“…Good agreement with Fogo's results is obtained, particularly in the intermediate density region, as shown more precisely in Figure , where deviations of several sets of experimental p K m results from eq 13 are plotted in as a function of water density. The agreement with Fogo et al and Pearson et al. results is remarkable considering that these results were obtained over 40 years ago.…”
Section: Discussionsupporting
confidence: 89%
“…Symbol assignments are the same as in Figure . The results of Fogo et al were recalculated using the FHFP equation. The x axis is linear with respect to 1/ T . 6 Deviations of experimental results for NaCl(aq) from eq 13, [p K m (expt) − p K m (calc)], as a function of water density.…”
Section: Discussionmentioning
confidence: 99%
“…Symbol assignments are the same as in Figure . The results of Fogo et al were recalculated using the FHFP equation. The x axis is linear with respect to 1/ T .…”
Section: Discussionmentioning
confidence: 99%
“…It should be expected that extrapolation toward the critical point of simple empirical correlations of the ion pair dissociation constants and limiting conductances as functions of temperature and density, determined from measurements far from the critical point of water, will fail as the critical point is approached. Indeed, the results of Fogo et al showed a significant change of slope in the temperature dependence of K m occurring already relatively far from the critical region. One of the goals of this work was to explore K m and Λ 0 near the critical point.…”
Section: Introductionmentioning
confidence: 95%
“…The isobars are 10 MPa and 15, 16, ..., 28 MPa. The symbols represent the measurements of, (□) Fogo et al ; (◇) Pearson et al. ; (☆) Ho et al.…”
Conductivities of LiCl(aq), NaCl(aq), NaBr(aq), and
CsBr(aq) solutions have been measured in the range of
concentrations from 0.013 to 4 × 10-8
mol·dm-3 using a flow conductance cell
at temperatures between 603
K and 674 K and pressures between 15 MPa and 28 MPa (water densities
from 650 to 200 kg·m-3).
Limiting
equivalent conductances and ionization equilibrium constants calculated
from the concentration dependence
of the equivalent conductance are reported. Previous measurements
of equilibrium constants in the low-density supercritical region, although of lesser accuracy, agree well
with the present results. Even at the
critical density and 2.5 K above the critical temperature there is no
evidence for the critical effects which
make the Debye−Hückel limiting law invalid at the critical
isotherm−isobar. No critical scaling of Λ0
is
observed. Walden's rule is not obeyed and the Stokes radius
increases by 70% near the critical region as the
density goes from 700 to 200 kg·m-3,
suggesting an increase in the number of water molecules carried
along
with the ion. The differences in mobility between different ions
are rather small when compared to the
differences in crystallographic ionic radii. The association
constants are in the order CsBr < NaBr < NaCl
≈ LiCl.
“…Good agreement with Fogo's results is obtained, particularly in the intermediate density region, as shown more precisely in Figure , where deviations of several sets of experimental p K m results from eq 13 are plotted in as a function of water density. The agreement with Fogo et al and Pearson et al. results is remarkable considering that these results were obtained over 40 years ago.…”
Section: Discussionsupporting
confidence: 89%
“…Symbol assignments are the same as in Figure . The results of Fogo et al were recalculated using the FHFP equation. The x axis is linear with respect to 1/ T . 6 Deviations of experimental results for NaCl(aq) from eq 13, [p K m (expt) − p K m (calc)], as a function of water density.…”
Section: Discussionmentioning
confidence: 99%
“…Symbol assignments are the same as in Figure . The results of Fogo et al were recalculated using the FHFP equation. The x axis is linear with respect to 1/ T .…”
Section: Discussionmentioning
confidence: 99%
“…It should be expected that extrapolation toward the critical point of simple empirical correlations of the ion pair dissociation constants and limiting conductances as functions of temperature and density, determined from measurements far from the critical point of water, will fail as the critical point is approached. Indeed, the results of Fogo et al showed a significant change of slope in the temperature dependence of K m occurring already relatively far from the critical region. One of the goals of this work was to explore K m and Λ 0 near the critical point.…”
Section: Introductionmentioning
confidence: 95%
“…The isobars are 10 MPa and 15, 16, ..., 28 MPa. The symbols represent the measurements of, (□) Fogo et al ; (◇) Pearson et al. ; (☆) Ho et al.…”
Conductivities of LiCl(aq), NaCl(aq), NaBr(aq), and
CsBr(aq) solutions have been measured in the range of
concentrations from 0.013 to 4 × 10-8
mol·dm-3 using a flow conductance cell
at temperatures between 603
K and 674 K and pressures between 15 MPa and 28 MPa (water densities
from 650 to 200 kg·m-3).
Limiting
equivalent conductances and ionization equilibrium constants calculated
from the concentration dependence
of the equivalent conductance are reported. Previous measurements
of equilibrium constants in the low-density supercritical region, although of lesser accuracy, agree well
with the present results. Even at the
critical density and 2.5 K above the critical temperature there is no
evidence for the critical effects which
make the Debye−Hückel limiting law invalid at the critical
isotherm−isobar. No critical scaling of Λ0
is
observed. Walden's rule is not obeyed and the Stokes radius
increases by 70% near the critical region as the
density goes from 700 to 200 kg·m-3,
suggesting an increase in the number of water molecules carried
along
with the ion. The differences in mobility between different ions
are rather small when compared to the
differences in crystallographic ionic radii. The association
constants are in the order CsBr < NaBr < NaCl
≈ LiCl.
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