{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/39729"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/39729","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Phase equilibria and volumetric properties for the system NaCl-CaCl₂-H₂O","abstract":"Low temperature phase relations in the ice-stable field of the system NaCl-CaCl₂-H₂O were determined under 1 atm. total pressure along the NaCl-H₂O and CaCl₂-H₂O binaries and along five pseudobinaries with constant NaCl/(NaCl+CaCl₂) weight ratios. The results are in excellent agreement with published data along the NaCl-H₂O binary but show large discrepancies when compared to previous determinations of the ice liquidus along the CaCl₂-H₂O binary and in the NaCl-CaCl₂-H₂O ternary. At moderate to high salinities, isotherms cross the ice sub-field at lower total salt concentrations than previously reported. In addition, NaCl/(NaCl+CaCl₂) weight ratios estimated from hydrohalite- and ice-melting temperatures may be low by as much as 15%. Relative densities were measured for NaCl(aq) and CaCl₂(aq) solutions to 250°C and 400 bars and over the range of ionic strengths 0.2 - 5.5 and 0.2 - 19.2 mol·kg⁻¹, respectively. The results span the pressure and temperature of earlier volumetric studies and extend to higher molalities than reported previously. The relative densities have been fitted as apparent molar volumes (V<sub>Φ</sub>) using the Pitzer ion-interaction treatment, with appropriate expressions chosen for the temperature- and pressure-dependence of the virial coefficients of the model. The results presented for NaCl(aq) are in good agreement with published results to 250°C. The results presented for CaCl₂(aq) are in good agreement with published values to approximately 125°C. Above 125°C the inter- and intralaboratory precision of the published data deteriorate and are often in very poor agreement with the data from this Study. The representation for V<sub>Φ</sub> for CaCl₂(aq) was integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. CaCl₂ activity coefficients (γ±) have been derived to 250°C, 400 bars and 4 mol·kg⁻¹ using published fits of CaCl₂ activity coefficient data along the vapor saturation surface and the pressure dependence determined in this work. The volumetric data indicate that the mean ionic activity coefficient, γ±(CaCl₂), increases by a maximum of 32% at 400 bars, 250°C, and 4 mol·kg⁻¹ as compared with its value at saturation pressure. Relative densities were also measured for several ternary { NaCl+CaCl₂}(aq) solutions at 25 and 35°C and 1 atm. These results substantially expand the volumetric data base for ternary solutions. Based on the results of this study most of the previously reported 308.15 K density data in the ternary appear to contain large errors.","abstract_html":"Low temperature phase relations in the ice-stable field of the system NaCl-CaCl₂-H₂O were determined under 1 atm. total pressure along the NaCl-H₂O and CaCl₂-H₂O binaries and along five pseudobinaries with constant NaCl/(NaCl+CaCl₂) weight ratios. The results are in excellent agreement with published data along the NaCl-H₂O binary but show large discrepancies when compared to previous determinations of the ice liquidus along the CaCl₂-H₂O binary and in the NaCl-CaCl₂-H₂O ternary. At moderate to high salinities, isotherms cross the ice sub-field at lower total salt concentrations than previously reported. In addition, NaCl/(NaCl+CaCl₂) weight ratios estimated from hydrohalite- and ice-melting temperatures may be low by as much as 15%. Relative densities were measured for NaCl(aq) and CaCl₂(aq) solutions to 250°C and 400 bars and over the range of ionic strengths 0.2 - 5.5 and 0.2 - 19.2 mol·kg⁻¹, respectively. The results span the pressure and temperature of earlier volumetric studies and extend to higher molalities than reported previously. The relative densities have been fitted as apparent molar volumes (V&lt;sub&gt;Φ&lt;/sub&gt;) using the Pitzer ion-interaction treatment, with appropriate expressions chosen for the temperature- and pressure-dependence of the virial coefficients of the model. The results presented for NaCl(aq) are in good agreement with published results to 250°C. The results presented for CaCl₂(aq) are in good agreement with published values to approximately 125°C. Above 125°C the inter- and intralaboratory precision of the published data deteriorate and are often in very poor agreement with the data from this Study. The representation for V&lt;sub&gt;Φ&lt;/sub&gt; for CaCl₂(aq) was integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. CaCl₂ activity coefficients (γ±) have been derived to 250°C, 400 bars and 4 mol·kg⁻¹ using published fits of CaCl₂ activity coefficient data along the vapor saturation surface and the pressure dependence determined in this work. The volumetric data indicate that the mean ionic activity coefficient, γ±(CaCl₂), increases by a maximum of 32% at 400 bars, 250°C, and 4 mol·kg⁻¹ as compared with its value at saturation pressure. Relative densities were also measured for several ternary { NaCl+CaCl₂}(aq) solutions at 25 and 35°C and 1 atm. These results substantially expand the volumetric data base for ternary solutions. Based on the results of this study most of the previously reported 308.15 K density data in the ternary appear to contain large errors.","abstract_has_math":false,"creators":["Oakes, Charles Steger"],"institution":"Virginia Tech","degree_name":"Ph. D.","degree_level":"doctoral","degree_discipline":"Geological Sciences","degree_department":"Geological Sciences","school":null,"contributors":[],"advisors":[],"committee_chairs":["Bodnar, Robert J."],"committee_members":["Simonson, John M.","Hewitt, David A.","Tracy, Robert J.","Rimstidt, J. Donald"],"year":1992,"date_issued":"1992","date_published":"1992","updated_at":"2026-07-22T22:18:58Z","subjects":[],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-10102005-131612"],"render_values":[{"text":"etd-10102005-131612","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/39729","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Bodnar, Robert J."