Sterling silver, 228 table

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. 

In a substitutional alloy, atoms of the solute occupy sites in the lattice of the solvent metal (Figure 5.8). To maintain the original lattice structure of the host metal, atoms of both components should be of a similar size. The solute atoms must also tolerate the same coordination environment as atoms in the host lattice. An example of a substitutional alloy is sterling silver (used for silver cutlery and jewellery) which contains 92.5% Ag and 7.5% Cu elemental Ag and Cu both adopt ccp lattices and rn,etai(A-g) rjnet3i(Cu) (Table 5.2). 

Sterling silver is a sohd solution of silver and copper. If a piece of a sterhng silver necklace has a mass of 105.0 g and a volume of 10.12 mL, calculate the mass percent of copper in the piece of necklace. Assume that the volume of silver present plus the volume of copper present equals the total volume. Refer to Table 1.5. 

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