Homogeneous Chemical Reactions her

This last general equation is implemented in the function COFUNC, described in Appendix E. The formula is applied in the seven-point form in the example program CHRONOEX described in Appendix E, simulating chronopotentiometry. It must be applied before every new iteration, in order for the Co value to be in accord with the other C values. In this program, the current is constant and it is the value of Co which is displayed and this should go to zero at T = 1 (Sect. 2.4.2). A more appropriate display might be the electrode potential, which is always the measured quantity, but this will be dealt with together with the more detailed discussion of boundary conditions in Chap. 6. 

One of the simplest examples of a homogeneous chemical reaction (her) is the Reinert-Berg system [11], in which an electroactive species is generated, for example by means of a light flash, and then reduced as a Cottrell system, while the species decays chemically with a first-order reaction. The reactions are then 

If several species are involved (in this case there is the product prod, but we are not interested in it), the equations are extended in an obvious manner, apart from some tricks to be seen in a later chapter in connection with implicit methods. This is one of the attractive aspects of method EX. If the her is second-order, there will be a term in C in the discrete equation, and it will present no problem in the discretisation step [12]. 

If one is computing the two changes separately (the parallel method), and given that the chemical reaction itself is usually tractable analytically, this component need not be simulated. For a first-order reaction as seen in (5.11) and (5.12), the last part 

There are, however, several problems here. The first is that in writing the governing equation in discrete form as above, we are in effect uncoupling diffusional changes from chemical changes. Numerically, they appear to take 

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As described in Chap. 5, for the simulation of a first order homogeneous chemical reaction her) coupled to diffusion such as the Reinert-Berg mechanism (5.11) we have the governing equation... 

A systematic classification of homogeneous chemical reactions (her) in electrochemical cells can be read in Chapter 1 in Volume 8 and here, only some examples that impinge on simulations will be mentioned. 

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