Formation constant (Kf)

Definition

The formation constant ($K_f$) is an equilibrium constant for the formation of a complex ion from its central metal ion and attached ligands. It quantifies the stability of the complex in solution.

5 Must Know Facts For Your Next Test

1. The higher the $K_f$ value, the more stable the complex ion.
2. $K_f$ is determined by the concentration of products over reactants in a balanced chemical equation for complex formation.
3. A large $K_f$ indicates that the formation reaction strongly favors product formation.
4. $K_f$ values are usually very large, often ranging from $10^6$ to $10^{30}$, indicating highly stable complexes.
5. The units of $K_f$ depend on the stoichiometry of the reaction and can vary.

Review Questions

Related terms

Complex Ion:

A charged species consisting of a central metal ion bonded to one or more ligands.

Ligand:

An ion or molecule that binds to a central metal atom to form a coordination complex.

Equilibrium Constant ($K_{eq}$): A numerical value that expresses the ratio of concentrations of products to reactants at equilibrium for any reversible chemical reaction.