View source for Physics:Oxyhydrogen

{{short description|Explosive mixture of hydrogen and oxygen gases}}
[[Image:Electrolyser 1884.png|thumb|right|Nineteenth-century [[Engineering:Electrolytic cell|electrolytic cell]] for producing oxyhydrogen]]
'''Oxyhydrogen''' is a mixture of [[Chemistry:Hydrogen|hydrogen]] (H<sub>2</sub>) and [[Chemistry:Oxygen|oxygen]] (O<sub>2</sub>) gases. This gaseous mixture is used for torches to process [[Chemistry:Refractory|refractory]] materials and was the first<ref>
{{citation
 |author      = Howard Monroe Raymond
 |title       = Modern Shop Practice volume 1
 |chapter     = Oxy-Hydrogen Welding
 |publisher   = American Technical Society
 |year        = 1916
 |chapter-url         = http://chestofbooks.com/crafts/machinery/Shop-Practice-V1/Oxy-Hydrogen-Welding.html
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20110306125405/http://chestofbooks.com/crafts/machinery/Shop-Practice-V1/Oxy-Hydrogen-Welding.html
 |archive-date = March 6, 2011
 }}
</ref>
gaseous mixture used for [[Chemistry:Welding|welding]]. Theoretically, a ratio of 2:1 hydrogen:oxygen is enough to achieve maximum efficiency; in practice a ratio 4:1 or 5:1 is needed to avoid an oxidizing flame.<ref>
{{Cite book
 |last        = Viall
 |first       = Ethan
 |title       = Gas Torch and Thermite Welding
 |publisher   = McGraw-Hill
 |year        = 1921
 |page        = [https://archive.org/details/gastorchthermitw00vialrich/page/10 10]
 |url         = https://archive.org/details/gastorchthermitw00vialrich
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20160803205751/https://archive.org/details/gastorchthermitw00vialrich
 |archive-date = August 3, 2016
}}
</ref>

This mixture may also be referred to as '''''{{lang|de|Knallgas}}''''' (Scandinavian and German ''{{linktext|Knallgas}}''; {{literal|bang-gas}}), although some authors define knallgas to be a generic term for the mixture of fuel with the precise amount of oxygen required for complete combustion, thus 2:1 oxyhydrogen would be called "hydrogen-knallgas".<ref>W. Dittmar, "Exercises in quantitative chemical analysis", 1887, [https://archive.org/details/exercisesinquan00dittgoog/page/n207 p. 189] {{webarchive|url=https://web.archive.org/web/20140627184941/http://books.google.com/books?id=ayFDAAAAIAAJ&pg=PA189 |date=June 27, 2014 }}</ref>

"Brown's gas" and HHO are terms for oxyhydrogen originating in [[Unsolved:Pseudoscience|pseudoscience]].

== Properties ==
Oxyhydrogen will [[Physics:Combustion|combust]] when brought to its [[Chemistry:Autoignition temperature|autoignition temperature]].  For the stoichiometric mixture in air, at normal [[Physics:Atmospheric pressure|atmospheric pressure]], autoignition occurs at about 570&nbsp;°C (1065&nbsp;°F).<ref name="NASA"/>  The minimum energy required to ignite such a mixture, at lower temperatures, with a spark is about 20 [[Joule|microjoule]]s.<ref name="NASA"/>  At [[Standard conditions for temperature and pressure|standard temperature and pressure]], oxyhydrogen can burn when it is between about 4% and 95% hydrogen by volume.<ref>{{cite journal |last1=Moyle |first1=Morton |last2=Morrison |first2=Richard |last3=Churchill |first3=Stuart |title=Detonation Characteristics of Hydrogen Oxygen Mixtures |journal=AIChE Journal |date=March 1960 |volume=6 |issue=1 |pages=92–96 |doi=10.1002/aic.690060118 |bibcode=1960AIChE...6...92M |hdl=2027.42/37308 |url=https://deepblue.lib.umich.edu/bitstream/handle/2027.42/37308/690060118_ftp.pdf?sequence=1&isAllowed=y|hdl-access=free }}</ref><ref  name="NASA">
{{Cite book
 |last        = O'Connor
 |first       = Ken
 |title       = NASA Glenn Research Center Glenn Safety Manual
 |chapter     = Hydrogen
 |chapter-url  = http://www.nfpa.org/assets/files/pdf/codesstandards/hcgnasahydrogench06.pdf
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20130202184446/http://www.nfpa.org/assets/files/pdf/codesstandards/hcgnasahydrogench06.pdf
 |archive-date = February 2, 2013
}}
</ref>

