A nuclear magnetic resonance study : the kinetics of hydrogen exchange reactions in aqueous 15NH+4 solution

Thompson, Linda B. (1976) A nuclear magnetic resonance study : the kinetics of hydrogen exchange reactions in aqueous 15NH+4 solution. Masters thesis, Memorial University of Newfoundland.

[img] [English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version
Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.

Download (10Mb)
  • [img] [English] PDF - Accepted Version
    Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
    (Original Version)

Abstract

A study of the proton exchange reactions of ¹⁵NH⁺₄ that take place in aqueous acidic solution was conducted. Nuclear magnetic resonance methods were used to measure NH and OH line broadening resulting from exchange over the temperature range 30゚C to 80゚C, enabling computation of activation parameters for the reactions: -- reaction (4): [special characters omitted] -- reaction (6): [special characters omitted], and -- reaction (7): [special characters omitted] -- Activation energies of essentially zero for reactions (-4) and (7) have been reported in a previous study of aqueous acidic ¹⁴NH⁺₄ proton exchange reactions. Since, for the recombination reaction, any mechanism which might be associated with an activation energy of zero is inconsistant with the diffusion mechanism indicated by the bulk of data on such reactions, this study was undertaken. The ¹⁵N isotope was used to eliminate the possibility of a contribution to the NH linewidth by broadening due to quadrupolar relaxation. -- The activation enthalpy for reaction (4) was found to be 14.6 kcal mole⁻¹. Rate constants for reaction (-4) were found to conform well to a model for diffusion controlled reactions with ∆H*₋₄ equal to 2.2 ± 0.3 kcal mole⁻¹, and with Po a constant equal to (4.2 ± 0.2) x 10⁻⁸ cm. ∆H*₇ was also found to have a non zero value, 4.3 ± 1.6 kcal mole⁻¹; and ∆H*₆ was found to equal 5.6 ± 1.3 kcal mole⁻¹.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/7553
Item ID: 7553
Additional Information: Bibliography: leaves 87-89.
Department(s): Science, Faculty of > Chemistry
Date: 1976
Date Type: Submission
Library of Congress Subject Heading: Ammonium ions; Exchange reactions

Actions (login required)

View Item View Item

Downloads

Downloads per month over the past year

View more statistics