Chemistry – Chemical Analysis

In chemistry, a pure substance is a single element or compound — not mixed with anything else. A pure substance has a sharp, specific melting point. An impure substance (mixture) melts over a range of temperatures and has a lower melting point than the pure substance.

Mixtures can be separated by physical methods because no chemical bonds are broken. Common separation techniques include filtration, evaporation, distillation, and chromatography.