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Glossary:

  • Pure Substance

A single element or compound that is not mixed with any other substance.

  • Melting Point

The melting point of a substance is the temperature at which it changes state from solid to liquid.

  • Boiling point

The boiling point of a substance is the temperature at which it changes state from liquid to gas.

Atom

The smallest part of an element that can exist.

  • Element

A substance made of one type of atom only.

  • Mixture

Consists of two or more different substances, not chemically joined together.

  • Compound

Contains two or more types of atom joined together.

  • Formulation

A mixture that has been designed as a useful product.

e.g. medicine, paint.

  • Chromatography

A technique that can be used to separate mixtures and identify substances.

  • Solvent

The liquid in which the solute dissolves to form a solution.

compound.

  • Soluble

Able to dissolve in solvent.

  • Mobile phase

Phase in chromatography that moves, usually a solvent or mixture of solvents.

  • Stationary phase

Phase in chromatography that does not move, for instance, the paper in chromatography.

  • RF (Retention Factor)

A measurement from chromatography:

The ratio of the distance moved by a compound to the distance moved by solvent.

Chromatography

C8: Chemical Analysis

Chromatography can be used to separate mixtures and help identify substances.

It involves a mobile phase (e.g. water or ethanol) and a stationary phase (e.g. chromatography paper).

The Rf value is calculated using:

Rf values vary from 0 to 1

Rf = distance moved by substance

distance moved by solvent

Gas Tests

Testing for Oxygen

Testing for Hydrogen

Testing for Carbon Dioxide

Testing for Chlorine