The purpose of titration is to determine the concentration of a substance (analyte) by gradually adding a titrant until there is a specific chemical reaction. The titrant is a standard solution of known concentration used as the control and is added using a burette. The reaction occurs at the “equivalence point”, the point at which the solutions are chemically eqivalent. So we can say that at the point of reaction, X quantity of chemical A is equivalent to Y quantity of chemical B. The reaction is often characterised by a change in colour.
Advantages of Titration
Titration (also known as volumetric analysis or titrimetric analysis) has several advantages against gravimetric methods:
1. Speed of analysis – Reactions complete instantaneously so a positive assessment can be made very quickly.
2. Greater accuracy – There is no material loss through decanting (material being transferred from one container to another) as the process takes place in one container only, with accurately dispensed titrant being added. Filtration is not required so there are no losses from that either.
Methods of Titration
1. Karl Fischer titration
Karl Fischer titration was invented in the 1930s by Karl Fischer, a German chemist. This classic titration chemical analysis method uses volumetric titration (also known as coulometric titration) to calculate trace elements of water contained in a sample solution.
2. Potentiometric titration
Potentiometric titration measures the change of electrical potential at the end point of the titration using an indicator electrode. The change of the potential is a function of the volume of titrant added to the solution.
Types of titration
1. Acid-base Titration
Acid-base titration is used to work out the concentration of an acid or base. It is carried out by a chemical experiment which has the purpose of precisely neutralizing the acid or base being analyzed. If the solution is an acid, an alkali (base) is added until the solution becomes chemically neutral at pH 7. The concentration of the acid can therefore be determined as the concentration of the base is a known value, as are the volumes of acid and base.
The video below explains acid-base titration in simple terms
2. Redox Titration
Redox Titration is a method used in a science laboratory to find the concentration of an analyte. An oxidation-reduction reaction between the analyte and the titrant is instigated, from which the concentration of the analytre is determined. This reaction is known as redox titration.
There are various different types of redox titration; Iodimetry analyzes the iodine released in a chemical reaction, Ceremetry is a redox titration where a ferroin color change during volumetric chemical analysis indicates the end point of the reaction, Permanganometry uses potassium permanganate as an indicator to determine the endpoint of a redox titration. Other tyes include Potassium iodate and potassium dichromate titrations.
3. Precipitation Titration
Precipitation titration is known as a “titrimetric method” in which the analyte and titrant react to form an insoluble precipitate substance. The reaction ends when all of the analyte has reacted.
4. Complexometric Titration
In complexometric titration volumetric analysis, the endpoint of the titration is indicated by a colored complex formation. As it is a visual indication, the color change must be clear and definite so the indicator used in the process detects the end point of the titration.