Displacement chemical

The range of chemical displacement is much wider (200 ppm as opposed to 15). 

For articles that require only a very thin film of tin, seldom exceeding 0.8 p.m immersion tin coatings are appHed. The process is based on chemical displacement by immersion in a solution of tin salts. Recently, a new autocatalytic tin-deposition process was developed at the research level. It promises to be useful to coat any base material including plastics, in addition to providing coatings of any thickness desired (21). 

The metallic impurities present in an impure metal can be broadly divided into two groups those nobler (less electronegative) and those less noble or baser (more electronegative) as compared to the metal to be purified. Purification with respect to these two classes of impurities occurs due to the chemical and the electrochemical reactions that take place at the anode and at the cathode. At the anode, the impurities which are baser than the metal to be purified would go into solution by chemical displacement and by electrochemical reactions whereas the nobler impurities would remain behind as sludges. At the cathode, the baser impurities would not get electrolytically deposited because of the unfavorable electrode potential and the concentration of these impurities would build up in the electrolyte. If, however, the baser impurities enter the cell via the electrolyte or from the construction materials of the cell, there would be no accumulation or build up because these would readily co-deposit at the cathode and contaminate the metal. It is for this reason that it is extremely important to select the electrolyte and the construction materials of the cell carefully. In actual practice, some of the baser impurities do get transferred to the cathode due to chemical reactions. As an example, let the case of the electrorefining of vanadium in a molten electrolyte composed of sodium chloride-potassium chloride-vanadium dichloride be considered. Aluminum and iron are typically considered as baser and nobler impurities in the metal. When the impure metal is brought into contact with the molten electrolyte, the following reaction occurs... 

B. N.M.R. Spectra of Proton Addition Complexes 1. Chemical displacement in proton addition complexes... 

Iodine, iron, and zinc increased in wells over the concentrations in the brine or local groundwater, represented by the private (PVT) well. The researchers hypothesized that chemical displacement of ions coating the sand grains took place. This explanation is plausible for the iron alone. Hence, another explanation was... 

Nearly all the experiments described were performed in an ultra high vacuum chamber at pressures of about 10 10 torr. The specific equipment and experimental procedures used have been described elsewhere (7-9). Experimental protocol for the thermal desorption experiments and for the chemical displacement reactions is presented below. All these experiments were repeated with a control, blank experiment with a metal crystal that had the front and exposed face covered with gold the sides and back of the crystal were exposed (8,9). These blank experiments were performed to ensure that all thermal desorption and chemical displacement experiments monitored only the surface chemistry of the front exposed face of the metal crystal under study. 

One of the first approaches of analyte-mediated changes in the surface of QDs has been reported by He and coworkers. They used CdSe QDs modified with mercaptoacetic acid for the selective determination of Ag+. The changes in the emission properties of the QDs were attributed to the chemical displacement of Cd + by Ag+ in the outermost cluster atom layers of the QDs with subsequent formation of Ag2Se. In an analogous way, mercaptoethanol-capped CdSe/CdS QDs were utilized for the detection of Cu " through the displacement of Cd " " and formation of... 

Unfortunately, the HF laser, which is the shortest wavelengdi vibrational laser possible, operates at about 2.7 microns. Extension to visible wavelengths will require transitions between electronic energy levels. The relative simplicity and notable success of vibrational lasers led to the pursuit of visible wavelen lasers based upon simple chemical displacement processes similar to reaction (1), and early investigations used this approacl Before we discuss these early studies, it is... 

The removal of a metal M from solution by chemical displacement it, cementation of a metal onto a more base metal M substrate) is widely used in hydrometallurgy ... 

Driving force Power supply Autocatalytic redox reaction Chemical displacement... 

The perturbation can be simple or produced periodically, and in the latter case, according to the frequency and the rate of the reaction, the chemical displacement will follow exactly or with a certain time lag the perturbation. 

The halogen in 1-chloronaphthalene and 9-bromophenanthrene is photo-chemically displaced by PhSe" in liquid ammonia - probably by an 5rn1 process. ... 

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