When ignited, the gas mixture converts to [[Physics:Water vapor|water vapor]] and  [[Physics:Heat of combustion|releases energy]], which sustains the reaction: 241.8 [[Joule|kJ]] of energy (LHV) for every [[Mole (unit)|mole]] of {{chem2|H2}} burned.  The amount of heat energy released is independent of the mode of combustion, but the temperature of the flame varies.<ref name="encyclopedia">{{cite EB1911 |wstitle=Oxyhydrogen Flame |volume=20 |page=424}}</ref>  The maximum temperature of about {{convert|2800|°C|°F|-2}} is achieved with an exact [[Chemistry:Stoichiometry|stoichiometric]] mixture, about {{convert|700|C-change|F-change|-2}} hotter than a hydrogen flame in air.<ref>
{{Cite web
 |last        = Calvert
 |first       = James B.
 |title       = Hydrogen
 |publisher   = [[Organization:University of Denver|University of Denver]]
 |date        = April 21, 2008
 |access-date  = April 23, 2009
 |url         = http://mysite.du.edu/~jcalvert/phys/hydrogen.htm
 |quote       = An air-hydrogen torch flame reaches 2045&nbsp;°C, while an oxyhydrogen flame reaches 2660&nbsp;°C.
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20090418033147/http://mysite.du.edu/~jcalvert/phys/hydrogen.htm
 |archive-date = April 18, 2009
}}
</ref><ref>
{{Cite web
 |title       = Adiabatic Flame Temperature
 |work        = The Engineering Toolbox
 |access-date  = April 23, 2009
 |url         = http://www.engineeringtoolbox.com/adiabatic-flame-temperature-d_996.html
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20080128053804/http://www.engineeringtoolbox.com/adiabatic-flame-temperature-d_996.html
 |archive-date = January 28, 2008
}}
"Oxygen as Oxidizer: 3473&nbsp;K, Air as Oxidizer: 2483&nbsp;K"
</ref><ref>
{{Cite web
 |title       = Temperature of a Blue Flame
 |access-date  = April 5, 2008
 |url         = http://hypertextbook.com/facts/1998/JamesDanyluk.shtml
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20080316074504/http://hypertextbook.com/facts/1998/JamesDanyluk.shtml
 |archive-date = March 16, 2008
}}
"Hydrogen in air: 2,400&nbsp;K, Hydrogen in Oxygen: 3,080 K"
</ref>
When either of the gases are mixed in excess of this ratio, or when mixed with an [[Physics:Inert gas|inert gas]] like nitrogen, the heat must spread throughout a greater quantity of matter and the flame temperature will be lower.<ref name="encyclopedia"/>

== Production by electrolysis ==
A pure stoichiometric mixture may be obtained by [[Physics:Electrolysis of water|water electrolysis]], which uses an [[Physics:Electric current|electric current]] to dissociate the water molecules:
: Electrolysis: {{chem2|2 H2O -> 2 H2 + O2}}
: Combustion: {{chem2|2 H2 + O2 -> 2 H2O}}
[[Biography:William Nicholson (chemist)|William Nicholson]] was the first to decompose water in this manner in 1800. In theory, the input energy of a closed system always equals the output energy, as the [[Physics:First law of thermodynamics|first law of thermodynamics]] states. However, in practice no systems are perfectly closed, and the energy required to generate the oxyhydrogen always exceeds the energy released by combusting it, even at maximum practical efficiency, as the [[Physics:Second law of thermodynamics|second law of thermodynamics]] implies (see [[Physics:Electrolysis of water#Efficiency|Electrolysis of water]]).

== Applications ==
[[Image:Limelight diagram.svg|thumb|[[Physics:Limelight|Limelight]]s used an oxyhydrogen flame as a high-temperature heat source]]

=== Lighting ===
Many forms of oxyhydrogen [[Physics:Gas lighting|lamp]]s have been described, such as the [[Physics:Limelight|limelight]], which used an oxyhydrogen flame to heat a piece of [[Chemistry:Calcium oxide|lime]] to [[Astronomy:Black body|white hot]] [[Physics:Incandescence|incandescence]].<ref name="WT"/>  Because of the explosiveness of the oxyhydrogen, limelights have been replaced by electric lighting.

