9.25 What is meant by stability of a coordination compound in solution? State the factors which govern stability of complexes.

The stability of a complex in a solution refers to the degree of association between the two species involved in a state of equilibrium. Stability can be expressed quantitatively in terms  of stability constant or formation constant. 
M + 3L  ML3
Stability constant, β = ML3ML3
For this reaction, the greater the value of the stability constant, the greater is the proportion of ML3 in the solution.
Stability can be of two types:
(a) Thermodynamic stability:
The extent to which the complex will be formed or will be transformed into another species at the point of equilibrium is determined by thermodynamic stability.

(b) Kinetic stability:
This helps in determining the speed with which the transformation will occur to attain the state of equilibrium.
Factors that affect the stability of a complex are:
(a) Charge on the central metal ion: Thegreater the charge on the central metal ion,the greater is the stability of the complex.
2. Basic nature of the ligand: A more basic ligand will form a more stable complex.
2. Presence of chelate rings: Chelation increases the stability of complexes.