Determination of concentration of KMnO4 solution

Determination of concentration of KMnO₄ solution

• 
  
• 
  

Quantitative Analysis

Objective

Our objective is to determine the strength of KMnO4 solution by titrating it against a standard solution of;

• Oxalic acid
• Ferrous ammonium sulphate (Mohr’s salt)

The Theory

What is Titration?

Titration is a common laboratory method of qualitative chemical analysis that can be used to determine the unknown concentration of a solution (analyte). The basis of this process is the reaction between the analyte and a solution of unknown concentration (standard solution). The analyte is taken in a conical flask using a pipette and the solution of known concentration is taken in a calibrated burette (titrant).

Some Important Terms in Titration

1. Standard solution

A solution whose concentration is known, is called a standard solution. The substance used to prepare a standard solution is called the primary standard. Oxalic acid and sodium carbonate are some examples.

2. Concentration of a solution

Concentration of a solution is defined as the amount of a solute present in a definite volume of the solvent. Concentration of a solution can be expressed in different ways.

• Normality: Normality of a solution is defined as the number of gram equivalent of solute per litre of the solution. It is denoted by ‘N’.

 

• Molarity: Molarity of a solution is defined as the number of gram moles of the solute per litre of the solution. It is denoted by ‘M’.

3. End point of a titration

The endpoint of a titration is the point at which the reaction between the titrant and the analyte becomes complete. Generally the endpoint of a titration is determined using indicators. In some cases, either the reactant or the product can serve as the indicator. A best example is the redox titration using potassium permanganate.

Titrations can be classified as:

• Acid-Base Titrations or Acidimetry and Alkalimetry
• Oxidation-Reduction Titrations or Redox Titrations
• Precipitation Titrations
• Complexometric Titrations

We will learn about Redox titrations.