Let's create an alien biosphere!

[Schiaparelliorbust]

Theoretically, yes, but they'll have no reason to unless they use it to get energy.

They might evolve it when they get to land if the formamide from the water isn't enough.

[MathAndCode]

They might evolve it when they get to land if the formamide from the water isn't enough.

Yes, but photosynthesis would likely start at the ocean surface.

[Schiaparelliorbust]

Yes, but photosynthesis would likely start at the ocean surface.

I know that. I'm just saying it could happen. Could you please list the current chemical ecology on the planet (if we've finished it)?

[MathAndCode]

I know that. I'm just saying it could happen. Could you please list the current chemical ecology on the planet (if we've finished it)?

How much does this help?

Volcanoes will emit sulfur compounds, carbon dioxide, and carbon monoxide into the atmosphere. The sulfur oxides produced with react with the water vapor in the air to produce sulfuric oxyacids, which will be neutralized by the ammonia to form sulfur oxyanions, which will then to to the surface via precipitation.
Formamide will be formed in the atmosphere from ammonia reacting with carbon monoxide and water reacting with hydrogen cyanide, be delivered to the surface via precipitation, and enter the oceans. At the bottom of the oceans, it will be converted by solid acid catalysts or heat from hydrothermal vents back into carbon monoxide and ammonia or into water and hydrogen cyanide. The first two of these compounds are gases at any temperature at which water is not solid (at least at standard pressure) and can only be dissolved in water in limited quantities, so they will reenter the atmosphere. The water will reenter the atmosphere through evaporation. Hydrogen cyanide would be liquid at the temperatures in most of Earth's ocean water, and it is miscible with water, but its vapor pressure is much higher than that of water, so it will evaporate into the atmosphere at a much greater rate that that of water. There will also be a reversible reaction where water and isocyanic acid interchange with ammonia and carbon dioxide. Isocyanic acid will be a similar case to hydrogen cyanide in the sense that its boiling point is near room temperature, and its vapor pressure is much higher than that of water (which is related to its lower boiling point), so it will enter the atmosphere from the oceans much more readily than water.

[Schiaparelliorbust]

How much does this help?

Volcanoes will emit sulfur compounds, carbon dioxide, and carbon monoxide into the atmosphere. The sulfur oxides produced with react with the water vapor in the air to produce sulfuric oxyacids, which will be neutralized by the ammonia to form sulfur oxyanions, which will then to to the surface via precipitation.
Formamide will be formed in the atmosphere from ammonia reacting with carbon monoxide and water reacting with hydrogen cyanide, be delivered to the surface via precipitation, and enter the oceans. At the bottom of the oceans, it will be converted by solid acid catalysts or heat from hydrothermal vents back into carbon monoxide and ammonia or into water and hydrogen cyanide. The first two of these compounds are gases at any temperature at which water is not solid (at least at standard pressure) and can only be dissolved in water in limited quantities, so they will reenter the atmosphere. The water will reenter the atmosphere through evaporation. Hydrogen cyanide would be liquid at the temperatures in most of Earth's ocean water, and it is miscible with water, but its vapor pressure is much higher than that of water, so it will evaporate into the atmosphere at a much greater rate that that of water. There will also be a reversible reaction where water and isocyanic acid interchange with ammonia and carbon dioxide. Isocyanic acid will be a similar case to hydrogen cyanide in the sense that its boiling point is near room temperature, and its vapor pressure is much higher than that of water (which is related to its lower boiling point), so it will enter the atmosphere from the oceans much more readily than water.

That helps of course (I had read it earlier today), but I was more asking for the current biological chemistry.

[MathAndCode]

That helps of course (I had read it earlier today), but I was more asking for the current biological chemistry.

First of all, which of the mentioned reactions do you like, and can you think of any others?

[Schiaparelliorbust]

First of all, which of the mentioned reactions do you like, and can you think of any others?

I only found these two that I want:
HCN+NH₃→N₂+CH₄
CH₃NO+HNCO→N₂+CO₂+CH₄
I also found this one:
2HCN→N₂+C₂H₂
We could have it, but you had said that the former of the above reactions was more efficient. I can't really think of anything else.

