The dissociation of phosphoric acid in NaCl and NaMgCl solutions at 25°C

J. Peter Hershey, Marino Fernandez, Frank J Millero

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Abstract

The pK1*, pK1* and pK3* for the dissociation of H3PO4 have been measured in NaCl solutions from 0.5 to 6m at 25°C. The results have been used to evaluate Pitzer interaction parameters ψ(NaClH2PO4)=-0.028±0.005, λ(NaH3PO4)=-0.075±0.025, θ(HPO4Cl)=0.105±0.009, θ(PO4Cl)=-0.59±0.02 and ψ(NaClHPO4)=-0.003±0.004, ψ(PO4NaClH)=0.110±0.008. These parameters yield values of pK1*, pK2* and pK3* in NaCl that agree with the measured values with average deviations of ±0.04, ±0.03 and ±0.05 in pK1*. Measurements of pK1* and pK2* were also made in NaMgCl solutions. These results have been used to evaluate β(O)(MgH2PO4)=-3.55±0.07,β(1)(MgH2PO4=-16.9±0.03, β(O)(MgH2PO4=-17.5±0.03 and β(1)(MgH2PO4)=27.4±0.8 at 25°C. The results for pK2* in NaMg-Cl solutions were also used to calculate log KMX*=3.2±0.1 for the formation of the ion pair MgHPO4o.

Original languageEnglish (US)
Pages (from-to)875-891
Number of pages17
JournalJournal of Solution Chemistry
Volume18
Issue number9
DOIs
StatePublished - Sep 1989

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phosphoric acid
dissociation
Ions
deviation
ions
interactions

Keywords

  • ion pairing
  • Phosphoric acid
  • Pitzer equations

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

The dissociation of phosphoric acid in NaCl and NaMgCl solutions at 25°C. / Peter Hershey, J.; Fernandez, Marino; Millero, Frank J.

In: Journal of Solution Chemistry, Vol. 18, No. 9, 09.1989, p. 875-891.

Research output: Contribution to journalArticle

Peter Hershey, J. ; Fernandez, Marino ; Millero, Frank J. / The dissociation of phosphoric acid in NaCl and NaMgCl solutions at 25°C. In: Journal of Solution Chemistry. 1989 ; Vol. 18, No. 9. pp. 875-891.
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abstract = "The pK1*, pK1* and pK3* for the dissociation of H3PO4 have been measured in NaCl solutions from 0.5 to 6m at 25°C. The results have been used to evaluate Pitzer interaction parameters ψ(NaClH2PO4)=-0.028±0.005, λ(NaH3PO4)=-0.075±0.025, θ(HPO4Cl)=0.105±0.009, θ(PO4Cl)=-0.59±0.02 and ψ(NaClHPO4)=-0.003±0.004, ψ(PO4NaClH)=0.110±0.008. These parameters yield values of pK1*, pK2* and pK3* in NaCl that agree with the measured values with average deviations of ±0.04, ±0.03 and ±0.05 in pK1*. Measurements of pK1* and pK2* were also made in NaMgCl solutions. These results have been used to evaluate β(O)(MgH2PO4)=-3.55±0.07,β(1)(MgH2PO4=-16.9±0.03, β(O)(MgH2PO4=-17.5±0.03 and β(1)(MgH2PO4)=27.4±0.8 at 25°C. The results for pK2* in NaMg-Cl solutions were also used to calculate log KMX*=3.2±0.1 for the formation of the ion pair MgHPO4o.",
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N2 - The pK1*, pK1* and pK3* for the dissociation of H3PO4 have been measured in NaCl solutions from 0.5 to 6m at 25°C. The results have been used to evaluate Pitzer interaction parameters ψ(NaClH2PO4)=-0.028±0.005, λ(NaH3PO4)=-0.075±0.025, θ(HPO4Cl)=0.105±0.009, θ(PO4Cl)=-0.59±0.02 and ψ(NaClHPO4)=-0.003±0.004, ψ(PO4NaClH)=0.110±0.008. These parameters yield values of pK1*, pK2* and pK3* in NaCl that agree with the measured values with average deviations of ±0.04, ±0.03 and ±0.05 in pK1*. Measurements of pK1* and pK2* were also made in NaMgCl solutions. These results have been used to evaluate β(O)(MgH2PO4)=-3.55±0.07,β(1)(MgH2PO4=-16.9±0.03, β(O)(MgH2PO4=-17.5±0.03 and β(1)(MgH2PO4)=27.4±0.8 at 25°C. The results for pK2* in NaMg-Cl solutions were also used to calculate log KMX*=3.2±0.1 for the formation of the ion pair MgHPO4o.

AB - The pK1*, pK1* and pK3* for the dissociation of H3PO4 have been measured in NaCl solutions from 0.5 to 6m at 25°C. The results have been used to evaluate Pitzer interaction parameters ψ(NaClH2PO4)=-0.028±0.005, λ(NaH3PO4)=-0.075±0.025, θ(HPO4Cl)=0.105±0.009, θ(PO4Cl)=-0.59±0.02 and ψ(NaClHPO4)=-0.003±0.004, ψ(PO4NaClH)=0.110±0.008. These parameters yield values of pK1*, pK2* and pK3* in NaCl that agree with the measured values with average deviations of ±0.04, ±0.03 and ±0.05 in pK1*. Measurements of pK1* and pK2* were also made in NaMgCl solutions. These results have been used to evaluate β(O)(MgH2PO4)=-3.55±0.07,β(1)(MgH2PO4=-16.9±0.03, β(O)(MgH2PO4=-17.5±0.03 and β(1)(MgH2PO4)=27.4±0.8 at 25°C. The results for pK2* in NaMg-Cl solutions were also used to calculate log KMX*=3.2±0.1 for the formation of the ion pair MgHPO4o.

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