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Acidity of Frozen Electrolyte Solutions

Robinson, Carmen and Boxe, C. S. and Guzmán, M. I. and Colussi, A. J. and Hoffmann, M. R. (2006) Acidity of Frozen Electrolyte Solutions. Journal of Physical Chemistry B, 110 (15). pp. 7613-7616. ISSN 1520-6106. doi:10.1021/jp061169n.

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Ice is selectively intolerant to impurities. A preponderance of implanted anions or cations generates electrical imbalances in ice grown from electrolyte solutions. Since the excess charges are ultimately neutralized via interfacial (H^+/HO^-) transport, the acidity of the unfrozen portion can change significantly and permanently. This insufficiently recognized phenomenon should critically affect rates and equilibria in frozen media. Here we report the effective 19F NMR chemical shift of 3-fluorobenzoic acid as in situ probe of the acidity of extensively frozen electrolyte solutions. The sign and magnitude of the acidity changes associated with freezing are largely determined by specific ion combinations, but depend also on solute concentration and/or the extent of supercooling. NaCl solutions become more basic, those of (NH_4)_2SO_4 or Na_2SO_4 become more acidic, while solutions of the 2-(N-morpholino)ethanesulfonic acid zwitterion barely change their acidity upon freezing. We discuss how acidity scales based on solid-state NMR measurements could be used to assess the degree of ionization of weak acids and bases in frozen media.

Item Type:Article
Related URLs:
URLURL TypeDescription
Guzmán, M. I.0000-0002-6730-7766
Colussi, A. J.0000-0002-3400-4101
Hoffmann, M. R.0000-0001-6495-1946
Additional Information:© 2006 American Chemical Society. Received: February 23, 2006; In Final Form: March 13, 2006. C.R. was a MURF student. C.S.B. acknowledges support from the Betty and Gordon Moore Foundation. This work was financed by NSF grants ATM-0228140 and ATM-0534990.
Funding AgencyGrant Number
Caltech Minorities Undergraduate Research Fellowship (MURF)UNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Issue or Number:15
Record Number:CaltechAUTHORS:20150623-154753551
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Official Citation:Acidity of Frozen Electrolyte Solutions Carmen Robinson, C. S. Boxe, M. I. Guzmán, A. J. Colussi, and M. R. Hoffmann The Journal of Physical Chemistry B 2006 110 (15), 7613-7616 DOI: 10.1021/jp061169n
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58470
Deposited By: George Porter
Deposited On:28 Jul 2015 22:22
Last Modified:10 Nov 2021 22:05

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