Solubles

Solubles are substances that can dissolve in a solvent to form a homogeneous solution. Solubility, the extent to which a substance dissolves, depends on temperature, pressure (for gases), and the nature of the solvent and solute. The term is most often used in the context of liquids, particularly water, where many ionic or polar compounds dissolve readily.

Solubility is defined at a specific temperature in a given solvent and is limited by saturation. A saturated solution contains the maximum amount of solute that can dissolve under those conditions. Substances can be described as soluble, sparingly soluble, or insoluble based on how much dissolves. Relative solubility also depends on the solvent; a substance may dissolve well in one solvent but poorly in another (for example, salt is soluble in water but not in nonpolar solvents).

Common patterns in aqueous solubility include that most nitrates and acetates are soluble; most alkali metal salts and ammonium salts are soluble. Chlorides are generally soluble except for those of silver, lead, and mercury. Sulfates are soluble in many cases, but not with barium, strontium, and calcium to a limited extent. Carbonates and phosphates are typically insoluble except when paired with alkali metals or ammonium. These general guidelines help predict solubility, though exceptions exist.

Solubility is commonly expressed as grams of solute per 100 grams of solvent, or as molarity. For sparingly soluble compounds, the solubility product constant (Ksp) describes the equilibrium between solid and dissolved ions.

Factors influencing solubility include temperature (solids often become more soluble with higher temperature; gases become less soluble with higher temperature), pressure (gases become more soluble with increased pressure), solvent polarity, and the presence of other dissolved ions (common ion effect). Understanding solubility supports applications in chemistry, pharmacology, environmental science, and food science.