===Oxyhydrogen blowpipe===
[[Image:Blowpipe - circa 1827.jpg|thumb|Nineteenth-century bellows-operated oxy-hydrogen blowpipe, including two different types of [[Physics:Flashback arrestor|flashback arrestor]]]] The foundations of the oxy-hydrogen blowpipe were laid down by Carl Wilhelm Scheele and Joseph Priestley around the last quarter of the eighteenth century. The oxy-hydrogen blowpipe itself was developed by the {{wipe|France}} Bochard-de-Saron, the {{wipe|England}} mineralogist Edward Daniel Clarke and the {{wipe|United States}} [[Chemist|chemist]] Robert Hare in the late 18th and early 19th centuries.<ref>{{Cite journal| publisher = Manufacturing chemists| title = Report on the Development of the Chemical Arts During the Last Ten Years| journal=Chemical News |date = 1875|last=Hofmann |first=A. W. |url=https://books.google.com/books?id=v2sfCwFk28AC&pg=RA1-PA153}}</ref> It produced a flame hot enough to melt such refractory materials as platinum, porcelain, fire brick, and corundum, and was a valuable tool in several fields of science.<ref>{{cite book | last = Griffin | first = John Joseph | title = A Practical Treatise on the Use of the Blowpipe in Chemical and Mineral Analysis | publisher = R. Griffin & co.| year = 1827 | location = Glasgow | url = https://archive.org/details/apracticaltreat00grifgoog }}</ref> It is used in the [[Earth:Verneuil process|Verneuil process]] to produce synthetic corundum.<ref>{{cite encyclopedia|encyclopedia= Encyclopaedia Britannica|title= Verneuil process |url= https://www.britannica.com/topic/Verneuil-process|access-date=July 11, 2018 |language= en|date= October 22, 2013}}
</ref>

===Oxyhydrogen torch===
An ''oxyhydrogen torch'' (also known as ''hydrogen torch'') is an [[Physics:Oxy-fuel welding and cutting#Hydrogen|oxy-gas torch]] that burns hydrogen (the fuel) with oxygen (the oxidizer). It is used for cutting and [[Chemistry:Welding|welding]]<ref>{{citation |chapter= 24.4 Oxyhydrogen welding |title= Manufacturing technology: foundry, forming and welding |author= P. N. Rao |edition= 2 |publisher= Tata McGraw-Hill Education |year= 2001 |isbn= 978-0-07-463180-5 |pages= 373–374 |chapter-url= https://books.google.com/books?id=I4RZQaxCRP8C&q=oxyhydrogen+welding&pg=PA373 |url-status= live |archive-url= https://web.archive.org/web/20140627193730/http://books.google.com/books?id=I4RZQaxCRP8C&pg=PA373&dq=oxyhydrogen+welding&hl=en&ei=RP5eTdDhGtLB4gb0k7GVCg&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDYQ6AEwAg |archive-date= June 27, 2014 }}</ref> [[Chemistry:Metal|metal]]s, [[Chemistry:Glass|glass]]es, and [[Chemistry:Thermoplastic|thermoplastic]]s.<ref name="WT">{{cite book |title=Chemical Discovery and Invention in the Twentieth Century |first=William Augustus |last=Tilden |publisher=Adamant Media Corporation |isbn=978-0-543-91646-4|url=https://books.google.com/books?id=Qu-fYeT8UKoC&q=Oxyhydrogen&pg=PP133 |page=80 |year=1926}}</ref>

Due to competition from arc welding and other [[Physics:Oxy-fuel welding and cutting|oxy-fuel torches]] such as the acetylene-fueled cutting torch, the oxyhydrogen torch is seldom used today, but it remains the preferred cutting tool in some niche applications.

Oxyhydrogen was once used in working [[Chemistry:Platinum|platinum]], because at the time, only it could burn hot enough to melt the metal {{convert|1768.3|°C|°F}}.<ref name="encyclopedia"/> These techniques have been superseded by the [[Physics:Electric arc furnace|electric arc furnace]].

