Contrast a heterogeneous mixture and a homogeneous mixture.

Mixture is a combination of two or more different
substances that have not combined chemically. Compounds can be contrasted from mixtures
as combination of two or more elements that have combined
chemically.

Homogeneity of a mixtures refers to the degree
of uniformity of composition. Mixtures vary in the degree of heterogeneity they possess,
from highly homogeneous to highly heterogeneous mixtures. All mixtures are heterogeneous
at molecular level. Similarly, a perfect heterogeneous mixture would require its
component substances to be completely separate from each other. A material like that
will not meet the basic definition of being combination of more than one material.
However mixtures in form of solution and gaseous forms, which are heterogeneous at
molecular level only are classified as homogeneous, while all other mixtures are
classified as heterogeneous mixtures. Some solutions when solidified also form
homogeneous mixtures.

One important difference between
homogeneous and heterogeneous mixtures is that components of homogeneous mixtures cannot
be separated by centrifugation, while those of heterogeneous mixtures can be
separated.

Moving from lowest homogeneity to higher
homogeneity the next level mixtures are colloidal solution. This is followed by followed
by dispersions.