Ladderdiagrammen: Complexatie-evenwichten

For metal-ligand complexation equilibria, the scale of the ladder diagram is denoted by the concentration of unreacted or free ligand, where the horizontal line is the log of its formation constant.

Consider the ladder diagram for the metal-ligand complexes of cadmium and ammonia.

The four horizontal lines correspond to the log of stepwise formation constants and demarcate the predominant regions for different complex forms.

For example, the Cd²⁺ species dominates at log K₁ or pNH₃ values higher than 2.55.

Ladder diagrams of complexation reactions can be drawn using both cumulative and stepwise formation constants.

At lower pNH₃ values, the concentration of the [Zn(NH₃)₄]²⁺ ion is higher; with increasing pNH₃ values, the presence of the [Zn(NH₃)₃]²⁺ ion increases. However, at higher pNH₃ values, Zn²⁺ predominates.