posted by Will
The problem is as follows:
The toxic metal cadmium Cd2+ has a tendency to complex with as many as 4 Cl- ions. The complexation reactions can be written as:
Cd2+ + Cl- ---> CdCl+ log Kf,1 = 1.98
Cd2+ + 2Cl- ---> CdCl2^0 log Kf,2 =2.60
Cd2+ + 3Cl- ---> CdCl3- log Kf,3 = 2.40
Cd2+ + 4Cl- ----> CdCl42- log Kf,4 = 2.50
Task: Compute the percentage of total Cd2+ in a solution that remains uncomplexed (free Cd2+ ) if the Cl- concentration is 0.005 M (ignore activity coefficient correction, assume activities equal concentrations).
So I know that I will likely have to use the complex formation equilibrium constants in tandem with the initial Cl- concentration of 0.005 M, but I'm not exactly sure how to execute the problem. How can I obtain insight into the total uncomplexed Cd2+ with just this information? I was thinking about setting up each species with regard to the given K constants and plugging and iterating for values of Cd2+, but this doesn't seem like the route to go. Anybody know of any details I may need to make use of / where to start with this problem? Any help, in any form, would be appreciated.