## Abstract

The apparent molal volumes (φ_{v}) and adiabatic compressibilities [φ_{K(S)}] of La_{2}(SO_{4})_{3} solutions have been determined from density and sound speed data at 25°C. The large positive deviations of φ_{v} and φ_{K(S)} of La_{2}(SO_{4})_{3} from the limiting law have been attributed to the formation of the ion pair LaSO_{4}^{+}. The observed values of φ_{v} and φ_{K(S)} have been used to estimate the change in the apparent molal volume and adiabatic compressibility for the formation of LaSO_{4}^{+} from {Mathematical expression} where φ{symbol}(2La^{3+}, 3SO_{4}^{2-}) is the apparent molal volume or adiabatic compressibility of the free ions, and α is the degree of association. The value of {Mathematical expression} and {Mathematical expression} at infinite dilution are in reasonable agreement with the values determined from the high-pressure conductance data of Fisher and Davis. The number of hydrated water molecules (ca. 11) associated with the formation of LaSO_{4}^{+} determined from the volume and compressibility data are in good agreement.

Original language | English (US) |
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Pages (from-to) | 589-607 |

Number of pages | 19 |

Journal | Journal of Solution Chemistry |

Volume | 6 |

Issue number | 9 |

DOIs | |

State | Published - Sep 1 1977 |

## Keywords

- Lanthanum sulfate
- adiabatic apparent molal compressibility
- apparent molal volume
- density
- electrostriction
- hydration number
- ion pair
- magnetic float densimeter
- sound velocimeter

## ASJC Scopus subject areas

- Biophysics
- Biochemistry
- Molecular Biology
- Physical and Theoretical Chemistry