have no effect on most ethers. In fact, ethers undergo only one reaction of general use—they are cleaved by strong acids. Aqueous HBr and HI both work well, but HCl does not cleave ethers. 

Acids, bases, and salts (i.e., electrolytes in the second sense of the word) dissociate into ions when dissolved in water (or in other solvents). This dissociation can be complete or partial. The fraction of the original molecules that have dissociated is known as the degree of dissociation, a. Substances that exhibit a low degree of dissociation in solution are called weak electrolytes, whereas when the value of a comes close to unity we speak of strong electrolytes. 

Inorganic solvents (acids, bases, salt solutions, mixtures of acids bases, and their salts). 

Introduction of the flushing solution may occur within the vadose zone, the saturated zone, or both. Flushing solutions may consist of plain water, or surfactants, co-solvents, acids, bases, oxidants, chelants, and solvents. The infiltrating flushing solution percolates through the soil and soluble compounds present in the soil are dissolved. The elutriate is pumped from the bottom of the contaminated zone into a water treatment system to remove pollutants. The process is carried out until the residual concentrations of contaminants in the soil satisfy given limits. 

Dissolving the test sample by water, other solvents, acids, bases, melts, and gases... 

A mechanistic study of acetophenone keto-enol tautomerism has been reported, and intramolecular and external factors determining the enol-enol equilibria in the cw-enol forms of 1,3-dicarbonyl compounds have been analysed. The effects of substituents, solvents, concentration, and temperature on the tautomerization of ethyl 3-oxobutyrate and its 2-alkyl derivatives have been studied, and the keto-enol tautomerism of mono-substituted phenylpyruvic acids has been investigated. Equilibrium constants have been measured for the keto-enol tautomers of 2-, 3- and 4-phenylacetylpyridines in aqueous solution. A procedure has been developed for the acylation of phosphoryl- and thiophosphoryl-acetonitriles under phase-transfer catalysis conditions, and the keto-enol tautomerism of the resulting phosphoryl(thiophosphoryl)-substituted acylacetonitriles has been studied. The equilibrium (388) (389) has been catalysed by acid, base and by iron(III). Whereas... 

PMMA is resistant to nonoxidizing acids, bases, and salts at ordinary temperatures but is attacked by oxidizing acids at room temperature. It is resistant to highly polar solvents, such as ethanol, but is soluble in less polar solvents, such as toluene. 

Solvent extraction of the sample is also frequently used in the analysis of particulate matter. Through the appropriate choice of solvents, the organics can be separated into acid, base, and neutral fractions, polar and nonpolar fractions, and so on. This grouping of compounds according to their chemical properties using extraction techniques simplifies the subsequent analysis. Each fraction can then be analyzed by GC-MS, with the GC retention time and the mass spectrum used for identification and measurement. 

It is a system of acids, bases and salts with liquid ammonia as solvent instead of water. Thus the water system ... 

Tetracycline antibiotics are closely related derivatives of the polycyclic naphtha-cenecarboxamide. They are amphoteric compounds with characteristic dissociation constants corresponding to the acidic hydroxyl group at position 3 (pK about 3.3), die dimethylamino group at position 4 (pK, about 7.5), and the hydroxyl group at position 12 (pK about 9.4). In aqueous solutions of pH 4-7, tetracyclines exist as dipolar ions, but as the pH increases to 8-9 marked dissociation of the dimethylamine cation occurs. They are soluble in acids, bases, and alcohols but are quite insoluble in organic solvents such as chloroform. Their ultraviolet spectra show strong absorption at around 270 and 360 nm in neutral and acidic solutions. Tetracyclines are readily transformed into fluorescent products in the presence of metal ions or under alkaline conditions. 

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