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Dissociation constant of aqueous trifluoroacetic acid by cryoscopy and conductivity

Abstract

The dissociation constant of trifluoroacetic acid in aqueous solution has been determined at 25°C by electrical conductivity (0.65 mol-l−1) and at 0°C by cryoscopy (1.05 mol-l−1) and electrical conductivity (0.98 mol-l−1). The good agreement between the values of the constant determined by cryoscopy and conductivity at 0°C lends confidence to the value at 25°C determined by electrical conductivity. The constant determined at 25°C is in reasonable agreement with values determined by differential refractometry (0.92 mol-l−1) and from acidity function data (0.80 mol-l−1) reported by other workers. This work renews confidence in the electrical conductivity method for determining dissociation constants of moderately strong acids.

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Milne, J.B., Parker, T.J. Dissociation constant of aqueous trifluoroacetic acid by cryoscopy and conductivity. J Solution Chem 10, 479–487 (1981). https://doi.org/10.1007/BF00652082

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Key words

  • Trifluoroacetic acid
  • dissociation constant
  • cryoscopy
  • electrical conductivity
  • ionization constant
  • acidity