Heterogeneous and homogeneous mixtures are identified by the level at which the mixtures blend together. Visible indications of different components within a mixture denote a heterogeneous mixture, while a uniform, single-component appearance indicates a homogeneous mixture.
Heterogeneous mixtures are those that do not blend together completely, with one of the most common examples being a mixture of oil and water. Neither of the components dissolve to form a uniform solution, and this result is clearly visible as the components separate. Another great example of a heterogeneous mixture is a pile of rocks. While the pile itself may be a collection of the same type of rock, the different components, individual rocks, are clearly visible.
Homogeneous mixtures, on the other hand, appear as a single, cohesive solution. Sugar dissolved in water is an example of a common homogeneous mixture. When completely dissolved, the substance appears to be one component. However, homogeneous mixtures can become saturated, resulting in a heterogeneous mixture. For example, there is a point at which no more sugar is dissolved into a glass of water, resulting in saturation. At this point, any additional sugar added is no longer dissolved and is readily visible, changing the state of the mixture.