Editing Chemical reaction (section)

==Applications==
[[File:Velp-thermitewelding-1.jpg|thumb|Thermite reaction proceeding in railway welding. Shortly after this, the liquid iron flows into the mould around the rail gap.]]
Chemical reactions are central to [[chemical engineering]], where they are used for the synthesis of new compounds from natural raw materials such as [[petroleum]], mineral [[ore]]s, and [[oxygen]] in air. It is essential to make the reaction as efficient as possible, maximizing the yield and minimizing the number of reagents, energy inputs and waste. [[Catalyst]]s are especially helpful for reducing the energy required for the reaction and increasing its [[reaction rate]].<ref>{{cite book | author = Emig, Gerhard | author2 =  Klemm, Elias | title = Technical Chemistry | edition = 5th | language = de | publisher = [[Springer Science+Business Media|Springer]] | year = 2005 | isbn = 978-3-540-23452-4 | pages = 33–34}}</ref><ref>{{Cite journal | doi = 10.1126/science.1962206| title = The atom economy – a search for synthetic efficiency| journal = Science| volume = 254| issue = 5037| pages = 1471–1477| year = 1991| last1 = Trost | first1 = B. | pmid=1962206| bibcode = 1991Sci...254.1471T}}</ref>

Some specific reactions have their niche applications. For example, the [[thermite]] reaction is used to generate light and heat in [[pyrotechnics]] and [[welding]]. Although it is less controllable than the more conventional [[Oxy-fuel welding and cutting|oxy-fuel welding]], [[arc welding]] and [[flash welding]], it requires much less equipment and is still used to mend rails, especially in remote areas.<ref>{{cite encyclopedia | editor = John J. McKetta | author = Weismantel, Guy E | year = 1999 | url = https://books.google.com/books?id=MfjDlUe8Kc0C&pg=PA109 | title= Encyclopedia of Chemical Processing and Design | volume = 67 | publisher = [[CRC Press]] | page = 109 | isbn = 978-0-8247-2618-8}}</ref>