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Title: Thermodynamic properties of the ionization of morpholine as a function of temperature and ionic strength

Abstract

Morpholine, O(C{sub 2}H{sub 4}){sub 2}(NH), is widely used in many industrial applications as a pH buffering agent and corrosion inhibitor; in particular, it is utilized at elevated temperatures in nuclear power plants. A hydrogen-electrode concentration cell was used to monitor pH in a study of morpholine ionization in aqueous solutions to temperatures of 290 C and to ionic strengths of 1 m, maintained with either sodium trifluoromethanesulfonate or sodium chloride. The resulting hydrolysis quotients were combined with values from two previous potentiometric investigations of this reaction, as well as existing heat capacity and apparent molar volume data, to provide a global fitting equation. The computed thermodynamic parameters for the acid dissociation of the morpholinium ion at 25 C and infinite dilution are log K = ({minus}8.491 {+-} 0.003); {Delta}H = (39 {+-} 1) kJ/mol; {Delta}S = ({minus}31 {+-} 1) J/K{center_dot}mol; {Delta}C{sub p} = (40 {+-} 7) J/K{center_dot}mol; and {Delta}V = (3 {+-} 1) cm{sup 3}/mol. At low ionic strengths, including values at infinite dilution, the log Q data were found to be near linear with respect to the reciprocal temperature in Kelvin over the measured temperature range of 0 C to 300 C.

Authors:
; ; ;
Publication Date:
Research Org.:
Texas Tech Univ., Lubbock, TX (US)
Sponsoring Org.:
USDOE; Electric Power Research Institute
OSTI Identifier:
20076020
Resource Type:
Journal Article
Journal Name:
Journal of Chemical and Engineering Data
Additional Journal Information:
Journal Volume: 45; Journal Issue: 3; Other Information: PBD: May-Jun 2000; Journal ID: ISSN 0021-9568
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; MORPHOLINES; CORROSION INHIBITORS; NUCLEAR POWER PLANTS; THERMODYNAMIC PROPERTIES; IONIZATION; IONIC CONDUCTIVITY; PH VALUE; WATER CHEMISTRY

Citation Formats

Ridley, M.K., Xiao, C., Palmer, D.A., and Wesolowski, D.J. Thermodynamic properties of the ionization of morpholine as a function of temperature and ionic strength. United States: N. p., 2000. Web. doi:10.1021/je9903146.
Ridley, M.K., Xiao, C., Palmer, D.A., & Wesolowski, D.J. Thermodynamic properties of the ionization of morpholine as a function of temperature and ionic strength. United States. doi:10.1021/je9903146.
Ridley, M.K., Xiao, C., Palmer, D.A., and Wesolowski, D.J. Thu . "Thermodynamic properties of the ionization of morpholine as a function of temperature and ionic strength". United States. doi:10.1021/je9903146.
@article{osti_20076020,
title = {Thermodynamic properties of the ionization of morpholine as a function of temperature and ionic strength},
author = {Ridley, M.K. and Xiao, C. and Palmer, D.A. and Wesolowski, D.J.},
abstractNote = {Morpholine, O(C{sub 2}H{sub 4}){sub 2}(NH), is widely used in many industrial applications as a pH buffering agent and corrosion inhibitor; in particular, it is utilized at elevated temperatures in nuclear power plants. A hydrogen-electrode concentration cell was used to monitor pH in a study of morpholine ionization in aqueous solutions to temperatures of 290 C and to ionic strengths of 1 m, maintained with either sodium trifluoromethanesulfonate or sodium chloride. The resulting hydrolysis quotients were combined with values from two previous potentiometric investigations of this reaction, as well as existing heat capacity and apparent molar volume data, to provide a global fitting equation. The computed thermodynamic parameters for the acid dissociation of the morpholinium ion at 25 C and infinite dilution are log K = ({minus}8.491 {+-} 0.003); {Delta}H = (39 {+-} 1) kJ/mol; {Delta}S = ({minus}31 {+-} 1) J/K{center_dot}mol; {Delta}C{sub p} = (40 {+-} 7) J/K{center_dot}mol; and {Delta}V = (3 {+-} 1) cm{sup 3}/mol. At low ionic strengths, including values at infinite dilution, the log Q data were found to be near linear with respect to the reciprocal temperature in Kelvin over the measured temperature range of 0 C to 300 C.},
doi = {10.1021/je9903146},
journal = {Journal of Chemical and Engineering Data},
issn = {0021-9568},
number = 3,
volume = 45,
place = {United States},
year = {2000},
month = {6}
}