Pure/impure

Colorless to brown liquid that is odorless when pure impurities may give a faintly fruity or bitter almonds odor. Undergoes considerable decomposition when explosively disseminated. 

White to cream-white powder or crystalline material. Odorless when pure, impurities may give it a slight vinegar odor. This material is hazardous through inhalation, skin absorption, and ingestion, and produces local skin/eye impacts. 

Odor No odor when pure impurities cause odor of rotting fruit or bitter almonds... 

Fibrous sulfur is probably rarely pure. Impurities can influence the structure in many ways. As long as only mixtures are available, further, apparently contradictory reports on similar structures are to be expected. We discuss some of these forms in Section III. 

Gas chromatographic analysis (capillary column coated with thermon-1000, 30 m, 140 C) indicated that the product was ca. 93% pure. Impurities consisted of the 2E,4E isomer (5%) and an unidentified compound (2%). ... 

In previous chapters, we dealt with various electrochemical processes in non-aque-ous solutions, by paying attention to solvent effects on them. Many electrochemical reactions that are not possible in aqueous solutions become possible by use of suitable non-aqueous or mixed solvents. However, in order for the solvents to display their advantages, they must be sufficiently pure. Impurities in the solvents often have a negative influence. Usually commercially available solvents are classified into several grades of purity. Some of the highest-grade solvents are pure enough for immediate use, but all others need purification before use. In this chapter, the effects of solvent impurities on electrochemical measurements are briefly reviewed in Section 10.1, popular methods used in solvent purification and tests of impurities are outlined in Sections 10.2 and 10.3, respectively, and, finally, practical purification procedures are described for 25 electrochemically important solvents in Section 10.4. 

Grade 80-85% pure. Impurities are sodium acetate, sodium amide, and sodium hydroxide. 

Properties of Min-U-Sil 30 from Pennsylvania Glass Sand Quartz, 99,7% pure, impurities (in ppm) I CjG, 230, AIjO, 1010, TiO2190, BET specific surface area 0.77 mVg, particle size 8.8 pm [87]. 

GB manufactured in the USA was at least 93% pure. Impurities may include diisopropyl methylphosphonate (DIMP), a stable byproduct of manufacture, and methylphosphonic difluoride. DIMP is usually present at 2-3% in isopropyl methylphosphonate waste and is present in sampling wells, both on and off the RMA (Rosenblatt et al., 1995 Aulerich et al, 1979). In 1974, DIMP concentrations of 0.5 pg/1 (the limit of detection) to 44000 pg/1 were found in the groundwater near the Arsenal (Robson, 1981). 

BROMINE CYANIDE (506-68-3) Able to polymerize. May be unstable unless dry and pure impure material decomposes rapidly and tends to explode. Reacts violently with acids, ammonia, amines, phosgene. Water contact produces hydrogen cyanide and hydrogen bromide. 

Pure silicon is then made super-pure (impurities <10-9 atom percent) by zone refining. In this process a rod of metal is heated near one end so that a cross-sectional wafer of molten silicon is produced. Since impurities are more soluble in the melt than they are in the solid they concentrate in the melt, and the melted zone is then caused to move slowly along the rod by moving the heat source. This carries impurities to the end. The process may be repeated. The impure end is then removed. 

AND IMPURITIES 4-chlorophenyl isocyanate. The technical product is 95% pure. Impurities are of low toxicological concern in terminal residues... 

MTBE is commercially produced by the reaction of isobutylene with methanol in the presence of an acidic ion-exchange resin as catalyst, usually in the liquid phase and at temperatures below 100°C. A typical catalyst is sulfonated styrene/divinylbenzene resin catalyst. Other solid acid catalysts such as bentonites are also effective and other novel catalysts have recently been discovered. Isobutylene is obtained from field butane by initial isomerization of n-butane to isobutane, followed by dehydrogenation to isobutylene. Commercial preparations of MTBE are 95.03 to 98.93% pure. Impurities are methanol (<0.43%), t-butyl alcohol (<0.80%), and diisobutylene (<0.25%). 

The adsorptive capacity of silica gel for the impurity in hydrogen has been related to the same capacity on the "pure impurity isotherm by a dimensionless factor defined as follows ... 

It is often difficuit to distinguish between thermai and thermo-chemicai degradation because poiymers are rarely chemicaiiy pure. Impurities and additives can react with the poiymeric matrix at sufficientiy high temperatures. 

The phase diagram for this system, as reported by Naumkin et al. (1970) and Savitskii et al. (1970) is shown in fig. 15. Savitskii et al. did not reveal the purity of their alloying materials but Naumkin et al. reported a 99.7 wt% purity for their lanthanum (impurities, reported in wt%, were 0.04 Ce, 0.07 each Pr and Nd and 0.012 Fe). Their scandium was reported to be 99.7 wt% pure (impurities included 0.11 wt% O). Their alloys were formed by arc-melting the metals under an atmosphere of purified helium. Below the solidus, the body-centered cubic yLa and jSSc form a solid solution. Two eutectoid transformations at about 750°C and 45 at% Sc and 233°C and 14at% Sc result in regions of two-phase immiscibility. 

Very dry, OH measured in ppb Very pure, impurities measured in ppb... 

The discussion so far has been with respect to pure crystals. In reality, most crystals are not pure. Impurities can substitute for host ions of electronegativity nearest their own. For example, in NaCl, Ca and O can occupy the cation and anion sites, respectively. In writing a defect incorporation reaction, the following simple bookkeeping operation can be of help ... 

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