Amalgams chemical composition

All the above studies indicated clearly that reduction of solvent, salt, and additives (e.g., H20) by Li contribute together to the buildup of the surface films on lithium in solutions. It should be emphasized that XRD, XPS, and AES studies of Li electrodes, as well as the indirect identification of surface species from studies of reactions of lithiated graphite or Li/Hg amalgam with electrolyte solutions, could not provide specific enough information on the chemical composition of the surface films. Moreover, application of XPS for Li electrodes may induce secondary surface reactions. Visible changes appear on Li surfaces during XPS measurements. More specific information on the composition of the surface layers formed on Li could be obtained by surface-sensitive FTIR spectroscopy that was introduced into this field in the middle of 1985 by Yeager et al. [84,85,178], and which is a nondestructive technique. 

Electrochemical potentials can arise from differences in electrolyte or electrode concentration as well as from differences in chemical composition. Thus, for example, there will be a difference in potential between two amalgam or alloy electrodes of the same basic type in which there is a difference in the activity of one of the alloy or amalgam constituents. The practical implication is that galvanic corrosion can occur between similar alloys of different composition. Crevice corrosion phenomena are often explainable in terms of differences in oxygen concentration. 

ReCl3(PPh3)(benzil)] reacts with bipy and related ligands or terpy to form a number of rhe-nium(III) and rhenium(II) compounds which are useful precursors for the synthesis of lower-valent rhenium complexes. " Thus, reduction of [Re(bipy)3][PF6]2 with zinc amalgam results in the rhenium(I) compound [Re(bipy)3][PF6] in excellent yields. The corresponding terpyridyl bis-chelate [Re(terpy)2][PF6] has been prepared in a similar manner. " The electrochemistry of the products provides a convenient measure of the chemical reactivity associated with the redox processes. Thus, the one-electron oxidation of [Re(bipy)3]" is reversible at -0.33 V, whereas the Re"/Re" redox couple is irreversible and occurs at relatively low potentials (-1-0.61 V) which is consistent with the instability of [Re(bipy)3] + in solution. However, in the presence of a small coordinating molecule such as CNBu, oxidation to the rhenium(III) state is readily available by the formation of seven-coordinate complexes of the composition [Re(bipy)3(L)]. " ... 

By running a potentiometric precipitation titration, we can determine both the compositions of the precipitate and its solubility product. Various cation- and anion-selective electrodes as well as metal (or metal amalgam) electrodes work as indicator electrodes. For example, Coetzee and Martin [23] determined the solubility products of metal fluorides in AN, using a fluoride ion-selective LaF3 single-crystal membrane electrode. Nakamura et al. [2] also determined the solubility product of sodium fluoride in AN and PC, using a fluoride ion-sensitive polymer membrane electrode, which was prepared by chemically bonding the phthalocyanin cobalt complex to polyacrylamide (PAA). The polymer membrane electrode was durable and responded in Nernstian ways to F and CN in solvents like AN and PC. 

An alloy is a solution of two or more metals. Amalgams are alloys which involve mercury as one component. A silver amalgam as used in dental work is a solution of silver and mercury. The pewter used to make silverware in Revolutionary War times is an alloy with the composition 85.5% tin, 6.8% copper, 6% bismuth, and 1.7% antimony. Most alloys usually have Physical properties which are different from those of the individual components. In contrast, the chemical properties of the alloy are related to those of the individual components. 

Biomaterials in general are based on the materials groups metals, polymers and ceramics [3]. Typical metallic biomaterials are based on stainless steel, cobolt based alloys and titanium or titanium alloys and amalgam alloys. Polymeric biomaterial composites from monomers are based on amides, ethylene, propylene, styrene, methacrylates, and/or methyl methacrylates. Biomaterials based on ceramics are found within aU the classical ceramic families traditional ceramics, special ceramics, glasses, glass-ceramics, coatings and chemically bonded ceramics (CBC). 

Dental amalgam, consisting of mercury alloyed with another element, is still approved for use in most countries, but conflicting views have been expressed over the use of mercury as filling material. Some dentists are still recommending the use of dental amalgam with mercury because of its durability, ease of use, and low cost compared to resin composites (for which concerns have been raised due to the presence of plastic chemicals such as Bisphenol A, well known for its endocrine disruptor effects) and dental porcelain. However, it is believed that leaching of mercury into the mouth and consequential health effects related to mercury toxicity (such as risk of impairment in the central nervous system function, kidney function, immune system, and fetal development) are associated with mercury exposure. 

---