Potentiometric Titration of Hydrogen Peroxide

Recommended for grades 9–12.

Figure from experiment 32 from Advanced Chemistry with Vernier

Introduction

One method of determining the concentration of a hydrogen peroxide, H₂O₂, solution is by titration with a solution of potassium permanganate, KMnO₄, of known concentration. The reaction is oxidation-reduction and proceeds as shown below, in net ionic form.

${\text{5 }}{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{2}}}{\text{ (aq) + 2 Mn}}{{\text{O}}_{\text{4}}}^{{\text{ - }}}{\text{ (aq) + 6 }}{{\text{H}}^{{\text{ + }}}}{\text{ (aq)}} \to {\text{ 5 }}{{\text{O}}_{\text{2}}}{\text{ (g) + 2 M}}{{\text{n}}^{{\text{2 + }}}}{\text{ (aq) + 8 }}{{\text{H}}_{\text{2}}}{\text{O (l)}}$

In this experiment, you will use an ORP (Oxidation-Reduction Potential) Sensor to measure the potential of the reaction. Your data will look like an acid-base titration curve. The volume of KMnO₄ titrant used at the equivalence point will be used to determine the concentration of the H₂O₂ solution. Your sample of H₂O₂ will come from a bottle of ordinary, over-the-counter hydrogen peroxide purchased at a grocery or a drug store. The concentration of this product is labeled as 3% mass/volume, which is ~0.9 M.

Objectives

In this experiment, you will

Conduct the potentiometric titration of the reaction between commercially available hydrogen peroxide and potassium permanganate.
Measure the potential change of the reaction.
Determine the concentration of the hydrogen peroxide solution.

Sensors and Equipment

This experiment requires each of the following Vernier sensors and equipment (unless otherwise noted):

ORP Sensor
Drop Counter (optional)

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

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The student-version preview includes:

Step-by-step instructions for computer-based data collection
List of materials and equipment

Note: The experiment preview of the computer edition does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.

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