Inert chemicals

Wood While fairly inert chemically, wood is readily dehydrated by concentrated solutions and hence shrinks badly when subjected to the action of such solutions. It is also slowly hydrolvzed by acids and alkalies, especially when hot. In tank construction, if sufficient shrinkage once takes place to allow ctystals to form between the staves, it becomes very difficult to make the tank tight again. 

A crystalline form of free silica, extremely hard and inert chemically very resistant to heat. Quartz in refractory bricks and amorphous silica in diatomaceous earth are altered to cristobalite when exposed to high temperatures (calcined). Cristobalite is extensively used in precision casting by the hot wax process, dental laboratory work, and certain speciality ceramics. 

Fillers may be broadly defined as solid particulates or fibrous materials, substantially inert chemically, incorporated in polymer compositions to modify the properties and/or to reduce cost. Cost reduction is not the primary reason to incorporate fillers in adhesives but they are used to impart specific properties such as flow, improved adhesion, mechanical, thermal, electrical and optical properties, chemical and weather resistance, and rheological behaviour. 

The most important nitride of Si is Si3N4 this is formed by direct reaction of the elements above 1300 or more economically by heating Si02 and coke in a stream of N2/H2 at 1500". The compound is of considerable interest as an engineering material since it is almost completely inert chemically, and retains its strength, shape and resistance to corrosion and wear even above 1000°. ° Its great hardness (Mohs 9), high... 

Tungsten bronzes can be prepared by a variety of reductive techniques but probably the most general method consists of heating the normal tungstate with tungsten metal. They are extremely inert chemically, being resistant both to alkalis and to acids, even when hot and concentrated. Their colours depend in the proportion of M and W present. In the case of sodium... 

Fluorocarbons (PTFE, FEP, PVF2) Powder, emulsions Excellent high temperature properties. TFE to 500 F. FEP is easier to mold, but maximum use temperature is 400 F. Nearly inert chemically. Nonflammable. Loading with conductive filler improves creep resistance. Low coefficient of friction. High-temperature cable shielding, gaskets, heat-shrinkable tubing. 

The nature of the Debye-Hiickel equation is that the activity coefficient of a salt depends only on the charges and the ionic strength. The effects, at least in the limit of low ionic strengths, are independent of the chemical identities of the constituents. Thus, one could use N(CH3)4C1, FeS04, or any strong electrolyte for this purpose. Actually, the best choices are those that will be inert chemically and least likely to engage in ionic associations. Therefore, monovalent ions are preferred. Anions like CFjSO, CIO, /7-CIC6H4SO3 are usually chosen, accompanied by alkali metal or similar cations. 

Semiconductor properties are imparted by doping its structure with boron, phosphorus, or arsenic atoms. Silicon is relatively inert chemically but is attacked by halogens and dilute alkalies. It has good optical transmission especially in the infra-red. 

Some attempts have been made to use reactive hydrocarbons in conjunction with inert chemical tracers to deduce HO concentrations in urban plumes (139,140,141). Difficulties in deducing [HO ] from these experiments have been studied by McKeen et al (142), who conclude that such experiments can underpredict HO concentrations by a factor of 2 when more reactive hydrocarbons are used and parameterization of transport processes is not properly accounted for. 

Compared with tar, which has a relatively short lifetime in the marine environment, the residence times of plastic, glass and non-corrodible metallic debris are indefinite. Most plastic articles are fabricated from polyethylene, polystyrene or polyvinyl chloride. With molecular weights ranging to over 500,000, the only chemical reactivity of these polymers is derived from any residual unsaturation and, therefore, they are essentially inert chemically and photochemically. Further, since indigenous microflora lack the enzyme systems necessary to degrade most of these polymers, articles manufactured from them are highly resistant or virtually immune to biodegradation. That is, the properties that render plastics so durable... 

