Concentration cell worked

Is the following statement true or false Concentration cells work because standard reduction potentials are dependent on concentration. Explain. 

How a Concentration Cell Works Suppose that both compartments of a voltaic cell house the Cu/Cu" half-reaction. The cell reaction is the sum of identical half-reactions, written in opposite directions, so the standard half-cell potentials... 

How a Concentration Cell Works Let s see what is happening as this cell operates ... 

Similar considerations apply of course to the opposing electromotive forces of polarisation during electrolysis, when the process is executed reversibly, since an electrolytic cell is, as we early remarked, to be considered as a voltaic cell working in the reverse direction. In this way Helmholtz (ibid.) was able to explain the fluctuations of potential in the electrolysis of water as due to the variations of concentration due to diffusion of the dissolved gases. It must not be forgotten, however, that peculiar phenomena—so-called supertension effects—depending on the nature of the electrodes, make their appearance here, and com-... 

As has been pointed out, another interesting type of electrode-concentration cell is that comprising two hydrogen electrodes working at different pressures and remaining immersed in a solution of hydrochloric acid. The cell may be represented as ... 

The first two terms on the right-hand side of this equation express the proper overpotential of the electrode reaction rjr (also called the activation overpotential) while the last term, r)c, is the EMF of the concentration cell without transport, if the components of the redox system in one cell compartment have concentrations (cOx)x=0 and (cRed)x=0 and, in the other compartment, Cqx and cRcd. The overpotential given by this expression includes the excess work carried out as a result of concentration changes at the electrode. This type of overpotential was called the concentration overpotential by Nernst. The expression for a concentration cell without transport can be used here under the assumption that a sufficiently high concentration of the indifferent electrolyte suppresses migration. 

The concentration overpotential i/c is the component of the overpotential due to concentration gradients in the electrolyte solution near the electrode, not including the electric double layer. The concentration overpotential is usually identified with the Nernst potential of the working electrode with respect to the reference electrode that is, the thermodynamic electromotive force (emf) of a concentration cell formed between the working electrode (immersed in electrolyte depleted of reacting species) and the reference electrode (of the same kind but immersed in bulk electrolyte solution) ... 

A good example of a concentration cell would be the iron system in the worked example above, in which a(R) = a.cui = U accordingly, for simplicity here, we will assume that the reduced form of the couple is a pure solid. 

Preliminary heats of solution of C0CI2 and CuCl2 have been measured up to 300 C by Cobble and Murray (50). Hydrolysis was suppressed by HC1 addition so that when the work is completed and when the extent of Cl complexing (and Cu + reduction) can be allowed for the data will prove extremely valuable. Preliminary concentration cell studies on the Cl complexing of Cd + and Ni + up to 170 C (51) support the conclusions given earlier that such complexing with first row transition metal ions is likely to be significant by 300°C. 

When electrically connecting both cells, working under the same gas pressure but with electrolytes of different concentration [(o-l)2 > (a+)il ... 

Gas sensors — (a) Gas sensors with liquid electrolytes — Figure 2. can regarded as an Oxygen concentration Cell. They Scheme of a potentiometric gas sensor work depending on electrode material in a broad range... 

Imperial College s Centre for Ion Conducting Membranes is working on perm-selective membranes, and perhaps could develop the concentration cells mentioned in Appendix A (Williams, 2002), pp. 878-891. 

With hydrogen fuel, the large circulator (concentration cell) pressure ratios and unavailable membranes are again obstacles to the realisation in practice of the theoretical work potential. 

Because the potential of an electrochemical cell depends on the concentrations of the participating ions, the observed potential can be used as a sensitive method for measuring ion concentrations in solution. We have already mentioned the ion-selective electrodes that work by this principle. Another application of the relationship between cell potential and concentration is the determination of equilibrium constants for reactions that are not redox reactions. For example, consider a modified version of the silver concentration cell shown in Fig. 11.11. If the 0.10 M AgN03 solution in the left-hand compartment is replaced by 1.0 M NaCl and an excess of solid AgCl is added to the cell, the observed cell potential can be used to determine the concentration of Ag+ in equilibrium with the AgCl(s). In other words, at 25°C we can write the Nernst equation as... 

It will be observed that the process which actually takes place m a concentration cell, either with or without transport, and which gives rise to the e m f, is the tendency of the two solutions to become equal in concentration. If instead of transferring solute from one solution to the other we were to transfer solvent by isothermal distillation from, weak to strong, the same equalisation of concentration could be obviously brought about If we could evaluate the expression for this isothermal distillation work, we could equate it to the electrical work, for if We pass from one equilibnum stage to another by any reversible... 

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