The Uses of Volumetric Analysis

Chemistry flask
••• Image by Flickr.com, courtesy of Mi?osz

Volumetric analysis is a general term for a method in quantitative chemical analysis in which the amount of a substance is determined by the measurement of the volume that the substance occupies. It is commonly used to determine the unknown concentration of a known reactant. Volumetric analysis is often referred to as titration, a laboratory technique in which one substance of known concentration and volume is used to react with another substance of unknown concentration.

Introduction

Volumetric analysis was first introduced by Jean Baptiste Andre Dumas, a French chemist. He used it to determine the proportion of nitrogen combined with other elements in organic compounds, according to Encyclopedia Britannica. Dumas burned a sample of a compound with known weight in a furnace under conditions that ensured the conversion of all nitrogen into elemental nitrogen gas or N2.

History

In Dumas' experiment, the nitrogen from the furnace was then carried in a stream of carbon dioxide and passed into a strong alkali solution. The solution absorbed the carbon dioxide and allowed the nitrogen to accumulate in the tube. According to Britannica.com, the mass of the nitrogen was then calculated from the volume that it occupied under the known conditions of pressure and temperature. As a result, the proportion of nitrogen in the sample was determined.

Titration

Titration is the process of obtaining quantitative information from a given sample, according to the University of Waterloo, that involves a fast chemical reaction. When the reaction involves an acid and a base, the method is referred to as an acid-base titration. When the reaction involves oxidation and reduction, the method is referred to as a redox titration.

Uses

Volumetric analysis is used in high school and college chemistry labs to determine concentrations of unknown substances. The titrant (the known solution) is added to a known quantity of analyte (unknown solution) and a reaction takes place. Knowing the volume of the titrant allows the student to determine the concentration of the unknown substance. Medical labs and hospitals use automated titration equipment for basically the same purpose.

Examples

Volumetric analysis and titration are in wide use in a variety of industries because they are considered a basic technique in analytical chemistry. For example, titration can be used by the biodiesel industry to determine the acidity of a sample of vegetable oil. By knowing the precise amount of base that is needed to neutralize a sample of vegetable oil, scientists know how much base to add to neutralize the entire amount. Titration has similar uses in petrochemical and food industries. For example, an acid-titration may be used to determine free fatty acid content of an oil; a redox titration may be used to determine the amount of unsaturated fatty acids; and the Karl Fischer titration method may be used to analyze trace amounts of water found in a substance.

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