Solvent

•The component present in largest quantity

•When water is the solvent, the homogenous mixture solution is referred as aqueous

–Latin aqua = water

It is the concentration of solute in a saturated solution at a certain temperature.

in a qualitative way:

It is the spontaneous interaction of two

or more substances (solute & solvent) to form a homogeneous molecular dispersion.

Solubility expressions

a) The solubility of a drug can be expressed in terms of:

- Molarity

- Normality

- Molality

- Mole fraction

- percentage (% w/w, % w/v, % v/v).