Solubility refers to the ability of a substance to dissolve in a particular solvent to form a homogenous solution. A substance that is soluble can be completely dissolved in the solvent, while an insoluble substance cannot be dissolved or can only dissolve to a negligible extent. Solubility is determined by a number of factors, including temperature, pressure, and the chemical nature of the solvent and solute.

Temperature plays an important role in determining solubility. Generally, as the temperature of a solvent increases, the solubility of a solute in that solvent also increases. This relationship holds true for most, but not all solutes. Some solutes exhibit a decrease in solubility as temperature increases, and some exhibit no change.

Pressure can also affect solubility, but typically only for gases. As pressure increases, the solubility of a gas in a liquid increases. This is why carbonated beverages become less bubbly when opened at higher altitudes, where the atmospheric pressure is lower.

The chemical nature of the solvent and solute can also play a significant role in determining solubility. For example, polar solvents like water are typically effective at dissolving polar solutes, while nonpolar solvents like gasoline are effective at dissolving nonpolar solutes. However, there are some exceptions, and there are solvents that can dissolve both polar and nonpolar solutes, such as ethanol.

Solubility has many practical applications, including in pharmaceuticals, chemistry, and environmental science. It can be used in the synthesis of drugs, the purification of chemicals, and the removal of pollutants from water.