Where the Equilibrium Concentration of Ligand Not Known

Cases Where the Equilibrium Concentration of the Ligand is not Known 

We wish to find the composition of a solution that is 0.005 M Cu and 0.010 M in NH3. The calculation proceeds by first calculating the [NH3], then using this value to obtain a values. We can start as if the solution consisted of 0.005 M Cu(NH3)2. The LBE for this is 

Starting with Cu(NH3)2, production of the species on the left required addition of NH3, those on the right resulted when NH3 was released. Naturally, [NH3] itself is on the left it requires NH3. 

Every term in Equation 5-5 can be expressed in terms of [NH3], the only variable in the a expressions. The solution to this problem can be found simply by using the pointer function, P, which here is 

What is the pointer function for 0.005 M Cu(NH3)3 The LBE and associated pointer function applicable in 0.005 M Cu containing a threefold excess of NH3, which is equivalent to Cu(NH3)3, can be seen as 

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