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Simonson, John M.","Hewitt, David A.","Tracy, Robert J.","Rimstidt, J. 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The results are in excellent agreement with published data along the NaCl-H₂O binary but show large discrepancies when compared to previous determinations of the ice liquidus along the CaCl₂-H₂O binary and in the NaCl-CaCl₂-H₂O ternary. At moderate to high salinities, isotherms cross the ice sub-field at lower total salt concentrations than previously reported. In addition, NaCl/(NaCl+CaCl₂) weight ratios estimated from hydrohalite- and ice-melting temperatures may be low by as much as 15%. Relative densities were measured for NaCl(aq) and CaCl₂(aq) solutions to 250°C and 400 bars and over the range of ionic strengths 0.2 - 5.5 and 0.2 - 19.2 mol·kg⁻¹, respectively. The results span the pressure and temperature of earlier volumetric studies and extend to higher molalities than reported previously. The relative densities have been fitted as apparent molar volumes (V<sub>Φ</sub>) using the Pitzer ion-interaction treatment, with appropriate expressions chosen for the temperature- and pressure-dependence of the virial coefficients of the model. The results presented for NaCl(aq) are in good agreement with published results to 250°C. The results presented for CaCl₂(aq) are in good agreement with published values to approximately 125°C. Above 125°C the inter- and intralaboratory precision of the published data deteriorate and are often in very poor agreement with the data from this Study. The representation for V<sub>Φ</sub> for CaCl₂(aq) was integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. CaCl₂ activity coefficients (γ±) have been derived to 250°C, 400 bars and 4 mol·kg⁻¹ using published fits of CaCl₂ activity coefficient data along the vapor saturation surface and the pressure dependence determined in this work. The volumetric data indicate that the mean ionic activity coefficient, γ±(CaCl₂), increases by a maximum of 32% at 400 bars, 250°C, and 4 mol·kg⁻¹ as compared with its value at saturation pressure. Relative densities were also measured for several ternary { NaCl+CaCl₂}(aq) solutions at 25 and 35°C and 1 atm. These results substantially expand the volumetric data base for ternary solutions. Based on the results of this study most of the previously reported 308.15 K density data in the ternary appear to contain large errors."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph. D."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["BTD"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Phase equilibria and volumetric properties for the system NaCl-CaCl₂-H₂O"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Bodnar, Robert J."],"dc:contributor.committeemember":["Simonson, John M.","Hewitt, David A.","Tracy, Robert J.","Rimstidt, J. Donald"],"dc:contributor.department":["Geological Sciences"],"dc:creator":["Oakes, Charles Steger"],"dc:date.accessioned":["2014-03-14T21:20:45Z"],"dc:date.available":["2014-03-14T21:20:45Z","2005-10-10"],"dc:date.issued":["1992"],"dc:description.abstract":["Low temperature phase relations in the ice-stable field of the system NaCl-CaCl₂-H₂O were determined under 1 atm. total pressure along the NaCl-H₂O and CaCl₂-H₂O binaries and along five pseudobinaries with constant NaCl/(NaCl+CaCl₂) weight ratios. The results are in excellent agreement with published data along the NaCl-H₂O binary but show large discrepancies when compared to previous determinations of the ice liquidus along the CaCl₂-H₂O binary and in the NaCl-CaCl₂-H₂O ternary. At moderate to high salinities, isotherms cross the ice sub-field at lower total salt concentrations than previously reported. In addition, NaCl/(NaCl+CaCl₂) weight ratios estimated from hydrohalite- and ice-melting temperatures may be low by as much as 15%. Relative densities were measured for NaCl(aq) and CaCl₂(aq) solutions to 250°C and 400 bars and over the range of ionic strengths 0.2 - 5.5 and 0.2 - 19.2 mol·kg⁻¹, respectively. The results span the pressure and temperature of earlier volumetric studies and extend to higher molalities than reported previously. The relative densities have been fitted as apparent molar volumes (V<sub>Φ</sub>) using the Pitzer ion-interaction treatment, with appropriate expressions chosen for the temperature- and pressure-dependence of the virial coefficients of the model. The results presented for NaCl(aq) are in good agreement with published results to 250°C. The results presented for CaCl₂(aq) are in good agreement with published values to approximately 125°C. Above 125°C the inter- and intralaboratory precision of the published data deteriorate and are often in very poor agreement with the data from this Study. The representation for V<sub>Φ</sub> for CaCl₂(aq) was integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. CaCl₂ activity coefficients (γ±) have been derived to 250°C, 400 bars and 4 mol·kg⁻¹ using published fits of CaCl₂ activity coefficient data along the vapor saturation surface and the pressure dependence determined in this work. The volumetric data indicate that the mean ionic activity coefficient, γ±(CaCl₂), increases by a maximum of 32% at 400 bars, 250°C, and 4 mol·kg⁻¹ as compared with its value at saturation pressure. Relative densities were also measured for several ternary { NaCl+CaCl₂}(aq) solutions at 25 and 35°C and 1 atm. These results substantially expand the volumetric data base for ternary solutions. Based on the results of this study most of the previously reported 308.15 K density data in the ternary appear to contain large errors."],"dc:description.degree":["Ph. D."],"dc:format.medium":["BTD"],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["etd-10102005-131612"],"dc:identifier.uri":["http://hdl.handle.net/10919/39729"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Phase equilibria and volumetric properties for the system NaCl-CaCl₂-H₂O"],"dc:type":["Dissertation"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Geological Sciences"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Ph. D."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:18:58Z"}