2.19: Classification of Titrimetric Analysis Based on Reaction Types
Titrimetric analysis in solution chemistry involves measuring the volume of solutions and is often called volumetric analysis. The standard solution of known concentration in the burette is called the titrant, whereas the solution of unknown concentration in the flask is called the analyte, or titrand. Titrimetric analyses can be classified into four types based on the reactions between the titrant and analyte.
Titrations between an acid and a base lead to neutralization reactions that form water molecules. This is called an acid-base titration. For example, the titration of a sodium hydroxide standard solution with the analyte hydrochloric acid generates water, leaving behind the acidically neutral sodium and chloride ions. In the second type of titrimetric analysis – complexometric titrations, metal ions such as silver and mercury come together with electron donors such as cyanide and chloride to form complexes. The third type is precipitation titration, in which the titrant reacts with the analyte to form an insoluble product. For instance, the titration between chloride ion and silver nitrate solution will produce the insoluble silver chloride. In the last type of titrimetric analysis, redox reactions are used to determine the amount or concentration of an analyte. In this case, the oxidation states of the titrant and the analyte change as a result of electron transference between the two. The standard solution can be an oxidizing or a reducing agent, and the end point can be detected with indicators or changes in the electrical signals.
