Water surface is acidic
Water autoionization reaction 2H2O → H3O− + OH− is a textbook process of basic importance, resulting in pH = 7 for pure water. However, pH of pure water surface is shown to be significantly lower, the reduction being caused by proton stabilization at the surface. The evidence presented here includes...
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ftpubmed:oai:pubmedcentral.nih.gov:1863452 2023-05-15T15:52:38+02:00 Water surface is acidic Buch, Victoria Milet, Anne Vácha, Robert Jungwirth, Pavel Devlin, J. Paul 2007-05-01 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1863452 http://www.ncbi.nlm.nih.gov/pubmed/17452650 https://doi.org/10.1073/pnas.0611285104 en eng National Academy of Sciences http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1863452 http://www.ncbi.nlm.nih.gov/pubmed/17452650 http://dx.doi.org/10.1073/pnas.0611285104 © 2007 by The National Academy of Sciences of the USA Physical Sciences Text 2007 ftpubmed https://doi.org/10.1073/pnas.0611285104 2013-08-31T20:41:04Z Water autoionization reaction 2H2O → H3O− + OH− is a textbook process of basic importance, resulting in pH = 7 for pure water. However, pH of pure water surface is shown to be significantly lower, the reduction being caused by proton stabilization at the surface. The evidence presented here includes ab initio and classical molecular dynamics simulations of water slabs with solvated H3O+ and OH− ions, density functional studies of (H2O)48H+ clusters, and spectroscopic isotopic-exchange data for D2O substitutional impurities at the surface and in the interior of ice nanocrystals. Because H3O+ does, but OH− does not, display preference for surface sites, the H2O surface is predicted to be acidic with pH < 4.8. For similar reasons, the strength of some weak acids, such as carbonic acid, is expected to increase at the surface. Enhanced surface acidity can have a significant impact on aqueous surface chemistry, e.g., in the atmosphere. Text Carbonic acid PubMed Central (PMC) Proceedings of the National Academy of Sciences 104 18 7342 7347 |
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English |
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Physical Sciences |
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Physical Sciences Buch, Victoria Milet, Anne Vácha, Robert Jungwirth, Pavel Devlin, J. Paul Water surface is acidic |
topic_facet |
Physical Sciences |
description |
Water autoionization reaction 2H2O → H3O− + OH− is a textbook process of basic importance, resulting in pH = 7 for pure water. However, pH of pure water surface is shown to be significantly lower, the reduction being caused by proton stabilization at the surface. The evidence presented here includes ab initio and classical molecular dynamics simulations of water slabs with solvated H3O+ and OH− ions, density functional studies of (H2O)48H+ clusters, and spectroscopic isotopic-exchange data for D2O substitutional impurities at the surface and in the interior of ice nanocrystals. Because H3O+ does, but OH− does not, display preference for surface sites, the H2O surface is predicted to be acidic with pH < 4.8. For similar reasons, the strength of some weak acids, such as carbonic acid, is expected to increase at the surface. Enhanced surface acidity can have a significant impact on aqueous surface chemistry, e.g., in the atmosphere. |
format |
Text |
author |
Buch, Victoria Milet, Anne Vácha, Robert Jungwirth, Pavel Devlin, J. Paul |
author_facet |
Buch, Victoria Milet, Anne Vácha, Robert Jungwirth, Pavel Devlin, J. Paul |
author_sort |
Buch, Victoria |
title |
Water surface is acidic |
title_short |
Water surface is acidic |
title_full |
Water surface is acidic |
title_fullStr |
Water surface is acidic |
title_full_unstemmed |
Water surface is acidic |
title_sort |
water surface is acidic |
publisher |
National Academy of Sciences |
publishDate |
2007 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1863452 http://www.ncbi.nlm.nih.gov/pubmed/17452650 https://doi.org/10.1073/pnas.0611285104 |
genre |
Carbonic acid |
genre_facet |
Carbonic acid |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1863452 http://www.ncbi.nlm.nih.gov/pubmed/17452650 http://dx.doi.org/10.1073/pnas.0611285104 |
op_rights |
© 2007 by The National Academy of Sciences of the USA |
op_doi |
https://doi.org/10.1073/pnas.0611285104 |
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Proceedings of the National Academy of Sciences |
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104 |
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18 |
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7342 |
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7347 |
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1766387759210037248 |