Preparation:
Industrially, hydrogen peroxide is prepared by the anthraquinone process, where anthraquinone is hydrogenated to form anthrahydroquinone, which reacts with oxygen to produce hydrogen peroxide:
C6H4(CO)2(CH2)2 + H2 → C6H4(COH)2(CH2)2
C6H4(COH)2(CH2)2 + O2 → C6H4(CO)2(CH2)2+H2O2
Properties:
Colorless liquid with a slightly sharp odor.
Miscible with water in all proportions.
Acts as a weak acid and strong oxidizing agent.
Typically, available as a 3% solution for medicinal use.
Chemical formula: H₂O₂.
Uses:
As an antiseptic for cleaning wounds to prevent infection.
As an oral rinse for mouth ulcers and gingivitis.
In higher concentrations, used for sterilizing medical equipment.
As a bleaching agent in the cosmetic industry.
Storage of Hydrogen Peroxide:
Store in a cool, dark place, away from light and heat to prevent decomposition.
Keep in a well-sealed, non-metallic container, typically brown or opaque to protect from light.
Assay of Hydrogen Peroxide (H₂O₂)
Purpose:
To determine the concentration or purity of hydrogen peroxide using permanganate titration.
Procedure:
1. Prepare a Standard Solution:
Dissolve a known amount of potassium permanganate (KMnO₄) in water to create a solution of known concentration.
2. Prepare the H₂O₂ Sample:
Dilute an accurate volume of the H₂O₂ sample with water, as concentrated H₂O₂ can be hazardous.
3. Add Acid:
Add a known volume of sulfuric acid (H₂SO₄) to the diluted H₂O₂ sample to create an acidic environment for the reaction.
4. Titrate:
Slowly add the KMnO₄ solution to the acidic H₂O₂ solution while stirring.
The reaction between H₂O₂ and KMnO₄ occurs as follows:
The endpoint is reached when the pink color of KMnO₄ persists, indicating that all the H₂O₂ has reacted.
5. Calculate the Concentration:
Measure the volume of KMnO₄ solution used in the titration.
Use the stoichiometry of the reaction to calculate the concentration or purity of the H₂O₂ sample.