Silver-copper cell

Given the half-cell potentials in Table 17.2, calculate the cell potential of (a) the Daniell cell, (b) the copper/silver cell. 

The Zinc-Copper Cell 21-10 The Copper-Silver Cell... 

Recall that in the zinc-copper cell the copper electrode is the cathode now in the copper-silver cell the copper electrode is the anode. 

Left) A spiral of copper wire was placed in a colorless solution of silver nitrate, AgN03. The silver has been displaced from solution and adheres to the wire. The resulting copper nitrate solution is blue. The same reaction occurs when the two half-reactions are separated in the copper-silver cell (see Figure 21-7). (Right) No reaction occurs when silver wire is placed in a blue copper sulfate solution. The reaction... 

The Zinc-Copper Cell 21-10 The Copper-Silver Cell Standard Electrode Potentials 21-11 The Standard Hydrogen Electrode 21-12 The Zinc-SHE Cell 21-13 The Copper-SHE Cell 21-14 Standard Electrode Potentials 21-15 Uses of Standard Electrode Potentials 21-16 Standard Electrode Potentials for Other Half-Reactions 21-17 Corrosion 21-18 Corrosion Protection... 

The same spontaneous (product-favored) reaction occurs when the two half-reactions are separated in the copper-silver cell (see Figure 21-7). 

Lead in water may he analyzed very precisely at low concentrations hy anodic stripping voltametry using an electrochemical analyzer static or controlled growth mercury drop electrodes, reference calomel or silver-silver chloride electrodes and silica or TEE cells. Copper, silver, gold, and certain organic compounds may interfere in the test. (APHA, AWWA and WEE. 1998. Standard Methods for the Examination of Water and Wastewater, 20 ed. Washington, D.C. American Public Health Association.)... 

Silver is employed for low resistance electrical contacts and conductors, and in silver cell batteries. Antimony is used in lead add storage batteries to improve the workability of the lead and lead oxides. Copper and copper alloy wires, connectors, cables, switches, printed drcuit boards, and transistor and rectifier bases are common throughout the industry. Nickel is used in high resistance heating elements, glass-to-metal seals, batteries, and spedalty steels for power generation equipment Household appliances employ stainless and electroplated steel containing nickel. 

G. J. Burch and Y- H. Yeley found that when the metals, copper, silver, bismuth, and mercury are introduced into purified nitric acid of varying degrees of concentration, and a couple made with platinum, the electromotive force of such a cell increases considerably until it reaches a constant and (in most cases) a maximum value. This rise of electromotive force is attributed to the production of nitrous... 

Electrolysis is used in a wide variety of ways. Three examples follow (1) Electrolysis cells are used to produce very active elements in their elemental form. The aluminum industry is based on the electrolytic reduction of aluminum oxide, for example. (2) Electrolysis may be used to electroplate objects. A thin layer of metal, such as silver, can be deposited on other metals, such as steel, by electrodeposition (Eig. 14-2). (3) Electrolysis is also used to purify metals, such as copper. Copper is thus made suitable to conduct electricity. The anode is made out of the impure material the cathode is made from a thin piece of pure copper. Under carefully controlled conditions, copper goes into solution at the anode, but less active metals, notably silver and gold, fall to the bottom of the container. The copper ion deposits on the cathode, but more active metals stay in solution. Thus very pure copper is produced. The pure copper turns out to be less expensive than the impure copper, which is not too surprising when you think about it. (Which would you expect to be more expensive, pure copper or a copper-silver-gold mixture )... 

Figure 3.22. Unit cell representations of two varieties of AuCu superlattices. For the AuCu II superlattice, M refers to the length of repeat unit, and APB indicates the antiphase boundaries between adjacent periodic arrays. Republished with the permission of the International and American Associations for Dental Research, from Determination of the AuCu Superlattice Formation Region in Gold-Copper-Silver Ternary System , Uzuka, T. Kanzawa, Y. Yasuda, K. J. Dent. Res. 1981, 60, 883 permission conveyed through Copyright Clearance Center, Inc.

Metals that have been produced by pyrometallurgical methods, such as copper, silver, nickel, and tin, are too impure for many purposes, and electrorefining is used to purify them further. Crude metallic copper is cast into slabs, which are used as anodes in electrolysis cells that contain a solution of CUSO4 in aqueous H2SO4. Thin sheets of pure copper serve as cathodes, and the copper that dissolves at the anodes is deposited in purer form on the cathodes (Fig. 17.18). Impurities that are more easily oxidized than copper, such as nickel, dissolve along with the copper but remain in solution elements that are less easily oxidized, such as silver and gold, do not dissolve but fall away from the anode as a metallic slime. Periodically, the anode slime and the solution are removed and further processed for recovery of the elements they contain. 

Figure 21-7 The copper-silver voltaic cell utilizes the reaction...

Other work has demonstrated that it is possible to switch ON and OFF luminescence by reduction/oxidation, and it has been demonstrated that such switching is possible inside an OTTLE cell. Many alkynyl complexes, especially those of rhenium, platinum,copper, silver or gold " are highly luminescent from their excited MLCT or metal perturbed 71 states. This opens up the possibility to significantly influence their emissive properties by redox processes. An interesting example is found in recent work of Wong et Unlike other rhenium(I)-alkynyl complexes, heterobimetallic... 

Technology has made modern batteries smaller, safer, and more dependable than our crudely constructed copper-zinc voltaic cell. In fact, the silver cell (Figure 9.11) is sufficiently safe and nontoxic that it can be implanted in the human body as a part of a pacemaker circuit that is used to improve heart rhythm. A rather futuristic potential application of voltaic cells is noted in A Medical Perspective Turning the Human Body into a Battery on page 261. 

We can always change the terminal of the voltmeter to which we connect an electrode, so for the time being let s simply adjust the measurement to show a positive voltage every time. If we apply this technique to the example of copper and silver, what do we observe The cell Cu(s) Cu (l M) Ag (l M) Ag(s) has a potential of 0.462 V. If we take the same copper half-cell and connect it instead to a half-cell that reduces iron(III) to iron(II), we find that the measured cell potential is 0.434 V. If this iron electrode is connected to the silver one, the resulting cell potential is 0.028 V. These numbers are clearly related 0.462 = 0.434 + 0.028 (Figure 13.8). This observation is important for two reasons. First, it shows a behavior of cell potentials that is akin to that of a state function. Second, it suggests that if we choose a specific standard electrode to which we compare all other electrodes, we can devise a practical system for determining cell potential. 

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