Silver standards

Quantitative estimates of the concentration levels of these 16 elements could be obtained by using silver standards containing known amounts of the elements of interest. Two standards were prepared at Brookhaven National Laboratory. Although we have established that the elements in these standards are homogeneously distributed, we have not completed their calibrations. Moreover the standards were not useful for scandium, tin, and iridium. For these elements the concentrations were calculated relative to those of elements for which good standards were available, using nuclear cross-sections and decay constants from the literature (7). 

Combined neutron Howitzer and streak analyses of 125 one- and two-peso coins not only reveal the real gold content of these issues but help to establish the silver standard, which was probably aimed at 900 thousands fine (90% silver), a creditable alloy and better than the 800 thousands (80%) of the federal subsidiary coinage. It was therefore possible to estimate fairly closely the theoretical composition and value of the Zapatista silver coinage. 

A series of silver standards gave a linear calibration curve in flame atomic absorption with a slope of 807 meter units per ppm Ag in the standard. (The meter units are arbitrary numbers proportional to absorbance, and ppm refers to ig Ag/mL.) An unknown cyanide solution passed through the silver membrane gave a meter reading of 198 units. Find the molarity of CN in the unknown-... 

About one-eighth of the antimony disc was left free. When taking X-ray patterns, a silver standard was placed onto this part of the specimen. B.Ya. Pines and E.F. Chaikovskiy were able to obtain on one and the same X-ray pattern the following diffraction lines (220) for aluminium, (321)... 

Figure 14.10. Variation in Ag Ka intensity with mineralogical composition. A = low-Z matrix = high-Z matrix. The line is a calibration curve derived from silver standards prepared in a silica matrix. From P. G. Burkhalter, Anal. Chem., 43, 10 (1971), by permission of the publisher. Copyright 1971 by the American Chemical Society.

Table 10.6 Intensity Data Taken on Silver Standards...

Sterling silver (standard grade) P07931 92.5Ag-7.5Cu 25sM 30 B [iEH... 

TABLE E.8 Wrought Nickel-Silvers—Standard Designations for Wrought Nickel-Silver Alloys (Composition as Maximum % Unless Indicated as Range or Minimum)... 

There are two procedures for doing this. The first makes use of a metal probe coated with an emitter such as polonium or Am (around 1 mCi) and placed above the surface. The resulting air ionization makes the gap between the probe and the liquid sufficiently conducting that the potential difference can be measured by means of a high-impedance dc voltmeter that serves as a null indicator in a standard potentiometer circuit. A submerged reference electrode may be a silver-silver chloride electrode. One generally compares the potential of the film-covered surface with that of the film-free one [83, 84]. 

Addition of silver nitrate to a solution of a chloride in dilute nitric acid gives a white precipitate of silver chloride, AgCl, soluble in ammonia solution. This test may be used for gravimetric or volumetric estimation of chloride the silver chloride can be filtered off, dried and weighed, or the chloride titrated with standard silver nitrate using potassium chromate(VI) or fluorescein as indicator. 

Figure 3-1 Voltage Measurements on a Silver-Silver Chloride, Hydrogen Cell at 298.15 K. The contribution of the Standard Hydrogen Electrode is taken as zero by convention.

The two estimates for the first or a parameter of the parabolic fit are the intercepts on the voltage axis of Eig. 3-1, so both procedures arrive at a standard potential of the silver-silver chloride half-cell of 0.2225 V. The accepted modem value is 0.2223 V (Barrow, 1996). 

The cyanide content may be determined by titration with standard silver nitrate solution. ... 

The method is generally applicable when other modes of esterification are either slow, inefficient, or likely to cause isomerisation it is, however, time-consuming and expensive. Small quantities of acid impurities are sometimes produced, hence it is advisable to wash the ester with saturated sodium bicarbonate solution. The silver salt can usually be prepared by dissolving the acid in the calculated quantity of standard ammonium hydroxide solution and... 

Nitroethane and 1-(3,4 methylenedioxy) 2- nitropropane This method of producing the above mentioned nitro compounds is by far the best Ritter has come across yet The problem with standard nitroethane synthesis is that the -NO2 source most commonly used is silver nitrite (a la Merck Index citing). Needless to say, this is going to be an expensive compound to make as it is not available commercially but must be synthesized from costly silver nitrate. The other methods mentioned in Vogels 5th masterpiece... 

V. a term used to describe a voltage difference between one electrode and another VCDT. Vienna canyon diabolo troilite (actually silver sulfide used as a replacement standard for CDT [sulfur isotopes])... 

Tungsten—silver contacts are made similarly, but can be operated in air because of the greater stabiUty of silver. The three standard compositions of this class include tungsten—silver, tungsten carbide—silver, and molybdenum—silver. 

Eigure 11 illustrates the superior conductivity of P/M silver—nickel or silver—cadmium oxide contacts when compared with contacts made by standard melting techniques and formed from soHd-solution alloys. 

Silver compounds, available from commercial suppHers, are expensive. Reagent grades of sHver(I) carbonate, cyanide, diethjldithiocarbamate, iodate, nitrate, oxide, phosphate, and sulfate are available. Standardized solutions of silver nitrate are also available for analytical uses. Purified grades of sHver(I) acetate, bromide, cyanide, and iodide can be purchased silver nitrate is also made as a USP XX grade for medicinal uses (6). 

Quantitative. Classically, silver concentration ia solution has been determined by titration with a standard solution of thiocyanate. Ferric ion is the iadicator. The deep red ferric thiocyanate color appears only when the silver is completely titrated. GravimetricaHy, silver is determined by precipitation with chloride, sulfide, or 1,2,3-benzotriazole. Silver can be precipitated as the metal by electro deposition or chemical reduciag agents. A colored silver diethjldithiocarbamate complex, extractable by organic solvents, is used for the spectrophotometric determination of silver complexes. 

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