Copper continued

A typical m el ter iastalled in a medium sized brass foundry contains 4500 kg of brass and its inductor is rated 500 kilowatts. Brass is an alloy containing copper and zinc. Zinc vaporizes at temperatures weU below the melting temperature of the alloy. The channel iaductor furnace s low bath temperature and relatively cool melt surface result in low metal loss and reduced environmental concerns. Large dmm furnaces have found use in brass and copper continuous casting installations. 

Figure 1.6 Dark oxide and deposit lobes on a copper continuous caster mold from a steel-making operation. Since heat transfer is high, even small amounts of deposit are unacceptable.

Copper (continued) properties, 400. 408 Core, of earth, 440 Corrosion, 405 Coulomb, 241 Coulombic forces, 416 Coulson, C A., 252 Covalent bonds, 274, 277, 288 elements that form solids using, 302... 

The text has so far confined attention to the electrode potential of only one metal and is henceforward extended to two electrodes. Copper continues to be one metal, and the other introduced into the consideration is zinc. If the copper and the zinc electrodes are placed in a common electrolyte holding ions of both metals, Cu2+ and Zn2+, respectively, both electrodes will have an electrode potential, ECn and Zn respectively. 

Copper (continued) cynates, 17 322, 323 diaminodithioether complexes, 17 185 diazene complexes, 27 232 difluoride, structure, 27 85, 86, 87, 88 dinuclear sites, 40 362-367 diphosphine complexes of, 14 235-239 electron-density distributions of complexes, 27 34, 41... 

Laboratory Methoda Table III. Sample 1 Continued Sample 2 Cu (Copper) Continued Sample 3... 

What happens when the external resistance is made zero, i.e., when the copper and zinc electrodes are brought into electrical contact, or short-circuited (Fig. 12.3). Of course, the copper continues to deposit and the zinc continues to dissolve at a certain current, but the potential difference across the cell will become zero. This thought experiment is equivalent to what happens when a bar of copper and a bar of zinc are welded together and put into an electrolyte containing cupric ions (Fig. 12.4). The zinc dissolves as the copper deposits. Similarly, if, e.g., iron is welded together with some other metal and placed in an electrolytic solution, whether it dissolves will depend on whether its equilibrium potential is more negative or more positive than that of the other metal. 

A closer look at the catalytic cycle, as shown in Fig. 4.12, shows how zinc plays a largely structural role while copper continually changes oxidation state and coordination environment. It should be immediately apparent that one of the by-products is the equally toxic reactive species, hydrogen peroxide. Fortunately a second enzyme, catalase, is present to scavenge the peroxide and convert it to oxygen and water. 

At 10 the arrangement of the solubility curves is that represented by Fig. 82 the solutions rich in copper continue to give triclinic crystals with 5 molecules of water, but the solutions rich in manganese give clinorhombic crystals with 7 molecules of water. 

Hypothesizing Instead of galvaiuzing iron, it can be plated with copper to protect it. What would happen when the copper coating became broken or cracked Would the copper continue to protect the iron as zinc does Explain fully. 

The effect on activity for the dehydrogenation reaction is very different from that for the hydrogenolysis reaction. In the case of ethane hydrogenolysis, adding only 5 at.% copper to nickel decreases catalytic activity by three orders of magnitude. Further addition of copper continues to decrease the activity. However, the activity of nickel for dehydrogenation of cyclohexane is affected very little over a wide range of composition, and actually increases on addition of the first increments of copper to nickel. Only as the catalyst composition approaches pure copper is a marked decline in catalytic activity observed. 

Hypothesize Suppose in galvanization, copper was plated on iron instead of zinc. Would copper continue to protect the iron from corrosion, as zinc does, if the copper coating became broken or cracked Explain. 

The lower chart in Hg. 16.1 is used to determine the trace width for various copper thicknesses. For the same cross-sectional area, the width will be smaller for thick copper and wider for thin copper. Continuing with the example, follow the vertical fine down from 200 sq. mil. into the lower chart to the fine labeled (1 oz/fF ) 0.0014 see the discussion of copper thickness in Section 16.4.5. Following the Une across to the axis labeled CONDUCTOR WIDTH IN INCHES shows that the trace should be 0.15 in. wide for a copper trace that is 0.0014 in. thick. If 3 oz. copper were selected, the trace width wonld be approximately 0.05 in. wide rather than 0.15 in. wide for 1 oz. copper. 

However, closer examination showed that the Cu-Ni system, immediately after the interruption of current, acquires an open circuit potential (or a mixed potential) which hes above the nickel reversible potential and below the copper reversible potential. In addition, the pH of these solutions, i.e. pH = 4, does not allow the formation of nickel oxides on the surface of the nickel. Therefore, in accordance with the mixed potential theory, copper continues to deposit at the expense of nickel dissolution, forming a classic galvanic corrosion cell. This process does not... 

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