Views: 37
Introduction To Titrimetric Analysis
Titrimetric analysis refers to quantitative chemical analysis carried out by determining the volume of a solution of accurately known concentration which is required to react quantitatively with a measured volume of a solution of the substance to be determined. The solution of accurately known strength is called the standard solution.
Volumetric Analysis
Volumetric is one of the most commonly employed techniques in wet analysis. Many routine analyses of wastewaters, potable waters, and aqueous extracts of sludges and soils can be effectively performed using various titrimetric techniques.
In general, any titrimetric procedure involves the slow addition of a solution of accurately known concentration (a standard solution) to a solution of unknown concentration (sample to be analyzed) until the reaction between both the solutions is complete. In other words, the standard titrant is added slowly up to the point known as the end point at which the solute analyte in the sample is completely consumed by the solute in the standard solution. The completion of the reaction is usually monitored by using an indicator that causes a color change at the end point.
In titrimetric analysis the reagent of known concentration is called the titrant and the substance being titrated is termed the titrand.
The standard solution is usually added from a long graduated tube called a burette. The process of adding the standard solution until the reaction is just complete is termed a titration, and the substance to be determined is titrated. The point at which this occurs is called the equivalence point or the theoretical (or stoichiometric) end point. The completion of the titration is detected by some physical change, produced by the standard solution itself (e.g. the faint pink colour formed by potassium permanganate) or, more usually, by the addition of an auxiliary reagent, known as an indicator; alternatively some other physical measurement may be used.
After the reaction between the substance and the standard solution is practically complete, the indicator should give a clear visual change (either a colour change or the formation of turbidity) in the liquid being titrated. The point at which this occurs is called the end point of the titration. In the ideal titration the visible end point will coincide with the stoichiometric or theoretical end point. In practice, however, a very small difference usually occurs; this represents the titration error. The indicator and the experimental conditions should be selected so that the difference between the visible end point and the equivalence point is as small as possible.