In chemistry, a homogeneous mixture of two or more substances in relative amounts that can vary continuously up to the limit of solubility ( saturation ), if any, of one in the other.
Most solutions are liquid s, but solutions also can be of gas es or solid s
for example, air (composed primarily of oxygen and nitrogen) or brass (composed chiefly of copper and zinc; see alloy ). In solutions comprising a solid dissolved in a liquid, the liquid is the solvent , and the solid is the solute; if both components are liquids, the one present in a smaller amount is usually considered the solute. If the saturation point is passed, excess solute separates out. Substances with ionic bond s (e.g., salt s) and many with covalent bond s (e.g., acid s, base s, alcohol s) undergo dissociation into ion s on dissolving and are called electrolyte s. Their solutions can conduct electricity and have other properties that differ from those of nonelectrolytes. Solutions are involved in most chemical reactions, refining and purification, industrial processing, and biological processes.