Species Selection and Treatment

Attention is now directed to the species MnO(OH). This compound, in which Mn is in an oxidation state of III, in a water system could be written as Mn203, MnO(OH), or Mn(OH)3, the only differences between them being 

In many other cases, free energy values will lead to conclusions regarding which species is the most stable. A further illustration of the importance of species which differ by hydration is A102 and Al(OH)4 , the latter being preferred by free energy calculations (A102 + 2HOH Al(OH)4 ). 

Finally, some considerations with regard to standard free energy values must be taken into account. Many AG° values are well known, some have 

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