Saturated solution of H2S in water can be prepared by bubbling H2S gas into water untill no more dissolves.

Hi Dr R. Rihan . A saturated solution of hydrogen sulfide in water can be prepared by bubbling H2S gas into water until no more dissolves. See the link: https://www.topperlearning.com/answer/a-saturated-solution-of-hydrogen-sulfide-in-water-can-be-prepared-by-bubbling-h2s-gas-into-water-until-no-more-dissolves-calculate-the-molality-of-thi/rke6zgk11

Thanks Dr. Virendra and Dr. Aref for your participation and help.

I am trying to avoid the bubbling process for safety issues by looking for an alternative process.

If bubbling H2S gas is the only way, what is the save process of doing that?.

Dear R. Rihan thank you for posting this interesting question on RG. I fully agree with Virendra and Aref in that bubbling H2S through water is the easiest and most straightforward method for preparing a saturated solution. Just observe the absorption of the gas and stop when the H2S is not absorbed any more. You certainly know about the high toxicity of H2S, but the prodecure is safe when it is carried out in a well-ventilated fume hood.

For other potentially helpful answer please also have a look at the following closely related question which has been asked earlier on RG:

What is the most efficient procedure for producing an aqueous solution of hydrogen sulfide in water?

https://www.researchgate.net/post/What-is-the-most-efficient-procedure-for-producing-an-aqueous-solution-of-hydrogen-sulfide-in-water

(4 answers)

Good luck with your work and best wishes!

Thanks Prof. Edelmann for your valuable information. How can we observe the absorption of the gas and realizing that the gas is not absorbed any more.

Dear R. Rihan many thanks for your kind response and question. Just let a slow stream of H2S bubble through the specified amount of water. First you will observe that the bubbles become smaller or even disappear as they move through the water as the H2S is absorbed / dissolved. At some stage you will see that the gas bubbles move through the water unchanged. This is the point when the solution is saturated.

Dear Prof. Edelmann, thank you very much for your kind response and your help.

Dear Professors, I have the following two inquiries and I will be gratitude if you can help in this regards:

1. What is the concentration, in PPM, when the NACE Solution ‘A’ become saturated with H2S?

2. What is the purity or the concentration of the H2S gas in the gas cylinder that is used for bubbling the H2S gas in the solution. Should the gas cylinder contain pure H2S gas or can the cylinder be of mixed gases H2S and Nitrogen. If a cylinder of mixed gases (H2S and N2) can be used, what is the minimum concentration of H2S required in order to saturate the solution with H2S.

Dear R. Rihan many thanks for your kind response and questions. A very detailed advice regarding the use of H2S / N2 gas mixtures has been provided by Stephen N Smith as an answer to the following closely related RG question:

What is the most efficient procedure for producing an aqueous solution of hydrogen sulfide in water?

https://www.researchgate.net/post/What-is-the-most-efficient-procedure-for-producing-an-aqueous-solution-of-hydrogen-sulfide-in-water

I'm sure that this will be really helpful. It might also be worth a try to check if someone in your institution still owns an old "Kipp's apparatus" (https://en.wikipedia.org/wiki/Kipp%27s_apparatus). This is an excellent device to make H2S yourself in small and defined quantities.

Good luck and best wishes, Frank Edelmann

Dear Prof. Edelmann, thank you very much for your kind response.

Hi Rihan, some comments for you to be aware of:

1)H2S is extremely toxic, it must be handled in a dedicated lab.

2)The concentration of H2S in the solution is controlled by the partial pressure of H2S in the gas phase and temperature. Partial pressure of H2S in a gas mixture depends on total pressure and concentration of H2S in the mixture.

3)H2S reacts with dissolved oxygen in water yielding elemental sulfur, thiosulfates, among others, which affects both the corrosion rate of metals and the hydrogen absorption reactions. First step would definitely be to properly deareate the solution with pure nitrogen.

Hope this helps

Thanks Prof. Kappes for your valuable information.