Adiabatic partial molal compressibilities of electrolytes in 0.725 m NaCl solutions at 25 °C

Frank J. Millero, Ana Kembro, Antonio Lo Surdo

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11 Scopus citations


The apparent molal adiabatic compressibilities (φK) of 29 electrolytes have been determined in the medium of 0.725 m NaCl from sound speed measurements. The values of φK have been extrapolated to infinite dilution to yield partial molal adiabatic compressibilities (K̄*0) in 0.725 m NaCl. The experimentally derived values of K̄*0 are compared to those predicted from binary solution data by using the ionic strength principle, Young's rule, and the specific interaction model For electrolytes with a common cation (Na+) or anion (Cl-) the specific interaction model and Young's rule predict similar values of k̄*0 (±2 × 10-4 cm3 mol-1 bar-1) and better estimates than the ionic strength principle. The compressibilities of mixing electrolytes (ΔKm) are quite small (less than 2 × 10-4 cm3 mol-1 bar-1). The values of ΔKm for electrolytes with a common cation (NaX + NaCl) and anion (MCl + NaCl) at I = 0.725 determined from our results correlate reasonably with the volume of mixing The compressibility and volume changes of transferring various ions from water to 0.725 m NaCl were found to correlate in a linear manner (104ΔK̄trans = -0.5 + 4.517ΔV̄trans, σ = 1.8 × 10-4 cm3 mol-1 bar-1).

Original languageEnglish (US)
Pages (from-to)2728-2734
Number of pages7
JournalJournal of physical chemistry
Issue number21
StatePublished - Dec 1 1980

ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry


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