Silver sterling

Stellite 6 Stellite 6B Stellite 12 Sterling silver Super Anoxin Superantinit Thermisiiid E Tombac... 

C04-0148. Silver jewelry is usually made from silver and copper alloys. The amount of copper in an alloy can vary considerably. The fmest-quality alloy is sterling silver, which Is 92.5% by mass silver. To determine the composition of a silver-copper alloy, a jeweler dissolved 0.135 g of metal shavings in 50 mL of concentrated nitric acid and then added 1.00 M KCl solution until no more precipitate formed. Filtration and drying yielded 0.156 g of AgCl precipitate. What was the mass composition of the silver alloy ... 

One way that a solid metal can accommodate another is by substitution. For example, sterling silver is a solid solution containing 92.5% silver and 7.5% copper. Copper and silver occupy the same column of the periodic table, so they share many properties, but copper atoms (radius of 128 pm) are smaller than silver atoms (radius of 144 pm). Consequently, copper atoms can readily replace silver atoms in the solid crystalline state, as shown schematically in Figure 12-4. 

Metals have characteristics that make them desirable for construction, implements, and ornamental uses such as in jewelry. Metals have been so important that the names Chalcolithic, Bronze, and Iron Age have been applied to epochs of history. Metals have an enduring quality. They are solid, durable, and attractive. The first draft of this passage is being written with a pen made of sterling silver (an alloy consisting of 92.5% silver and 7.5% copper). The lure of metals has drawn adventurers to remote places, and they have been the spoils of war. Their intrinsic value is exemplified by the ornaments we wear and the role of metals in monetary systems. 

Figure 23. Cost of sterling silver and of pure gold vs. time, expressed in English pennies per troy ounce, a.d. 1000-1950.

Silver is somewhat rare and is considered a commercially precious metal with many uses. Pure silver is too soft and usually too expensive for many commercial uses, and thus it is alloyed with other metals, usually copper, making it not only stronger but also less expensive. The purity of silver is expressed in the term fitness, which describes the amount of silver in the item. Fitness is just a multiple of 10 times the silver content in an item. For instance, sterling silver should be 93% (or at least 92.5%) pure silver and 7% copper or some other metal. The fitness rating for pure silver is 1000. Therefore, the rating for sterling silver is 930, and most sliver jewelry is rated at about 800. This is another way of saying that most silver jewelry is about 20% copper or other less valuable metal. 

Where materials may come into contact with acetylcysteine solution, use parts made of the following materials Glass, plastic, aluminum, anodized aluminum, chromed metal, tantalum, sterling silver, or stainless steel. Silver may become tarnished after exposure, but this is not harmful to the drug action or to the patient. 

Silver and its alloys and compounds have numerous applications. As a precious metal, silver is used in jewelry. Also, one of its alloys, sterling silver, containing 92.5 weight % silver and 7.5 weight % copper, is a jewelry item and is used in tableware and decorative pieces. The metal and its copper alloys are used in coins. Silver-copper brazing alloys and solders have many applications. They are used in automotive radiators, heat exchangers, electrical contacts, steam tubes, coins, and musical instruments. 

Fig. 6.3 CycUc voltammogram (1st cycle) of sterling silver (92.5% Ag, 7.5% Cu) in 0.5M NaCH3COO, pH 4, v = lOmV/s copper and silver oxidation peaks, indicating surface passivation in presence of Ata (3-amino,1,2,4-triazole) (from [304])...

Fig. 6.5 Typical negative-going LSV recorded on the upper black squares) and bottom (open circles) face of a sterling silver coupon exposed in cultural institutions. The larger peak intensity measuring at — 1.6 on upper face indicates a selective attack of this face that is probably due to the deposition of particulate matter...

Pure silver has one drawback —it is almost as soft as copper. That s why most silver is alloyed with copper to make it- harder. Sterling silver — a famous alloy used for jewelry — contains 7.5 parts copper to 92.5 parts silver. Only %> of American silver coins is silver — the rest is copper. 

Silver in the twentieth century can be classified an industrial commodity. For most of the 19th century, silver was a monetary metal. Industrial consumption of silver is principally in photographic film, electrical contacts, batteries and brazing alloys. Sterling silver and silver plated copper alloys are used extensively for tableware and for jewelry and other decorative art. Recently, the field, of commemorative and collector arts has become a substantial market for silver alloys, particularly sterling silver. 

