Experiment 4 Online Tutorial >> Volumetric Analysis: Potassium Permanganate Titration >> Introduction

Experiment 4 - Volumetric Analysis: Potassium Permanganate Titration

Introduction

In this experiment, your goal is to determine the concentration of unknown KMnO₄ using sodium oxalate of known concentration.

The experimental setup and strategy are shown below.

Step 1: Preparing a Sodium oxalate of known concentration What concentration do I want?       Determine the concentration of the oxalic acid for 25.00 mL of it to react completely with 25 mL of 0.01 M KMnO4 solution using the Calculate Concentration Oxalic Acid tutor on page 2. How do I make the solution?       See Connect EXP 4 Module on Making a Standard Solution. What glassware do I use?       See Connect EXP 4 module on Significant Figures & Volumetric Analysis.

Step 2: Performing the Titration

Add titrant until solution turns constant pale pink colour.

Why does it turn pink?
      Titration of KMnO₄ (purple) into the oxalate solution (colourless), produces colourless Mn²⁺ until the end point. At the end point, the oxalate solution will be exhausted and the purple solution colour will be permanent.

How do I interpret the results?
      When performing volumetric analysis calculations, consider how you will calculate the amount (number of moles) of KMnO₄ in solution. This experiment uses a known amount of sodium oxalate. From this amount, consider how you can determine the concentration of KMnO₄. Remember to consider the stoichiometry of this reaction in your calculations.

2MnO₄^- + 6H⁺ + 5H₂C₂O₄ --> 2Mn²⁺ + 8H₂O + 10CO₂

Practice this reaction in the Virtual Lab
      Perform a virtual titration of this problem using the ChemCollective Virtual Laboratory on page 4 of this tutorial.

The following pages contain tutors to assist you in the calculations required for the above steps. Please click next to continue to the tutors.