React Fixed Mass of Gas

[MBOTZ]

I am trying to react a fixed mass of gas with a solution.  For example, I'd like to add 1.00 gram of oxygen gas to the system, to determine how much of the 1.00 gram will dissolve into the solution.  Only a small amount would dissolve into 1.00 kg of H20.  But REACT is adding all of the oxygen into the solution, regardless of the actual solubility limit of O2(aq).  How can I limit the amount of O2 gas that will dissolve into solution according to the solubility?  I don't want to fix the fugacity, since there is only a limited supply of oxygen gas.  This would be similar to reacting a mineral, where some portion dissolves (according to its solubility) and the remainder of the mineral stays in the solid phase.  Thanks.

[Jia Wang]

Hello,

The simple reactant pathway changes the composition of the system in increments of the species that you wish to add to it. If you're setting an amount of O2 gas under simple reactants, React alters the system incrementally by adding O2 gas. Unlike minerals, gases in the GWB do not have a saturation limit. Please note that the software itself does not keep track of the gas phase volume. 

 

Hope this helps,
Jia Wang
Aqueous Solutions LLC

 

[MBOTZ]

Thank you Jia.  If I understand correctly, it is not possible to react a fixed mass of gas until its saturation is reached in the solution.  The options are 1) all of the gas will be added to solution regardless of its solubility, or 2) a fixed gas partial pressure can be specified and this will be absorbed into solution up to its solubility.  Is this correct?

[Jia Wang]

Hello,

If you use simple reactant, the species added simply changes the composition of the system. The applications do not have a gas saturation limit in the way as mineral, as the GWB applications do not track the volume of gas. You can set the fugacity of a gas, which then the program will calculate the amount of the dissolved species in equilibrium with the specified fugacity. Using sliding paths in React, you can adjust the gas fugacity from a starting value to a final value. Please see section 3.6 Sliding activity and fugacity in the Reaction Modeling Guide for more information. 

 

Best regards,

Jia