Spreadsheet equation for auxiliary complexing agent. Consider the titration of metal M (initial concentration CM, initial volume VM) with EDTA (concentration CEDTA, volume added VEDTA) in the presence of an auxiliary complexing ligand (such as ammonia). Follow the derivation in Section 11-4 to show that the master equation for the titration is where Kf is the conditional formation constant in the presence of auxiliary complexing agent at the fixed pH of the titration (Equation 11-18) and [M]free is the total concentration of metal not bound to EDTA. [M]free is the same as Mtot in Equation 11-15. The result is equivalent to Equation 11-11, with [M] replaced by [M]free and Kf replaced by Kf .

Step 1 of 2

The equation is 11-8 can be written as follows:

The for above equation can be written as follows:

Where,

represents the metal’s concentration that is not bound to EDTA

[EDTA] represents all EDTA’s concentration that is not bound to metal.