Here’s a explanation of the role of complex formation in solubility:
1. Complex Formation
- Sometimes a solute can react with another species in the solution to form a complex ion or complex molecule.
- This new complex is often more soluble than the original solute.
2. How It Affects Solubility
- Normally, a salt might be sparingly soluble in water.
- If it forms a stable complex with a ligand (like ammonia or cyanide ions), the solute can dissolve much more, because the complex removes ions from solution and shifts equilibrium toward dissolving more solute.
Example:
- Silver chloride (AgCl) is almost insoluble in water.
- If ammonia (NH₃) is added, it forms [Ag(NH₃)₂]⁺, a soluble complex.
- This increases the solubility of AgCl in water.
3. In short:
Complex formation can increase solubility by stabilizing the dissolved ions, allowing more solute to dissolve.