Redox Titration

Potentiometric Determination of Peroxides: A Precise Approach

Peroxides, characterized by their unique oxygen-oxygen bond (O-O), are employed in diverse applications, ranging from industrial bleaching processes to disinfection. Precise quantification of their concentration is critical for ensuring effectiveness and safety. This page explores the application of potentiometric titration as a powerful analytical technique, for the determination of peroxides. 

The Automated Advantage: Utilizing the Titrator

The titrator automates the analysis by precisely dispensing a titrant solution in minute increments while continuously monitoring the potential of the solution. This data is then meticulously plotted as a titration curve, where the potential is represented on the y-axis and the corresponding titrant volume on the x-axis. 

Untangling the Curve: Unveiling Peroxide Concentration

The key to unlocking the peroxide concentration lies within the equivalence point. This specific point on the titration curve signifies the complete reaction of the analyte (peroxide) with the titrant. It manifests as a distinct inflection point, characterized by a significant shift in the slope of the curve. By meticulously analyzing the volume of titrant utilized at this point, the initial concentration of the peroxide can be accurately calculated.

Choosing the Titrant

The selection of the titrant employed in the determination of peroxides hinges on the specific approach chosen. Two primary approaches prevail:

1. Titrant Selection:

• • Direct Oxidation: For peroxides that readily undergo oxidation, a strong oxidizing agent like potassium permanganate (KMnO4) .

  • Indirect Iodometric Titration: This approach involves the addition of an excess of potassium iodide (KI) to the sample solution. The peroxide in the sample acts as an oxidizing agent, converting the iodide to iodine (I2). The liberated iodine is then titrated with a standardized solution of sodium thiosulfate (Na2S2O3). 

  • This approach is particularly beneficial for peroxides that exhibit lower oxidation potential. 

• Electrode Selection: Platinum electrodes are preferred due to their wide potential window and catalytic properties for certain redox reactions.