# PhreeqcUsers Discussion Forum

## Beginners => PHREEQC basics => Topic started by: frenzy_geochem on April 02, 2020, 01:00:57 PM

Title: Using H2S output Solution 1 in Solution 2
Post by: frenzy_geochem on April 02, 2020, 01:00:57 PM
Hii all,

Today, I got stuck on a little problem. I want to try and simulate how H2S(g) created from Solution 1 reacts with Solution 2. I cannot put 'USE solution 1' as I want to keep the solutions seperated. It is only the H2S(g) I want to add to Solution 2. When that has happened, I want to heat solution 2 (but I don't think that is a problem). Any ideas?

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`PHASES      H2S(g)        H2S  =  + 1.0000 H+ + 1.0000 HS-             log_k    -7.9759   delta_h 1.08  kcal       Fix_pH        H+ = H+        log_k 0SOLUTION 1-water 0.0155temp 25pH -0.15Na 1.29S(-2) 0.645S(6) 0.71ENDEQUILIBRIUM_PHASESFix_pH   -7 NaOH 10SOLUTION 2-water 0.04temp 25pH 2Fe(+3) 0.3Cl 0.9ENDREACTION_TEMPERATURE 1        25.0 85.0 in 12 stepsUSE Solution 2USE Reaction_temperature 1END`
Title: Re: Using H2S output Solution 1 in Solution 2
Post by: dlparkhurst on April 02, 2020, 04:16:44 PM
You haven't created any H2S(g) with solution 1. You need to use either EQUILIBRIUM_PHASES or GAS_PHASE to partition H2S(g) out of solution into a gas phase. If the gas evolves to a known partial pressure, you could use EQUILIBRIUM_PHASES. If the gas evolves into a fixed volume (or fixed pressure), you could use GAS_PHASE.

Here is one experiment where 1 L (kg water) evolves H2S(g) into 1 liter of head space.

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`SOLUTION 1-water 0.0155temp 25pH -0.15Na 1.29S(-2) 0.645S(6) 0.71ENDUSE solution 1GAS_PHASE 1    -fixed_volume    -pressure 1    -volume 1    -temperature 25    H2S(g)    0SAVE gas_phase 1ENDSOLUTION 2USE gas_phase 1END`