The Concentration reference article from the English Wikipedia on 24-Jul-2004
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Concentration

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Concentration is a measure of the amount of one specified element or component in a compound or mixture. Concentration may be expressed both qualitatively or quantitatively.

Qualitatively, terms such as dilute and concentrated are use to describe relatively low and high concentrations, respectively. Quantitatively, there are a number of different ways to express the ratio of the part to the whole. The most common are: