Reaction Equilibrium/equilibria specific kinds

As shown in Fig. 24, the mechanism of the instability is elucidated as follows At the portion where dissolution is accidentally accelerated and is accompanied by an increase in the concentration of dissolved metal ions, pit formation proceeds. If the specific adsorption is strong, the electric potential at the OHP of the recessed part decreases. Because of the local equilibrium of reaction, the fluctuation of the electrochemical potential must be kept at zero. As a result, the concentration component of the fluctuation must increase to compensate for the decrease in the potential component. This means that local dissolution is promoted more at the recessed portion. Thus these processes form a kind of positive feedback cycle. After several cycles, pits develop on the surface macroscopically through initial fluctuations. 

More commonly, we know the equilibrium constant and only initial concentrations of reactants and need to find the equilibrium concentrations of the reactants or products. These kinds of problems are generally more involved than those we just examined and require a specific procedure to solve them. The procedure has some similarities to the one used in Example 14.5 and 14.6 in that we set up an ICE table showing the initial conditions, the changes, and the equilibrium conditions. However, unlike Example 14.5 and 14.6, here the changes in concentration are not known and are represented with the variable x. For example, consider again the simple reaction ... 

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