Complexometric Titration
Complexometric titration, also known as chelatometry, is a volumetric analysis method that uses the formation of colored complexes to indicate the endpoint of a titration. The procedure consists of the following key aspects:
Preparation of Solutions:
- Prepare a solution of the analyte containing metal ions and a standard solution of the titrant, often ethylenediaminetetraacetic acid (EDTA).
- The EDTA forms complexes with metal ions in solution.
Titration Process:
- Add the EDTA titrant to the analyte solution containing metal ions until a color change occurs, indicating the formation of metal-EDTA complexes.
- The endpoint is reached when all metal ions have formed complexes with EDTA, leading to a distinct color change.
Calculating Analyte Concentration:
- Measure the volume of EDTA titrant used during the titration.
- Calculate the concentration of metal ions in the analyte based on the volume and known concentration of EDTA.
Use of Indicators:
- Complexometric indicators like Fast Sulphon Black, Eriochrome Black T, or Murexide are used to detect the endpoint by displacing them from metal cations in solution.
Example Result:
An example application involves determining total hardness in water using complexometric titration with EDTA. The process includes:
- Adding excess standard EDTA and back-titrating with standard Mg solution using an indicator like solochrome black to determine the sum of all metals present.
- Treating an aliquot portion with excess KCN to determine Mg only.
- Adding excess chloral hydrate to liberate Zn from the cyanide complex and titrating until the indicator turns blue to determine Zn content.
- The Cu content can then be calculated by difference.
Complexometric titrations are widely used for determining metal ion concentrations in various samples due to their accuracy and versatility. These methods are essential in industries like pharmaceuticals, cosmetics, and analytical chemistry for precise metal ion analysis.
Types of Titration
Titration is an important process in chemical analysis used to determine the quantity of a sample’s constituent by adding a known proportion of a standard solution. There are several types of titrations based on the nature of the chemical reaction between the sample and the titrant. In this article, we will see what is titration, its types, applications, and more.
Table of Content
- What is Titration?
- Types of Titration
- Acid-Base Titration
- Redox Titration
- Precipitation Titration
- Complexometric Titration