Are compounds considered pure substances?

1 Answer
May 2, 2014

Compounds are classified as pure compounds.

To understand this it is helpful to know how matter is classified from general to specific categories.
One approach to classification separates matter into mixtures and pure substances.

Mixtures are composed of substances that are physically combined. For example dirt is a heterogenous mixture because it is composed of particles of differing sizes while solutions are homogenous mixtures composed of solute and solvent.

Salt water is an example of this since the solute (salt) is evenly distributed throughout the dissolving medium which is the solvent.

Pure substances, on the other hand, are joined chemically .
Water , a compound, is composed of two different elements, an oxygen chemically bonded to two hydrogen atoms.

Elements are also classified as pure substances since they are made of only one type of atom. The noble gases which normally do not form chemical bonds are pure substances. Hydrogen gas is a pure substance made of two hydrogen