STERLING SILVER. Silver alloy, usually with copper, containing at least 92.5% silver. 

These sterling silver candlesticks are a solid/solid solution of 92.5% silver and 7.5% copper. 

When some alloys are formed, atoms of one metal replace atoms of another metal. These alloys are classified as substitution alloys. When a substitution alloy is formed, the atoms of metals forming the alloy are about the same size. Therefore, one kind of atom can fit into a space vacated by another atom. In sterling silver, about 7% of the atoms are copper. These copper atoms are randomly dispersed throughout the metallic crystalline silver atoms. Pewter and brass are other examples of substitution alloys. 

When we determined the crystalline structure of solids in Chapter 4, we noted that most transitional metals form crystals with atoms in a close-packed hexagonal structure, face-centered cubic structure, or body-centered cubic arrangement. In the body-centered cubic structure, the spheres take up almost as much space as in the close-packed hexagonal structure. Many of the metals used to make alloys used for jewelry, such as nickel, copper, zinc, silver, gold, platinum, and lead, have face-centered cubic crystalline structures. Perhaps their similar crystalline structures promote an ease in forming alloys. In sterling silver, an atom of copper can fit nicely beside an atom of silver in the crystalline structure. 

When metals are combined to make alloys, the resulting alloy has a combination of the original metal properties. Copper is most often combined with silver to make jewelry. Pure silver is too soft to be used for jewelry. Copper metal in solution with the silver produces a hard product suitable for jewelry fabrication. Sterling silver consists of 925 parts silver and 75 parts copper. Jewelry with less than 90 parts silver cannot be labeled silver. 

Sterling silver, silver, and copper, or gold, can be used to cast a jewelry piece with a minimal amount of health hazard. Alloys with large amounts of cadmium, chromium, nickel, antimony, and arsenic should not be used. 

Uses. Much silver is used in the form of alloys. Alloys of copper and silver are much harder than pure silver and equally or more resistant to corrosion. Sterling silver and silver coins are alloys of this type. Small amounts of silver are used in the electroplating of a wide variety of objects, in the silvering of mirrors, and so forth. This metal is of real value in the form of compounds such as silver nitrate (AgN03), commonly known as lunar caustic, which is used in medicine (to cauterize wounds) and in the manufacture of indelible inks. Silver bromide (AgBr) is an extremely important compound because of its use in photography. 

Most modem silver mined has been used to make photographic film emulsions, in plating, and in alloys for tableware, jewelry, and electrical equipment. Sterling silver is an expression of purity, being at least 92.5% silver. This is expressed either with the word sterling, 0.925 (the is often omitted), or the Lion Passant hallmark. Fine silver is 99.9% pure, but is too soft for most applications. This is the standard purity for silver bullion, as a commodity. 

Sterling silver 92.5% silver, alloyed with other metals, usually copper Coin silver 90% silver, 10% copper... 

Silver is an excellent conductor of heat and electricity and a good reflector of light. It is relatively immune to oxidation but becomes tarnished by exposure to sulfur compounds in exceedingly small concentrations. It is an excellent electroplating metal and can also be deposited in thin films by evaporation. In Dewar flasks and other vacuum glassware, it is deposited from an aqueous medium by the Brashear process. Silver is an excellent brazing material and an important constituent of silver solder. The term silver is often applied to alloys of silver with copper for example Sterling silver contains 7.5 percent copper. Fine silver is 99.9+ percent silver. 

Use and exposure Silver is a very ductile and malleable precious metal. A major use of silver is as jewelry and silverware made from sterling silver and standard silver for traditional purposes. Silver also is used in photography and to make solder and brazing alloys, electrical contacts, and high-capacity silver-zinc and silver-cadmium batteries. Silver has the highest electrical conductivity of all metals—even higher than copper. ... 

In a substitutional alloy some of the host metal atoms are replaced by other metal atoms of similar size. For example, in brass about one-third of the atoms in the host copper metal are replaced by zinc atoms, as shown in Fig. 16.25(a). Sterling silver (93% silver and 7% copper), pewter (85% tin, 7% copper, 6% bismuth, and 2% antimony), and plumber s solder (67% lead and 33% tin) are other examples of substitutional alloys. 

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