Quantitative Analysis (Encyclopedia of Science)
The term quantitative analysis is used to described any procedure by which the percentage composition of any compound or mixture is determined. For example, chemists might want to know the exact composition of some new compound that has been discovered. Or they might want to find out what the percentage of gold is in a new ore that has been discovered. Both of these questions can be answered by the procedures of quantitative analysis. Quantitative techniques can be divided into two general categories: wet or classical techniques and instrumental methods.
Classical methods have been used since the beginning of modern chemistry in the nineteenth century. They generally make use of balances and calibrated glass containers to measure the percentage composition of a compound or mixture. For example, the procedure known as gravimetric analysis involves the addition of some chemical to the unknown compound or mixture to produce a precipitate. A precipitate is a solid formed during a chemical reactionsually in waterhat eventually settles out of the solution. In a gravimetric analysis, the precipitate is filtered, washed, dried, and weighed. The composition of the original unknown can then be calculated from the weights of the precipitate and sample and original unknown.
(The entire section is 656 words.)
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