Nernst equation for

Although this treatment of buffers was based on acid-base chemistry, the idea of a buffer is general and can be extended to equilibria involving complexation or redox reactions. For example, the Nernst equation for a solution containing Fe + and Fe + is similar in form to the Henderson-Hasselbalch equation. 

Before the equivalence point the titration mixture consists of appreciable quantities of both the oxidized and reduced forms of the analyte, but very little unreacted titrant. The potential, therefore, is best calculated using the Nernst equation for the analyte s half-reaction... 

Although EXo /ATcd is standard-state potential for the analyte s half-reaction, a matrix-dependent formal potential is used in its place. After the equivalence point, the potential is easiest to calculate using the Nernst equation for the titrant s half-reaction, since significant quantities of its oxidized and reduced forms are present. 

At the equivalence point, the moles of Fe + initially present and the moles of Ce + added are equal. Because the equilibrium constant for reaction 9.16 is large, the concentrations of Fe and Ce + are exceedingly small and difficult to calculate without resorting to a complex equilibrium problem. Consequently, we cannot calculate the potential at the equivalence point, E q, using just the Nernst equation for the analyte s half-reaction or the titrant s half-reaction. We can, however, calculate... 

Note, again, that the Nernst equations for both E and Ta are written for reduction reactions. The cell potential, therefore, is... 

Making appropriate substitutions into the Nernst equation for the electrochemical cell (see Example 11.2)... 

To begin, we write Nernst equations for the two measured cell potentials. The cell potential for the sample is... 

The shift in the voltammogram for a metal ion in the presence of a ligand may be used to determine both the metal-ligand complex s stoichiometry and its formation constant. To derive a relationship between the relevant variables we begin with two equations the Nernst equation for the reduction of O... 

Nernst equation for concentration cells, 467 theorem, 484, 489, 508, 531 theory of galvanic cells, 474... 

Since the electrolyte membrane only allows the conduction of ions, the electrons are forced through an exterior circuit, creating an electromotive force. The voltage generated by such a cell is given by the Nernst equation. For the hydrogen-oxygen reaction we can write ... 

The classification of electrodes is based upon the chemical nature of the substances participating in the electrochemical process [75]. Electrodes of the first type are systems in which the reduced forms are metals of electrodes and oxidized forms are ions of the same metal. Electrodes of second type are systems in which the metal is covered by a layer of low soluble salts (or oxide), and the solution contains anions of these salts (for oxide-OH ions). The Nernst equation for electrodes of the second type can be written as ... 

This equation is often called the Nernst equation for the ITIES, and the term A is in fact the standard Gibbs energy of transfer expressed on a potential scale, since,... 

EXAMPLE 14.7. Write the Nernst equation for the Cu/Ag cell of Example 14.6. 

Electrode and therefore cell potentials are very important analytically as their magnitudes are determined by the activities of the reactants and products involved in the electrode reactions. The relation between such activities and the electrode potential is given by the Nernst equation. For a general half-cell reaction written as a reduction, i.e. aA + bB +. .. ne = xX + yY +. . ., the equation is of the form... 

In this scheme, H, G and HG in normal or subscript positions represent the host, guest and complex species respectively subscripts ox and red indicate that the corresponding symbols or parameters refer to molecules in oxidized and reduced states E° is the formal potential of the electron transfer reaction and K is the stability constant. According to thermodynamics, there are four relationships linking the concentrations of the four molecules at the four corners of the square. These are two Nernst equations for the upper (2) and lower (3) electron transfer reactions,... 

The Nernst equations for this reaction, as well as for CO and CH4 reacting with O2, that can occur in various fuel cells, are listed in Table 2-2. 

A generalized Nernst equation for this redox couple is also provided by the theory... 

Nernst Equation for the Concentration Dependence of Metal/Metal-Ion Potential. 

Nernst Equation for Concentration Dependence of RedOx Potential. Equation (5.9) applied to the general RedOx electrode (5.16) yields... 

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