Chemical Analysis: Key Words

chromatogram

A graph that shows the result of separating the components of a mixture by chromatography.

chromatography

• A technique used to separate mixtures due to the distribution of the substances between the stationary and mobile phase.

• It can give information to help identify substances.

flame emission spectroscopy

An instrumental method used to analyze metal ions in solutions.

flame test

• Qualitative test used to identify metal ions (cations).

• Carried out by inserting a nichrome wire loop with the unknown compound on into a flame and observing the color.

formulation

• A mixture that has been designed as a useful product.

• They are made by mixing the components in carefully measured quantities to ensure that the product has the required properties.

impure substance

A substance made up of two or more elements or compounds that are not bonded together chemically.

instrumental methods

• Can be used to detect and identify elements and compounds.

• They are accurate, sensitive and rapid.

litmus paper

• Paper stained with litmus which can be used to indicate the acidity or alkalinity of a substance.

• Used in the test for chlorine.

mobile phase

Where the molecules can move during chromatography. It is always a liquid or gas.

precipitation

The creation of a solid from a solution.

pure substance

• In chemistry a pure substance is a single element or compound, not mixed with any other substance.

• In everyday language, a pure substance can mean a substance that has had nothing added to it, so it is unadulterated and in its natural state.

R_f value

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

stationary phase

Where the molecules are stationary during chromatography. It is a solid or a liquid supported on a solid.