nonsoluble

Nonsoluble is an adjective used to describe a substance that does not dissolve in a given solvent, or dissolves only to an extremely small extent. In everyday and scientific usage, it is often contrasted with soluble and sparingly soluble. A substance described as nonsoluble in water is effectively insoluble in water under ordinary conditions, though the term does not guarantee zero dissolution at all temperatures or concentrations.

Solubility depends on the interactions between solute particles and solvent molecules, as well as on factors such as temperature, pressure (for gases), and the chemical nature of the substances involved. For many solids dissolving in liquids, solubility generally increases with temperature, though there are notable exceptions. The concept of a solubility product constant (Ksp) helps quantify whether a solid will dissolve to form a saturated solution; when the product of ion concentrations exceeds Ksp, the solid tends to precipitate, reinforcing its nonsolubility under those conditions.

Common examples of substances regarded as nonsoluble in water include certain inorganic salts such as silver chloride (AgCl), barium sulfate (BaSO4), and lead(II) sulfate (PbSO4). Some materials are inherently insoluble due to strong lattice energies or lack of favorable interactions with water. Conversely, many organic compounds or salts may be sparingly soluble or soluble only in nonpolar solvents.

In practical contexts, nonsolubility affects fields from chemistry and environmental science to pharmacology. Poor aqueous solubility can limit drug bioavailability, driving research into methods to improve solubility, such as salt formation, use of co-solvents, particle size reduction, or solid dispersion. Overall, nonsolubility describes a key property that helps predict and explain the behavior of substances in solution.