28.5.2—Write an expression for a Kstab of a complex

For a formation equation, Kstab is the concentration of the complex divided by the concentrations of the free metal ion and ligands, each raised to its stoichiometric coefficient.

Write the balanced equilibrium first, then omit pure solids, pure liquids and the solvent. Water is therefore not included when it is the solvent.

For M²⁺ + 4NH₃ ⇌ [M(NH₃)₄]²⁺, Kstab = [[M(NH₃)₄]²⁺]/([M²⁺][NH₃]⁴).

Do not put ligand count in front of a concentration, forget the power of four, or include [H₂O] merely because water appears in the hydrated starting ion.