A redox titration is a form of titration established on a redox reaction between the titrant and analyte. Redox titration can involve the use of a redox indicator or a potentiometer. A general example of a redox titration is treating a solution of iodine with a reducing agent to create iodide using a starch indicator to help spot the endpoint. Iodine (I2) can be reduced to iodide (I−) example. thiosulfate (S2O32−), when all iodine is consumed the blue color vanishes. This is process is known as an iodometric titration.
It is an oxidizing agent in this kind of redox titration method. Maintenance of the mixture is done with the help of dilute sulphuric acid. Moreover, the addition of Sulphuric acid also helps to raise the hydrogen ions present in the solution.
In this technique, potassium dichromate behaves as the oxidant in the acidic medium. It is essential to maintain the acidity of the medium by addition of dilute sulphuric acid. The equation of the reaction is
This is an exciting but simple method. In this case, free iodine reduction to iodide ions happens as well as iodine ion oxidation to free iodine occurs. The reduction and oxidation reactions are
Three kinds of indicators are needed to signal a redox titration’s end point. The reduced and oxidized forms of certain titrants, such as MnO4–, have different colors. A solution of MnO4– is strong purple. In an acidic solution, still, permanganate’s reduced form, Mn2+, is almost colorless. When using MnO4– as a titrant, the titrand’s mixture remains colorless till the equivalence point. The first drop of excess MnO4– produces a permanent tinge of purple, indicating the endpoint.
where Aox is the titrand’s oxidized state, and Bred is the titrant’s reduced state. The reaction’s potential, Erxn, is the difference among the reduction potentials for each half-reaction.
After every addition of titrant, the reaction between the titrand and the titrant touches a state of equilibrium. Due to the potential at equilibrium is zero, the titrand’s and the titrant’s reduction potentials are similar.
Another technique for finding a redox titration’s endpoint is with the help of potentiometric titration in which we observe the change in potential while adding the titrant to the titrant. The endpoint is seen by visually examining the titration curve. The common experimental design for a potentiometric titration contains a Pt indicator probe whose potential is controlled by the titrand’s or titrant’s redox half-reaction and a reference probe or electrode that has a permanent potential
Although several quantitative applications of redox titration have been substituted by other analytical methods, some important applications continue to be applicable. The general application of redox titration with an impact on environmental, pharmaceutical, and industrial applications.