Solubility

A solution is a homogeneous mixture of two main substances: the solute and the solvent. The solvent is present in greater quantity than the solute.

In a dilute solution, the proportion of solute relative to the solvent is small, whereas for a concentrated solution, the proportion is large.

When forming a solution, the solute and the solvent do not react chemically. Instead, the molecules redistribute, with individual solvent molecules surrounding the solute molecules and interacting through attractive forces. Such a dissolution process is called solvation.

To favor solvation, the solute–solvent interactions should be stronger than the solvent–solvent and solute–solute interactions.

In a solution, the solute and solvent can be any state of matter. The solution itself is a single “phase”.

The opposite of solvation is precipitation, triggered by strong solute–solute interactions. When the rate of solvation equals the rate of precipitation, a solubility equilibrium is established.

A solute’s solubility is its maximum possible concentration at solubility equilibrium in a given amount of solvent. Solubility is affected by temperature and other physical conditions like molecular polarity.