Old Nassau reaction
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The Old Nassau reaction or Halloween reaction is a chemical clock reaction in which a clear solution turns orange and then black. This reaction was discovered by two undergraduate students at Princeton University researching the inhibition of the iodine clock reaction (or Landolt reaction) by Hg2+, resulting in the formation of orange HgI2. Orange and black are the school colors of Princeton University, and "Old Nassau" is a nickname for Princeton, named for its historic administration building, Nassau Hall.
Chemical equation
The reactions involved are as follows:
- Na2S2O5 + H2O → 2 NaHSO3
- IO3− + 3 HSO3− → I− + 3 SO42− + 3 H+
This reaction reduces iodate ions to iodide ions. - Hg2+ + 2 I− → HgI2
Orange mercury iodide solid is precipitated until the mercury is used up. - IO3− + 5 I− + 6 H+ → 3 I2 + 3 H2O
The excess I− and IO3− undergo the iodide-iodate reaction - I2 + starch → a blue/black complex
A blue/black starch-iodine complex is formed.
See also
References
- {{cite journal | last1 = Alyea | first1 = Hubert N. | title = The Old Nassau reaction | journal = Journal of Chemical Education | volume = 54 | pages = 167 | year = 1977 | doi = 10.1021/ed054p167.2|bibcode = 1977JChEd..54..167A }}
- {{cite web | url = http://www.dcb-server.unibe.ch/dcbneu/studies/pharmazie/PCI/OldNassau07.pdf | title = Simulation und praktische Durchführung der „Old Nassau” Uhr-Reaktion | url-status = dead | archiveurl = https://web.archive.org/web/20110707004220/http://www.dcb-server.unibe.ch/dcbneu/studies/pharmazie/PCI/OldNassau07.pdf | archivedate = 2011-07-07 }}
- {{cite journal | last1 = Lambert | first1 = Jack L. | last2 = Fina | first2 = Gary T. | title = Iodine clock reaction mechanisms | journal = Journal of Chemical Education | volume = 61 | pages = 1037 | year = 1984 | doi = 10.1021/ed061p1037|bibcode = 1984JChEd..61.1037L }}
- {{cite web | url = https://www.mun.ca/educ/ed4361/virtual_academy/campus_a/woodlandm/Demo1.html | title = Old Nassau - Halloween Reaction }}
- {{cite journal | last1 = Huber | first1 = Hanspeter | title = Simulation of the Old Nassau Reaction | journal = Journal of Chemical Education | volume = 56 | pages = 320 | year = 1979 | doi = 10.1021/ed056p320|bibcode = 1979JChEd..56..320H }}
- {{cite journal | last1 = Fortman | first1 = John J. | title = The old Nassau demonstration: Educational and entertaining variations | journal = Journal of Chemical Education | volume = 69 | pages = 236 | year = 1992 | doi = 10.1021/ed069p236|bibcode = 1992JChEd..69..236F }}
- {{cite web | url =http://www.chemie.uni-regensburg.de/Organische_Chemie/Didaktik/Keusch/D-Old_Nassau-d.htm| title = Cocktail 'Old Nassau' - Modifizierte Landolt Reaktion| author = Peter Keusch}}
- {{cite journal | last1 = Moss | first1 = Arthur | title = The Landolt, "Old Nassau", and variant reactions | journal = Journal of Chemical Education | volume = 55 | pages = 244 | year = 1978 | doi = 10.1021/ed055p244.2|bibcode = 1978JChEd..55Q.244M }}
- {{cite journal | last1 = Wilkinson | first1 = Lawrence E. | last2 = David Speckhard | last3 = James H. Maynard | title = Old Nassau Demonstration with Wilkinson Modification | journal = Journal of Chemical Education | volume = 81 | pages = 1474 | year = 2004 | doi = 10.1021/ed081p1474|bibcode = 2004JChEd..81.1474W }}
- {{cite journal | last1 = Moss | first1 = Arthur | title = The Landolt, "Old Nassau", and variant reactions | journal = Journal of Chemical Education | volume = 55 | pages = 244 | year = 1978 | doi = 10.1021/ed055p244.2|bibcode = 1978JChEd..55Q.244M }}
- {{cite journal | last1 = Lambert | first1 = Jack L. | last2 = Fina | first2 = Gary T. | title = Iodine clock reaction mechanisms | journal = Journal of Chemical Education | volume = 61 | pages = 1037 | year = 1984 | doi = 10.1021/ed061p1037|bibcode = 1984JChEd..61.1037L }}
- {{cite journal | last1 = Autuori | first1 = Marcos Alberto | last2 = Brolo | first2 = Alexandre Guimaraes | last3 = Mateus | first3 = Alfredo Luis M. L. | title = The iodine clock reaction: A surprising variant | journal = Journal of Chemical Education | volume = 66 | pages = 852 | year = 1989 | doi = 10.1021/ed066p852.1|bibcode = 1989JChEd..66..852A }}