07 - Gas Phase Calculations
This example corresponds to the “Example 7-Gas-Phase Calculations” from the Phreeqc manual. It can be retrieved from the Phreeqc Website.
This example demonstrates the capabilities of PHREEQC to model the evolution of gas compositions in equilibrium with a solution with a fixed (total) pressure or a fixed volume of the gas phase
Studies
This project contains 1 Studies.
PhreeqcStudy: “study_07 - Gas Phase Calculations”
Db used: “Phreeqc_dat” database
TITLE Example 7.--Organic decomposition with fixed-pressure and
fixed-volume gas phases
SOLUTION_MASTER_SPECIES
N(-3) NH4+ 0.0 N
SOLUTION_SPECIES
NH4+ = NH3 + H+
log_k -9.252
delta_h 12.48 kcal
-analytic 0.6322 -0.001225 -2835.76
NO3- + 10 H+ + 8 e- = NH4+ + 3 H2O
log_k 119.077
delta_h -187.055 kcal
-gamma 2.5000 0.0000
PHASES
NH3(g)
NH3 = NH3
log_k 1.770
delta_h -8.170 kcal
SOLUTION 1
EQUILIBRIUM_PHASES 1
Calcite
CO2(g) -1.5
SAVE solution 1
END
# Simulation 2: Decomposition of organic matter, CH2O(NH3).07,
# at fixed pressure of 1.1 atm
USE solution 1
GAS_PHASE 1 Fixed-pressure gas phase
-fixed_pressure
-pressure 1.1
CO2(g) 0.0
CH4(g) 0.0
N2(g) 0.0
H2O(g) 0.0
REACTION 1
CH2O(NH3)0.07 1.0
1. 2. 3. 4. 8. 16. 32 64. 125. 250. 500. 1000. mmol
END
# Simulation 3: Decomposition of organic matter, CH2O(NH3).07,
# at fixed volume of 23.19 L
USE solution 1
USE reaction 1
GAS_PHASE 1 Fixed volume gas phase
-fixed_volume
-volume 23.19
CO2(g) 0.0
CH4(g) 0.0
N2(g) 0.0
H2O(g) 0.0
-equilibrate 1
END
/n
Plots
This project contains 2 Plots.
Plot 1: “GasCompositionPlot”
Plot 2: “Pressure and Volume Plot”
