The molar enthalpies of solution and vapour pressures of saturated aqueous solutions of some ammonium salts

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Abstract

Vapour pressures of water over saturated solutions of ammonium bromide, ammonium dihydrogen phosphate, ammonium thiosulfate, ammonium persulfate, ammonium acetate, ammonium oxalate and ammonium tartrate were determined as a function of temperature. These vapour pressures were used to evaluate the water activities, osmotic coefficients and molar enthalpies of vaporization. Molar enthalpies of solution of ammonium bromide ΔsolHm (NH4Br, T = 293.97 K, m = 0.1030 mol · kg-1) = (17.4 ± 0.5) kJ · mol-1; ammonium hydrogen carbonate ΔsolHm (NH4HCO3, T = 293.06 K, m = 0.06372 mol · kg-1) = (26.4 ± 1.1) kJ · mol-1; ammonium dihydrogen phosphate ΔsolHm(NH4H2PO4, T = 297.08 K, m = 0.08774 mol · kg-1) = (15.0 ± 1.1) kJ · mol-1; ammonium phosphate trihydrate ΔsolHm((NH4)3PO4 · 3H2O, T = 296.29 K, m = 0.04960 mol · kg-1) = (24.1 ± 1.4) kJ · mol-1; ammonium thiosulfate ΔsolHm((NH4)2 S2O3, T = 293.86 K, m = 0.03410 mol · kg-1) = (15.8 ± 0.7) kJ · mol-1; ammonium oxalate monohydrate ΔsolHm ((NH4)2C2O4 · H2O, T = 296.99 K, m = 0.03401 mol · kg-1) = (35.0 ± 4.9) kJ · mol-1 and ammonium tartrate ΔsolHm((NH4)2C4 H4O6, T = 297.14 K, m = 0.02745 mol · kg-1) = (28.4 ± 0.6) kJ · mol-1 were determined calorimetrically.

Original languageEnglish
Pages (from-to)699-709
Number of pages11
JournalJournal of Chemical Thermodynamics
Volume35
Issue number5
DOIs
StatePublished - 1 Jan 2003

Keywords

  • Molar enthalpies of vaporization and solution
  • Osmotic coefficients
  • Saturated solutions
  • Vapour pressures
  • Water activities

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • General Materials Science
  • Physical and Theoretical Chemistry

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