Stoichiometry of reaction and nomenclature

1 Stoichiometry of reaction and nomenclature. Stoichiometry refers to the number of moles of a chemical component reacting to form a species. Consider the reaction 

The triplets p, q, r are known as the stoichiometric coefficients of the chemical components in the formation equation of the complex, and are often quoted as subscripts next to the symbol used for the formation constant, which in this case is (3, so that the equilibrium formation constant would be defined as 

An example would be reaction between Al3+ and a diprotic carboxylic acid such as oxalic acid (H2L) where L refers to the oxalate ligand. 

The formation constants and associated stoichiometries have been reported for a number of different aluminium oxalic acid complexes (Sjoberg and Ohman, 1985), and these are shown in Table 5.1. From the stoichiometric coefficients the reaction for the formation of A1L2 can be deduced and expressed more fully as 

Notice, however, that although the stoichiometric coefficient for the proton in the formation equation is —4, it is +4 when written on the right-hand side of equation (5.22). This is because the stoichiometric coefficient refers to the equation for the formation of the species in terms of the defined components thus rearranging we get 

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