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Current Project

Analytical Chemistry Division (V)


Number: 2006-010-1-500

Title: Adjustment, estimation and uses of equilibrium reaction constants in aqueous solution

Task Group
Igor V. Sukhno

Members: Vladimir Y. Buzko and Leslie D. Pettit

To prepare (and improve) programs to treat quantitatively the dependence of activity coefficients (and hence equilibrium constants) on ionic strength and on the presence of dissolved gases.To explore and test computer-based ways of displaying these effects graphically and the influence they will have on species distribution curves.

A previous IUPAC project (# 2000-003-1-500) has produced a suite of programs to study quantitatively the influence of ionic strength changes on equilibrium constants, with particular emphasis on using Specific Interaction Theory (SIT). In this project we propose to extend this work in the following ways:

  • To apply Pitzer parameters in a more general way to equilibria of environmental and industrial importance. Particular importance will be given to sea water and mixed fluids.
  • To extend and improve a database of published SIT and Pitzer-related parameters. This database may be accessed by all relevant programs in the suite and may be edited by the user.
  • Currently the package allows calculations on the effects of dissolved O2. This will be extended to cover other environmentally important gases (e.g. air, H2, N2, rare gases, N2O, CH4, and other paraffins
  • To explore and test ways of displaying graphically the relationship between ionic strength and temperature with activity coefficients, lg Kº and lg K;
  • To explore and test ways of displaying graphically the effects of errors on the relationships studied above.
  • To calculate, and demonstrate graphically, the effect of errors on species distribution curves.
  • To prepare a database of reliable literature values of the dependence of stability constants on temperature.

> download the entire suite > aq_solutions.zip (zip file - 6.52MB; update in April 2008) or access current version from: public.kubsu.ru/aquasolsoft/ and select 'Projects'


> July 2007 report update (pdf file - 10KB)

> Feb 2008 progress:
- SIT and Pitzer-related parameters published between June 2006 and January 2008 are being analyzed.
- A version of the SIT program to correct stability constants for changes in seawater salinity and in electrolyte mixtures is being tested.
- A program to calculate the solubilities of N2 and rare gases is being tested.
- A new version of project software is being released (Apr 2008):
> download the entire suite > aq_solutions.zip (zip file - 6.52MB) or access version from: public.kubsu.ru/aquasolsoft/ and select 'Projects' or from Academic Software (www.acadsoft.co.uk)

Last Update: 30 April 2008

<project announcement published in Chem. Int. Sep-Oct 2006>

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Page last modified 30 April 2008.
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