Where the Equilibrium Concentration of Ligand is Known

Cases Where the Equilibrium Concentration of the Ligand is Known 

Once the equilibrium ligand concentration is known, then the aj values and, therefore, the for all the species can be obtained. This represents an exact analogy to the procedure in finding the concentrations of all the species in a Bronsted acid-base system when the pH is known. 

Let us consider a solution in which C u is 0.005 M and with various, but known, equilibrium concentrations of ammonia. What are the concentrations of each Cu-containing species at any or all of the equilibrium concentrations of NH3 The stepwise formation constants for copper amine complexes are Log K j = 4.31, Log = 3.67 Log Kq = 3.04 and Log Kj-4 = 2.30. 

As with the acid base system, when the spreadsheet layout appears on the screen, use the first row to suitably label all the columns with the quantities needed in the problem starting with the critical variable, log [NH3] in column A. Now, in the adjacent columns, enter labels for these related and 

Remember that all aj L values have the same denominator and, since is simply 1/denominator, it can be transformed to the other a values by multiplying by the appropriate numerator Bj[NH3], B[NH3], etc. Once you have written the correct formulas in D2 to G2 (for [Cu(NH3)4 ]) in the next five columns (H2 to L2), write formulas for the logarithms of each of the species, e.g., in H2, place LOG(C2), and for forth. Now, copy the values from B2 to L2 by the command /EC(/8C /C over the entire range you selected in column A. 

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