Correction for solute/solvent interaction extends accurate freezing point depression theory to high concentration range

Gary D. Fullerton, Carl R. Keener, Ivan L. Cameron

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

The authors describe empirical corrections to ideally dilute expressions for freezing point depression of aqueous solutions to arrive at new expressions accurate up to three molal concentration. The method assumes non-ideality is due primarily to solute/solvent interactions such that the correct free water mass Mwc is the mass of water in solution Mw minus I·Ms where Ms is the mass of solute and I an empirical solute/solvent interaction coefficient. The interaction coefficient is easily derived from the constant in the linear regression fit to experimental plot of Mw Ms as a function of 1/ΔT (inverse freezing point depression). The I-value, when substituted into the new thermodynamic expressions derived from the assumption of equivalent activity of water in solution and ice, provides accurate predictions of freezing ppoint depression (±0.05°C) up to 2.5. molal concentration for all the test molecules evaluated; glucose, sucrose, glycerol and ethylene glycol. The concentration limit is the approximate monolayer water coverage limit for the solutes which suggests that direct solute/solute interactions are nergligible below this limit. This is contrary to the view of many authors due to the common practice of including hydration forces (a potential added to the hard core atomic potential) in the interactions potential between solute particles. When this is recognized the two viewpoints are in fundamental agreement.

Original languageEnglish (US)
Pages (from-to)217-235
Number of pages19
JournalJournal of Biochemical and Biophysical Methods
Volume29
Issue number3-4
DOIs
StatePublished - Dec 1994
Externally publishedYes

Keywords

  • Activity coefficient
  • Aqueous solution
  • Freezing point depression
  • Nonideality
  • Solution theory
  • Solvent structuring

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry

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