Gold-bismuth compounds

Many metal complexes have been shown to possess bioactivity and several drugs based on metal complexes have been developed. These include platinum, gold, and bismuth compounds used in the treatment of certain kinds of cancer, arthritis, and stomach ailments, respectively [82]. The development of analogous polymeric chemotherapeutic materials, that would less easily diffuse through membranes, is also an important objective. 

It is applied to the ware as a suspension of gold powder in essential oils, with or without the addition of a proportion of BRIGHT GOLD (q.v.) Other ingredients are a flux (e.g. lead borosilicate or a bismuth compound) to promote adhesion to the ware, and an extender such as a mercury salt. This type of gold decoration is dull as taken from the kiln, hence the need for subsequent burnishing, cf. acid... 

The pyrometaHurgical processes, ie, furnace-kettle refining, are based on (/) the higher oxidation potentials of the impurities such as antimony, arsenic, and tin, ia comparison to that of lead and (2) the formation of iasoluble iatermetaUic compounds by reaction of metallic reagents such as 2iac with the impurities, gold, silver and copper, and calcium and magnesium with bismuth (Fig. 12). 

Metals less noble than copper, such as iron, nickel, and lead, dissolve from the anode. The lead precipitates as lead sulfate in the slimes. Other impurities such as arsenic, antimony, and bismuth remain partiy as insoluble compounds in the slimes and partiy as soluble complexes in the electrolyte. Precious metals, such as gold and silver, remain as metals in the anode slimes. The bulk of the slimes consist of particles of copper falling from the anode, and insoluble sulfides, selenides, or teUurides. These slimes are processed further for the recovery of the various constituents. Metals less noble than copper do not deposit but accumulate in solution. This requires periodic purification of the electrolyte to remove nickel sulfate, arsenic, and other impurities. 

Rubidium metal alloys with the other alkaU metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double haUde salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and 2iac. These complexes are generally water iasoluble and not hygroscopic. The soluble mbidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide. 

Nine elements were known in ancient times gold, silver, iron, mercury, tin, copper, lead, carbon, and sulfur. Bismuth, zinc, antimony, and arsenic were isolated in the alchemical period and Middle Ages. It was known that certain substances combined into other substances before the modern idea of elements and compounds was established. In 1718, Etienne Francois Geoffioy (1672—1731) presented a Table of Affinities to the French Academy of Science that summarized which substances were compatible with each other and combined to produce other substances (Figure 1.2). 

Ferric salts are reduced to the ferrous condition and chromates are reduced to chromic salts. Salts of gold, silver, copper, antimony, bismuth and mercury are reduced to the free metals, which are frequently obtained as colloidal solutions if the original solutions are weak with the exception of the first-named there is a tendency for the liberated metal to be accompanied by sulphide, especially if excess of hydrosulphite is used.7 Chloroplatinic acid is reduced to red chloroplatinous acid solution. Tellurous and telluric acids, selenious acid and arsenic compounds, are reduced to the free elements.8... 

Write the chemical formulas for (a) gold(III) nitrate, cobalt(II) nitrate, bismuth(V) nitrate, radium nitrate, tin(IV) nitrate, and arsenic(III) nitrate, (b) Write the sulfite compounds. 

Other metals, such as copper, nickel, or silver, have been used as electrode materials in connection with specific applications, such as the detection of amino acids or carbohydrates in alkaline media (copper and nickel) and cyanide or sulfur compounds (silver). Unlike platinum or gold electrodes, these electrodes offer a stable response for carbohydrates at constant potentials, through the formation of high-valence oxyhydroxide species formed in situ on the surface and believed to act as redox mediators (40,41). Bismuth film electrodes (preplated or in situ plated ones) have been shown to be an attractive alternative to mercury films used for stripping voltammetry of trace metals (42,43). Alloy electrodes (e.g., platinum-ruthenium, nickel-titanium) are also being used for addressing adsorption or corrosion effects of one of their components. The bifunctional catalytic mechanism of alloy electrodes (such as Pt-Ru or Pt-Sn ones) has been particularly useful for fuel cell applications (44). 

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