Intermediate Topic 621 of 1102 Inorganic Chemistry
Hydrogen Peroxide
H2O2 acts as both oxidizing and reducing agent and decomposes to water and oxygen.
In-depth explanation of Hydrogen Peroxide
Hydrogen peroxide, H2O2, has oxygen in the -1 oxidation state, intermediate between water (-2) and O2 (0). It can act as an oxidizing agent, being reduced to water, or as a reducing agent, being oxidized to oxygen gas. The molecule is non-planar, with a skewed structure. It decomposes slowly, 2H2O2 giving 2H2O + O2, and the decomposition is catalysed by MnO2, by the enzyme catalase and by traces of metal ions, which is why it is stored in dark bottles with stabilizers. Dilute solutions of about 3 to 30 percent are used for bleaching and for disinfecting wounds.
Going deeper: Hydrogen Peroxide
Key ideas: H2O2 disproportionates: 2H2O2 gives 2H2O + O2, catalyzed by MnO2, iodide or light, so store in dark plastic bottles. It is an oxidant in acid (E0 = +1.78 V to water) and a reductant toward strong oxidants like KMnO4. Strength is quoted as volume strength: 20 volume means 1 mL releases 20 mL O2 at STP; molarity is about volume strength divided by 11.2.
Common mistakes and connections: Students treat H2O2 only as an oxidizer; with permanganate it releases O2 as the reducer. Oxidation state of oxygen is -1, not -2, an intermediate state allowing both behaviors. The molecule is nonplanar, with an open-book shape and dihedral angle near 111 degrees. Links to redox balancing and ozone.
Visualization of Hydrogen Peroxide
The skewed, non-planar H2O2 molecule with its weak O-O bond; oxygen sits at -1, so it can be oxidized to O2 or reduced to water. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Adding a spatula of MnO2 to 3 percent H2O2 produces a rapid fizz of oxygen gas.
Frequently asked questions about Hydrogen Peroxide
What is Hydrogen Peroxide?
H2O2 acts as both oxidizing and reducing agent and decomposes to water and oxygen.
Is Hydrogen Peroxide a beginner, intermediate or advanced topic?
Hydrogen Peroxide is a intermediate topic in Inorganic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Hydrogen Peroxide?
Study these earlier topics in Inorganic Chemistry first: Hydrides, Water Chemistry, Heavy Water.
What comes after Hydrogen Peroxide?
The next topics in Inorganic Chemistry are Alkali Metals and Reaction of Alkali Metals with Water.
Can I practise Hydrogen Peroxide with quizzes?
Yes. The interactive lesson includes a self-check question on Hydrogen Peroxide, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Hydrogen Peroxide fits in Inorganic Chemistry
Hydrogen Peroxide is topic 6 of 113 in Inorganic Chemistry.