Silver metal electrode

The student then added 10. mL of 1.0 M NaCl solution to an empty beaker. He then added one drop of 1.0 M AgN03 to the beaker and stirred well. Since there is an abundance of Cl in the beaker, and the amount of NaCl (10. mL) is magnitudes greater than the one drop of 1.0 M AgN03, it can be assumed that most of the Ag+(aq) will combine with the CT(aq) and that the concentration of the Cl (aq) will remain essentially 1.0 M. A silver metal electrode was immersed in this solution and connected through the salt bridge to the Zn I Zn2+ half-cell. The potential difference was measured as 0.91 volts. 

The first step in the deposition process is that in which an ion crosses the electrified interface, i.e., the charge-transfer reaction. Picture the situation (Fig. 7.122). A hydrated ion (e.g., a silver ion) is waiting at the OHP. In the direction of the silver metal electrode, there is the three-dimensional network, or lattice, consisting of silver ions cemented together by an electron gas. The silver ions in the lattice each lay claim to an electron of the electron gas in this sense, they can be said to be neutral and... 

A metal (Me) acts as an electrode in the electrolyte containing its ions. The metal is said to be electroactive according to Me <-> Me"+ + n c. An example is the Ag/ Ag+ electrode represented in Figure 3.1.3 (i.e. a silver metal electrode immersed in an electrolyte containing silver ions). The Zn/Zn++ electrode is another metal/ metal ion electrode. It is widely used in batteries. 

An electrode of this type is a metal in contact with a solution containing its cation. An example is a silver metal electrode dipping in a solution of silver nitrate. 

An electrochemical cell consists of a silver metal electrode immersed in a solution with [Ag+] = 1.0 Mseparated by a porous disk from a copper metal electrode. If the copper electrode is placed in a solution of 5.0 M NH3 that is also 0.010 M in Cu(NH3)4, what is the cell potential at 25°C ... 

With a silver metal electrode, (Ag(s) is virtually constant and is taken as unity. 

After the first detection of the enhanced Raman signals from pyridine adsorbed on a silver metal electrode it is now well established that this phenomenon is caused by an enhancement of the Raman cross section of adsorbates at an electrode-electrolyte interfaceon metal colloids and at a metal-vacuum surface... 

TAKAHASHI and YAMAMOTO, and later, KARPACHEV, OVSHINNIKOV and YUSHINAp studied oxi-dation and reduction of silver metal electrodes at the interface Ag/Ag S I. Obtained current-voltage curves are reported on fig.14, curve 1. Curve 2 represents the current-voltage curve for a charge-transfer controlled reaction. The overall electrochemical raction is... 

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]. 

Potentiometric Titrations. If one wishes to analyze electroactive analytes that are not ions or for which ion-selective electrodes are not available, two problems arise. First, the working electrodes, such as silver, platinum, mercury, etc, are not selective. Second, metallic electrodes may exhibit mixed potentials, which may arise from a variety of causes. For example, silver may exchange electrons with redox couples in solution, sense Ag" via electron exchange with the external circuit, or tarnish to produce pH-sensitive oxide sites or Ag2S sites that are sensitive to sulfide and haUde. On the other... 

Measuring electrodes for impressed current protection are robust reference electrodes (see Section 3.2 and Table 3-1) which are permanently exposed to seawater and remain unpolarized when a small control current is taken. The otherwise usual silver-silver chloride and calomel reference electrodes are used only for checking (see Section 16.7). All reference electrodes with electrolytes and diaphragms are unsuitable as long-term electrodes for potential-controlled rectifiers. Only metal-medium electrodes which have a sufficiently constant potential can be considered as measuring electrodes. The silver-silver chloride electrode has a potential that depends on the chloride content of the water [see Eq. (2-29)]. This potential deviation can usually be tolerated [3]. The most reliable electrodes are those of pure zinc [3]. They have a constant rest potential, are slightly polarizable and in case of film formation can be regenerated by an anodic current pulse. They last at least 5 years. 

The cell shown in Figure 19-16 can serve as an example for calculations using Equation. One cell contains aqueous 1.00 M iron(in) chloride in contact with an iron metal electrode, and the other cell contains 1.00 M KCl in contact with a silver-silver chloride (AgCl/Ag) electrode. The half-reactions for these electrodes follow ... 

C19-0099. In a silver coulometer (see Problem ), both electrodes are silver metal. Draw a molecular picture that illustrates the reactions that occur during operation of this coulometer. 

A picture similar to that just described is seen for metal electrodes when the solution contains a complexing agent (e.g., for the silver electrode when KCN has been added to a AgNOj solution). Then the complex formation equilibrium... 

Despite the fact that the electrodeposition of copper and silver at the water-DCE and the water-dichloromethane interfaces has been generally regarded as the first experimental evidence for heterogeneous ET at externally biased ITIES [171], a very limited amount of work has dealt with this type of process. This reaction has also theoretical interest because the molecular liquid-liquid interface can be seen as an ideal substrate for electrochemical nucleation studies due to the weak interactions between the interface and the newly formed phase and the lack of preferential nucleation sites always present at metallic electrodes. 

Metals such as silver, copper, mercury, lead and cadmium respond to variations in the activities of their own ions in a Nernstian and reproducible manner, e.g. for silver, the electrode reaction is Ag+ + e =... 

Reactions involving charge transfer through the interface, and hence the flow of a current, are called electrochemical reactions. Two types of such reactions are indicated in Fig. 1.1. The upper one is an instance of metal deposition. It involves the transfer of a metal ion from the solution onto the metal surface, where it is discharged by taking up electrons. Metal deposition takes place at specific sites in the case shown it is a hollow site between the atoms of the metal electrode. The deposited metal ion may belong to the same species as those on the metal electrode, as in the deposition of a Ag+ ion on a silver electrode, or it can be different as in the deposition of a Ag+ ion on platinum. In any case the reaction is formally written as ... 

The oxidation of hydroxide ion in acetonitrile at copper, silver, gold, and glassy-carbon electrodes has been characterized by cyclic voltammetry. In the absence of bases the metal electrodes are oxidized to their respective cations (Cu+, Ag+, and Au+) at potentials that range from -0.2V vs. SCE for Cu to +1.3 V for Au. At glassy carbon OH is oxidized to 0 - (+0.35 V vs SCE) and then to... 

Worked Example 7.19 We immerse a piece of silver metal into a solution of silver ions at unit activity and at s.t.p. The potential across the cell is 0.799 V when the SHE is the negative pole. What is the standard electrode potential E of the Ag+, Ag couple ... 

No effect of the nature of metallic electrodes was found on the tumor destruction,7 38 39 e.g., silver and tungsten electrodes gave results similar to platinum 7 this also means that a slight anodic dissolution of platinum that might occur during the ECT experiment is not responsible for the necrosis of the tumor.7... 

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