Yesterdays post focused on chelating agents. These are spieceies that can form more than one dative co-ordinate bond with transition metal ions.
I ended writing that chelation forms very stable complex ions but why does chelation form stable complexes?
Well, the answer is quite deep routed in entropy. Essentially, the reactions produce a very large change in entropy. The enthalpy change is negligible which means that the Gibbs free energy becomes very negative (and very feasible or very spontaneous).
This is quite hard to explain in words but far easier in equations. The folloiwn gequation sums it up quite nicely. EDTA4- is a chelating agent that can from six dative co-ordinate bonds:
As the enthalpy change is negligible, the equation is always negative and voila, we have an good example of a spontaneous reaction!
Tomorrow, some more top tips for success.