Editing Hydrogen peroxide (section)

==Reactions==
===Acid-base===
Hydrogen peroxide is about 1000 times stronger as an acid than water.<ref>{{Greenwood&Earnshaw2nd|page=633-637}}</ref>
:{{chem2|H2O2 <-> H+ + HO2-}} (p''K'' = 11.65)

===Disproportionation===
Hydrogen peroxide disproportionates to form water and oxygen with a [[Standard enthalpy change of reaction|Δ''H''<sup><s>o</s></sup>]] of −2884.5&nbsp;[[Kilojoule|kJ]]/[[Kilogram|kg]]<ref>{{Cite web|url=https://www.proakademia.eu/gfx/baza_wiedzy/461/nr_26_45-52_2_3.pdf|title=Decomposition of Hydrogen Peroxide — Kinetics and Review of Chosen Catalysts|access-date=30 August 2019|archive-url=https://web.archive.org/web/20181222153038/https://www.proakademia.eu/gfx/baza_wiedzy/461/nr_26_45-52_2_3.pdf|archive-date=22 December 2018|url-status=live}}</ref> and a Δ[[Entropy|S]] of 70.5&nbsp;J/(mol·K):

:{{chem2| 2 H2O2 -> 2 H2O + O2 }}

The rate of decomposition increases with rise in temperature, concentration, and [[pH]]. {{chem2|H2O2}} is unstable under alkaline conditions. Decomposition is catalysed by various redox-active ions or compounds, including most [[transition metal]]s and their compounds (e.g. [[manganese dioxide]] ({{chem2|MnO2}}), [[silver]], and [[platinum]]).<ref>{{cite book |vauthors = Petrucci RH |date=2007 |title=General Chemistry: Principles & Modern Applications |edition=9th |publisher=Prentice Hall |isbn=978-0-13-149330-8 |page=[https://archive.org/details/generalchemistry0000petr/page/606 606] |url=https://archive.org/details/generalchemistry0000petr/page/606}}</ref>

===Oxidation reactions===
The [[redox]] properties of hydrogen peroxide depend on pH. In acidic solutions, {{chem2|H2O2}} is a powerful [[oxidizer]].
{| class="wikitable"
|-style="vertical-align: top;"
![[Oxidant|Oxidizing<br>reagent]] !!Reduced<br>product
! [[Oxidation potential|Oxidation<br>potential]]<br>(V)
|-
| [[fluorine|{{chem2|F2}}]]||[[Hydrogen fluoride|HF]]
| align="center"|3.0
|-
| [[ozone|{{chem2|O3}}]]||[[Oxygen|{{chem2|O2}}]]
| align="center"|2.1
|-
| {{chem2|H2O2}}||[[Water|{{chem2|H2O}}]]
| align="center"|1.8
|-
| [[potassium permanganate|{{chem2|KMnO4}}]]||[[manganese dioxide|{{chem2|MnO2}}]]
| align="center"|1.7
|-
| [[chlorine dioxide|{{chem2|ClO2}}]]||[[Hypochlorous acid|HClO]]
| align="center"|1.5
|-
| [[chlorine|{{chem2|Cl2}}]]||[[Chloride|{{chem2|Cl−}}]]
| align="center"|1.4
|}

[[Sulfite]] ({{chem2|SO3(2−)}}) is oxidized to [[sulfate]] ({{chem2|SO4(2−)}}).

===Reduction reactions===
Under [[alkaline]] conditions, hydrogen peroxide is a reductant. When {{chem2|H2O2}} acts as a reducing agent, [[oxygen]] gas is also produced. For example, hydrogen peroxide will reduce [[sodium hypochlorite]] and [[potassium permanganate]], which is a convenient method for preparing [[oxygen]] in the laboratory:
:{{chem2|NaOCl + H2O2 -> O2 + NaCl + H2O}}
:{{chem2|2 KMnO4 + 3 H2O2 -> 2 MnO2 + 2 KOH + 2 H2O + 3 O2}}

The oxygen produced from hydrogen peroxide and sodium [[hypochlorite]] is in [[singlet oxygen|the singlet state]].

Hydrogen peroxide also reduces [[silver oxide]] to [[silver]]:
:{{chem2|Ag2O + H2O2 -> 2 Ag + H2O + O2}}
Although usually a reductant, alkaline hydrogen peroxide converts Mn(II) to the dioxide:
:{{chem2|H2O2 + Mn(2+) + 2 OH- -> MnO2 + 2 H2O}}

In a related reaction, [[potassium permanganate]] is reduced to {{chem2|Mn(2+)}} by ''acidic'' {{chem2|H2O2}}:<ref name=House/>
:{{chem2|2 MnO4- + 5 H2O2 + 6 H+ -> 2 Mn^{2+} + 8 H2O + 5 O2}}

===Organic reactions===
Hydrogen peroxide is frequently used as an [[Redox|oxidizing agent]]. Illustrative is oxidation of [[thioether]]s to form [[sulfoxide]]s, such as conversion of [[thioanisole]] to [[methyl phenyl sulfoxide]]:<ref>{{cite journal |vauthors = Ravikumar KS, Kesavan V, Crousse B, Bonnet-Delpon D, Bégué JP |year = 2003 |title = Mild and Selective Oxidation of Sulfur Compounds in Trifluoroethanol: Diphenyldisulfide and Methyl phenyl Sulfoxide |journal = Org. Synth. |volume = 80 |page = 184 |doi = 10.15227/orgsyn.080.0184}}</ref><ref>{{Cite journal |vauthors = Xu WL, Li YZ, Zhang QS, Zhu HS |title = A Selective, Convenient, and Efficient Conversion of Sulfides to Sulfoxides |doi = 10.1055/s-2004-44387 |journal = Synthesis |issue = 2 |pages = 227–232 |year = 2004}}</ref>
:{{chem2| Ph\-S\-CH3 + H2O2 -> Ph\-S(O)\-CH3 + H2O }}

Alkaline hydrogen peroxide is used for [[epoxidation]] of electron-deficient alkenes such as [[acrylic acid]] derivatives,<ref>{{cite journal |vauthors = Mayer RJ, Ofial AR |title = Nucleophilic Reactivities of Bleach Reagents |journal = Organic Letters |volume = 20 |issue = 10 |pages = 2816–20 |date = May 2018 |pmid = 29741385 |doi = 10.1021/acs.orglett.8b00645}}</ref> and for the oxidation of [[alkylborane]]s to [[ethanol|alcohol]]s, the second step of [[hydroboration-oxidation]]. It is also the principal reagent in the [[Dakin oxidation]] process.

===Precursor to other peroxide compounds===
Hydrogen peroxide is a weak acid, forming [[hydroperoxide]] or [[peroxide]] [[Salt (chemistry)|salts]] with many metals.

It also converts metal oxides into the corresponding peroxides. For example, upon treatment with hydrogen peroxide, [[chromic acid]] ({{chem2|CrO3}} and {{chem2|H2SO4}}) forms a blue peroxide [[Chromium(VI) oxide peroxide|{{chem2|CrO(O2)2}}]].