Solubility/miscibility Insoluble in ethanol. Soluble to twice its weight (2 x grams) in water (xml). Soluble in glycerol and propylene glycol Biological considerations Virtually biologically inert Chemical compatibility/Stability considerations None Uses (routes) Orally, as diluent or viscosity increaser in solvents... 

Waxes are esters of fatty acids with long chain primary alcohols (Figure 12.2). The fatty acid is usually straight chain which may be saturated or mono-unsat-urated although occasionally branched chain or hydroxy acids are found. They are extremely non-polar compounds and are relatively inert chemically but they can be hydrolysed using a strong alkali, such as potassium hydroxide, a process called saponification. 

The unique problem that arises here is that Fll and F12 are relatively inert chemically and have no natural sources or sinks, as CCI4 does. The lifetimes of these fluorocarbons are controlled by diffusion to the stratosphere, where ... 

Although Pt02 is rather inert chemically, its presence causes many problems. First, it represents part of a redox couple in the presence of Pt (albeit a rather irreversible couple), which itself causes errors, particularly during potentiometric... 

Ethers are volatile and highly flammable. They are used as solvents because they are relatively inert chemically and most organic compounds dissolve in them. Being volatile, these solvents are easily removed by distillation. 

Including in the medication a biological marker that is non-toxic, inert, chemically stable and easily detectable in biological fluids (such markers include riboflavin, phenol red and small quantities of digoxin). 

Due to the pyramidalization of the C atoms and the rigid cage structure of Cjq the outer convex surface is very reactive towards addition reactions but at the same time the inner concave surface is inert (chemical Faraday cage). This allows the encapsulation, observation and tuning of the wavefimction of extremely reactive species that otherwise would immediately form covalent bonds with the outer surface. 

The system consists of a preformed dye joined to a photographic developer moiety (hydroqninone) by an inert chemical link, e.g. so that they move together... 

The apparent order of Vp with respect to hydrocarbon depends somewhat on the solvent, as shown in Figure 1. In fert-butylbenzene, which is inert chemically and clearly resembles the xylenes, Vp is first order in hydrocarbon, but deviations occur in o-dichlorobenzene. This principle affects generally the choice of solvents (21). Thus, even in radical oxidation, where solvent effects are much weaker than in ionic reactions, proper choice of solvent is essential if kinetic laws are to be observed over a wide range of reagent concentrations. 

Shortly thereafter, Molina and Rowland (1974) published their seminal paper in which they showed that, because of the lack of removal mechanisms for these inert chemicals in the troposphere, chlorofluorocarbons (CFCs) are expected to reach the stratosphere. Once in the stratosphere, the CFCs are exposed to UV radiation in the region in which they absorb, leading to the production of chlorine atoms ... 

Metabolic Activation The biotransformation (q.v.) of relatively inert chemicals to biologically reactive metabolites. 

Comparing the three substrates that were plasma-coated in this study, it has become clear that silica is very easy to encapsulate with a plasma coating, whereas carbon black is difficult to treat because of its inert chemical surface structure. Sulfur is also more difficult to handle, but in this case the incomplete coating is an advantage because the sulfur has to be released from the encapsulation shell in order to be efficient as curing agent. In all cases, the polarity of the substrate is reduced. 

In the discussion thus far, the application of systems with completely mobile components has been restricted to bed-rock weathering, sedimentation and free-flowing aquifer environments. As a first approximation in other geological situations, clay mineral suites can be adequately described using "inert" chemical components, i.e., those which are extensive variables of the system, and by using pressure-temperature as intensive variables. Hydrothermal alteration is, in contrast, an environment where many chemical components can be treated as being completely... 

In 1842, T. Andrews1 pointed out that although moist chlorine combines energetically with zinc, copper, and iron-filings, perfectly dry chlorine has no action whatever at ordinary temp.,. . . and the same remarks may be applied to the behaviour of dry bromine in contact with dry metals. Indeed, thoroughly dry chlorine is somewhat inert chemically, and it has no appreciable action upon bright metallic sodium, copper, etc. Dried chlorine scarcely acts at all upon, dry silver ... 

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