Humber Admissions Practice Test

What defines a solution in chemistry?

1. A heterogeneous mixture

2. A homogeneous mixture

3. A pure substance

4. Any mixture of solids

The correct answer is: A homogeneous mixture

A solution in chemistry is defined as a homogeneous mixture, which means that the composition is uniform throughout the mixture. In a solution, the solute (the substance being dissolved) is evenly distributed within the solvent (the substance doing the dissolving), resulting in a consistent phase and appearance. This uniformity distinguishes solutions from heterogeneous mixtures, where the components remain distinct and can usually be seen as separate parts. The definition highlights that, in a solution, you cannot identify individual components by visual inspection, as they are intertwined at a molecular level. This is why the choice that specifies a homogeneous mixture is the most accurate representation of a solution. Additionally, pure substances, although they may be solutions in themselves when involving a single chemical compound, do not fit the general definition of a solution as they do not involve a mixture. Lastly, the option that includes mixtures of solids does not conform to the typical definition of a solution, as solutions often involve liquids and can be composed of solutes in a liquid solvent, distinguishing them from solid-only mixtures.