== Pseudoscientific claims ==
{{anchor|HHO gas}} {{anchor|Brown's gas}}
Oxyhydrogen is associated with various exaggerated claims.<ref>{{Cite web|url=http://www.eagle-research.com/browngas/myth/myth.php|title=Eagle Research Institute - Brown's Gas - Myth-conceptions|archive-url=https://web.archive.org/web/20190418000551/http://www.eagle-research.com/browngas/myth/myth.php|access-date=July 11, 2018|archive-date=April 18, 2019}}</ref><ref name="Ball2007">{{cite journal | last=Ball | first=Philip | title=Burning water and other myths | journal=News@nature | publisher=Springer Nature | date=September 10, 2007 | issn=1744-7933 | doi=10.1038/news070910-13 | s2cid=129704116 | doi-access=free }}</ref><ref name="Ball2006">{{cite journal|last=Ball|first=Philip|year=2006|title=Nuclear waste gets star attention|journal=News@nature|issn=1744-7933|doi=10.1038/news060731-13|s2cid=121246705}}</ref> It is often called "Brown's gas" or "HHO gas", a term popularized by fringe physicist<ref>{{cite news|last=Weimar|first=Carrie|title=Snubbed By Mainstream, Scientist Sues|url=https://news.google.com/newspapers?id=BYtIAAAAIBAJ&pg=1570,2000590&dq=ruggero-santilli+fringe&hl=en|access-date=February 3, 2011|newspaper=St. Petersburg Times|date=May 7, 2007}}</ref> [[Biography:Ruggero Santilli#HHO gas|Ruggero Santilli]], who claimed that his HHO gas, produced by a special apparatus, is "a new form of water", with new properties, based on his [[Philosophy:Fringe theory|fringe theory]] of "magnecules".<ref name="Ball2006"/>

Many other pseudoscientific claims have been made about oxyhydrogen, like an ability to neutralize radioactive waste, help plants to germinate, and more.<ref name="Ball2006"/>

Oxyhydrogen is often mentioned in conjunction with [[Unsolved:Water-fuelled car|vehicles that claim to use water as a fuel]]. The most common and decisive counter-argument against producing this gas on board to use as a fuel or fuel additive is that more energy is always needed to split water molecules than is recouped by burning the resulting gas.<ref name="Ball2007"/><ref name="Schadewald 2008 p. ">{{cite book | last=Schadewald | first=R.J. | title=Worlds of Their Own: A Brief History of Misguided Ideas: Creationism, Flat-Earthism, Energy Scams, and the Velikovsky Affair | publisher=Xlibris US | year=2008 | isbn=978-1-4628-1003-1 | url=https://books.google.com/books?id=m9BM6DzFGGwC | access-date=July 11, 2018 }}</ref> Additionally, the volume of gas that can be produced for on-demand consumption through electrolysis is very small in comparison to the volume consumed by an internal combustion engine.<ref>{{cite news|last=Simpson|first=Bruce|title=The proof that HHO is a scam|url=http://www.aardvark.co.nz/hho_scam.shtml|access-date=February 12, 2012|newspaper=Aardvark Daily|date=May 2008|url-status=live|archive-url=https://web.archive.org/web/20120211215854/http://www.aardvark.co.nz/hho_scam.shtml|archive-date=February 11, 2012}}</ref>

An article in ''Popular Mechanics'' in 2008 reported that oxyhydrogen does not increase the fuel economy in automobiles.<ref>[http://www.popularmechanics.com/cars/a3499/4276846/ Water-Powered Cars: Hydrogen Electrolyzer Mod Can't Up MPGs] {{webarchive|url=https://web.archive.org/web/20150320180153/http://www.popularmechanics.com/cars/a3499/4276846/ |date=March 20, 2015 }}, Mike Allen, August 7, 2008, Popularmechanics.com</ref>

"Water-fueled" cars should not be confused with hydrogen-fueled cars, where the hydrogen is produced elsewhere and used as fuel or where it is used [[Physics:Hydrogen fuel enhancement|as fuel enhancement]].

== References ==
{{Reflist|30em}}


[[Category:Chemical mixtures]]
[[Category:Electrolysis]]
[[Category:Oxygen]]
[[Category:Hydrogen technologies]]
[[Category:Hydrogen production]]
[[Category:Industrial gases]]

{{Sourceattribution|Oxyhydrogen}}