Difference between evolution during solution

The relative amounts of molybdenum and phosphorus adsorbed onto y-alumina from molybdate and/or phosphate solutions by sequences of pulses are shown in Fig. 21 (59). When the solutions contain only molybdenum or phosphorus oxo-species, the amounts of molybdenum or phosphorus retained are high for the first pulses (—80 and —100%, respectively) and decrease in further pulses. On the other hand, the evolution during pulses with a Mo + P solution, which is equivalent to coimpregnation of molybdenum and phosphorus, is quite different. The molybdenum adsorption decreases significantly as a result of addition of phosphorus due to the strong competition between phosphorus- and molybdenum-containing anions. In addition, the molybdenum adsorption decrease in the presence of phosphorus can also be explained by the formation (Eqs. 15 and 16) of phosphomo-lybdate species that have lower affinities for alumina ... 

The evolution of a new set of electrochemical waves (as opposed to the gradual shifting of the redox couple) on addition of guest species may be due to a number of factors. If the complex formed has a particularly high stability constant and has a redox potential which is markedly different from that of the free ligand, a new set of waves may be observed. However, if the decomplexation kinetics of the complex formed is particularly slow on the electrochemical time scale then, as the potential is scanned between the vertex points during a cyclic voltammetric experiment, the solution complexed species will be stable over this time period and the two sets of waves will correspond to free ligand and complex. Therefore care should be taken to determine the cause of the evolution of a new set of electrochemical waves and... 

The number of independent reactions and substances is an essential important characteristic, not only of an equilibrium, but also of non-equilibrium chemical systems. In the latter, however, conditions of chemical equilibrium (see equation 1.31) are infringed. Firstly, this means that the numbers of independent reactions and substances of nonequilibrium system cannot be determined on the basis of the same criteria as for equilibrium systems successively, not only numbers but also their physical sense should be different. Secondly, during the evolution of chemical system from the initial state to a final equilibrium one, relations between their parameters are renewed continuously, but it is necessary to analyze them in such a way that characteristic numbers (that is numbers of independent reactions and substances of a non-equilibrium sy.stem) can be analyzed by a state function of a non-equilibrium system evolution. This question has not only a concrete scientific value, but also a methodological one and its solution is based on the principle of abridged description of non-equilibrium systems [ 11-13]. 

---