Titration
Titration is a type of quantitative chemical analysis. It is used to work out the unknown concentration of a known substance.
It makes the use of two main chemical apparatus namely, pipette and burette. External indicators like phenolphthalein or methyl orange and internal indicators like KMnO4 (potassium permanganate) are used to mark the end point of titration.
A known concentration and volume of a reagent, called the titrant or titrator, is added to a known volume of another reagent, the analyte or titrand. This is done slowly from a burette until the end point is reached. The volume added before the end point is reached is noted. Because one of the solutions, the titrant, has a known concentration, that of the other, the titrand, can be calculated.[1]
Professionals now use a pH meter, which is potentiometer with an electrode whose potential depends on the amount of H+ ions in the solution. The pH of the solution is measured throughout the titration, more accurately than with an indicator. At the endpoint there is a sudden change in the measured pH.
Since volume measurements play a key role in titration, it is known as volumetric analysis as well as quantitative analysis.
Titration Media
A burette and Erlenmeyer flask (conical flask) being used for an acid–base titration.
Analysis of soil samples by titration.
A typical titration curve of a diprotic acid titrated with a strong base. Shown here is oxalic acid titrated with sodium hydroxide. Both equivalence points are visible.
Titration methyl orange.
Phenolphthalein, a commonly used indicator in acid and base titration.
Color of iodometric titration mixture before (left) and after (right) the end point.
An elementary pH meter that can be used to monitor titration reactions.
A titration is demonstrated to secondary school students.
References
- ↑ Daintith, John, ed. (2008). A Dictionary of Chemistry (Sixth ed.). p. 530. ISBN 978-0-19-920463-2.