# PhreeqcUsers Discussion Forum

## Kinetics and Equilibrium => Kinetics => Topic started by: hamiderfani on January 03, 2018, 03:35:01 PM

Title: Kinetic Reaction for species
Post by: hamiderfani on January 03, 2018, 03:35:01 PM
Dear all,
I want to simulate the situation where an aquous solution (with defined composition) gets in contact with a mineral (kaolinite or dolomite) for a defined period of time (the time is so short, a differential time where no more steps are needed for kinetics calculations).
Water reacts with the mineral and based on saturation index of the mineral it dissolves or precipitates the mineral (in case of dissolution, the amount of mineral is more than enough). at last I want to get the final composition of aquous phase and amount of dissolved/precipitated mineral.
In case of equilibrium, the reaction time is not important as the reaction happens till equilibrium is reached but in terms of kinetics, time and surface area of the reaction are important factors which control the amount of dissolution/precipitation and final aquous phase composition.
1. What is the easiest way to define this simple system using rate, kinetics and ...?
2. As I have skimmed the examples with kinetic reactants, in all examples the user inserts the amount of available moles of reactants, is there any way to insert the amount of surface area available for the reaction to happen on? (this surface is assumed to be constant during the differential time, during which the reaction happens.

`RATESQtz10 area = PARM(1) # m^220 k = 1e-5 # mol/s/m^230 rate = area * k * (1 - SR("Quartz"))40 moles = rate * time50 SAVE molesENDSOLUTIONKINETICSQtz-formula SiO2-parms 1.0-step 1END`