Model IV: Inputs and Outputs for Parametric Calculations (Chemical Composition)

The model inputs are essentially the same as those for the comprehensive type calculation, but with the ionic composition of the system varied over a user-specified range. First, the initial system composition (i.e., amounts of each ion and ammonia present) is entered by the user, followed by a pair of ions that will be substituted one for the other, and then the range of amounts. In order to maintain overall charge neutrality, only a cation can be substituted for a cation, and an anion for an anion.

The organic composition of the system (if any compounds have been included) can not be varied

Take the following example: starting with a system containing 2 moles of H+, and 1 mole of SO42−, we substitute NO3 for the SO42− from 50 mole% of the original 1 mole of SO42− present up to 100 mole%. In carrying out the substitution we have to take account of the differing charge magnitudes of the two anions. The initial substitution in this example is for 50 mole%, or 0.5 moles. To maintain charge balance, this is replaced by 1.0 moles of NO3. The final substitution, of 100 mole% of the SO42−, yields a system containing 2 moles of H+ and 2 moles of NO3.

In the same way as for the other parametric calculations, the output is flexible with a choice between the normal mode used for the single-problem calculations, column mode (useful for pasting of results into other programs), and graphs. The input fields and output quantities are described below.



The on-line E-AIM models have three output modes: normal, column, and graph. All results are tested for thermodynamic consistency. Follow the links below for descriptions of their presentation, and the meanings of the various calculated quantities.