How is a "solution" best defined in chemistry?

A "solution" in chemistry is best defined as a homogeneous mixture composed of a solute dissolved in a solvent. This definition highlights two essential components of a solution: the solute, which is the substance that is dissolved (often in smaller amounts), and the solvent, which is the substance that does the dissolving (usually in larger amounts).

The homogeneity of a solution means that the composition is uniform throughout; every part of the solution has the same properties and concentrations of solute. For example, when salt is dissolved in water, the salt particles spread evenly throughout the water, resulting in a consistent saline solution. This characteristic distinguishes solutions from heterogeneous mixtures, where different components can be easily distinguished and separated.

In contrast, a heterogeneous mixture consists of various substances that can be seen separately, like a salad or a mixture of sand and iron filings. The presence of only one type of particle defines a pure substance rather than a solution. Lastly, while some solutions may indeed conduct electricity (such as saltwater), this is not a defining characteristic of all solutions, nor does it pertain to the fundamental definition of what constitutes a solution.