A Comparison of Computerized Chemical Models for Equilibrium Calculations in Aqueous Systems
Contributors
Other:
Abstract
A survey of computer programs which are currently being used to calculate the distribution of species in aqueous solutions, especially natural waters, has been made in order to 1) provide an inventory of available programs with a short description of their uses, 2) compare the consistency of their output for two given test solutions and 3) identify major weaknesses or problems encountered from their use. More than a dozen active programs which can be used for distribution of species and activity calculations for homogeneos equilibria among the major anions and cations of natural waters have been inventoried. Half of these programs can also accept several trace elements including Fe, Al, Mn, Cu, Ni, Zn, Cd, Pb, Ag, Hg, As, Ba, Sr, and B. Consistency between programs was evaluated by comparing the log of the molal concentrations of free ions and complexes for two test solutions: a hypothetical seawater analysis and a hypothetical river water analysis. Comparison of the free major ion concentrations in the river water test case shows excellent agreement for the major species. In the seawater test case there is less agreement and for both test cases the minor species commonly show orders of magnitude differences in concentrations. These differences primarily reflect differences in the thermodynamic data base of each chemical model although other factors such as activity coefficient calculations, redox assumptions, temperature corrections, alkalinity corrections and the number of complexes used all have an affect on the output.
Additional Information
This chapter not subject to U.S. copyright. Published 1979 American Chemical Society. Received November 16, 1978. Publication Date (Print): March 19, 1979.Attached Files
Published - bk-1979-0093_2Ech038.pdf
Files
bk-1979-0093_2Ech038.pdf
Additional details
Identifiers
- Eprint ID
- 77654
- Resolver ID
- CaltechAUTHORS:20170523-095954454
Dates
- Created
-
2017-05-23Created from EPrint's datestamp field
- Updated
-
2021-11-15Created from EPrint's last_modified field
Caltech Custom Metadata
- Series Name
- ACS Symposium Series
- Series Volume or Issue Number
- 93