Solution

A solution is a homogeneous mixture formed when a solute is dissolved in a solvent, yielding a single phase with uniform composition. The solute is the substance present in lesser amount, while the solvent is the component present in greater amount. Solutions can be liquids, solids, or gases.

In chemistry, dissolution involves interactions between solute particles and solvent molecules, producing a stable mixture where the components are not distinguishable by appearance. Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a stated temperature and pressure. Temperature and solvent polarity influence solubility; for gases, increasing pressure often raises solubility in liquids.

Concentration describes how much solute is in a solution and is commonly expressed as molarity (moles per liter), molality (moles per kilogram of solvent), mole fraction, or mass percent. Solutions are often categorized as aqueous when the solvent is water, or non-aqueous otherwise. They can be unsaturated, saturated, or supersaturated depending on the relative amount of dissolved solute.

In other disciplines, the term solution also denotes the answer to a problem or the method used to obtain it. In mathematics, a solution set comprises all elements that satisfy a given equation or condition.

Practical applications span chemistry, biology, medicine, environmental science, and industry, including drug formulations, analytical testing, nutrient delivery, and water treatment. The study of solutions covers solvation, diffusion, and colligative properties, which depend on solute concentration.