[MathAndCode]

I only found these two that I want:
HCN+NH₃→N₂+CH₄
CH₃NO+HNCO→N₂+CO₂+CH₄
I also found this one:
2HCN→N₂+C₂H₂
We could have it, but you had said that the former of the above reactions was more efficient. I can't really think of anything else.

Yes, let's not use the ethyne-making reaction. Both of the other reactions make methane, and hydrothermal vents expel it, so maybe we should try to make a reaction from that, although it's possible that this isn't feasible in the reducing environment. (It can be combined with carbon dioxide to make acetic acid, but that's not very exothermic.)
Also, a while ago, you suggested CO+H₂O→CO₂+H₂, which I like. The hydrogen could potentially be used to synthesize ammonia, which is exothermic.
Lastly, I think that we should attempt to use more compounds from the hydrothermal vents in reactions.

[Schiaparelliorbust]

Yes, let's not use the ethyne-making reaction. Both of the other reactions make methane, and hydrothermal vents expel it, so maybe we should try to make a reaction from that, although it's possible that this isn't feasible in the reducing environment. (It can be combined with carbon dioxide to make acetic acid, but that's not very exothermic.)

The methane can be burned once oxygen comes and if photosynthesizers can still use it (assuming they make oxygen) they can use the methane they make themselves.

Also, a while ago, you suggested CO+H₂O→CO₂+H₂, which I like. The hydrogen could potentially be used to synthesize ammonia, which is exothermic.

Oh yeah, thanks. I had forgotten about that one. Would the reaction be 3H₂+N₂ → 2NH₃?

Lastly, I think that we should attempt to use more compounds from the hydrothermal vents in reactions.

You mean like metals?

[MathAndCode]

Oh yeah, thanks. I had forgotten about that one. Would the reaction be 3H₂+N₂ → 2NH₃?

Yes, that's correct. That organism will thrive near the surface due to atmospheric nitrogen as long as there's geologic activity, but if that fades away, then it will have to figure out how to make elemental hydrogen. The most obvious method will be by splitting water, which will also result in elemental oxygen.

You mean like metals?

The problem with that is that they are already oxidized, so it will be difficult to get much more energy from them. However, hydrothermal vents also expel hydrogen sulfide, which looks more attractive for chemosynthesis. Biblaridion's series uses it to help make formaldehyde, but the reaction isn't very exothermic.

[Schiaparelliorbust]

Oh yeah, thanks. I had forgotten about that one. Would the reaction be 3H₂+N₂ → 2NH₃?

Yes, that's correct. That organism will thrive near the surface due to atmospheric nitrogen as long as there's geologic activity, but if that fades away, then it will have to figure out how to make elemental hydrogen. The most obvious method will be by splitting water, which will also result in elemental oxygen.

Maybe they can do limited electrolysis with light? It would be something like a partial photosynthesis (maybe that's not the correct term for it). There would be two steps CO+H₂O→CO₂+H₂ and 3H₂+N₂ → 2NH₃.

The problem with that is that they are already oxidized, so it will be difficult to get much more energy from them. However, hydrothermal vents also expel hydrogen sulfide, which looks more attractive for chemosynthesis. Biblaridion's series uses it to help make formaldehyde, but the reaction isn't very exothermic.

What other substances do they produce?

[MathAndCode]

Maybe they can do limited electrolysis with light? It would be something like a partial photosynthesis (maybe that's not the correct term for it). There would be two steps CO+H₂O→CO₂+H₂ and 3H₂+N₂ → 2NH₃.

I suppose that that's a viable alternative.

What other substances do they produce?

elemental sulfur and water

[Schiaparelliorbust]

elemental sulfur and water

What is elemental sulfur useful for? Would they likely use it for oxidising?

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What is elemental sulfur useful for? Would they likely use it for oxidising?

They could react it with hydrogen to make hydrogen sulfide, but that would only be mildy exothermic. None of the possibilities that I can think of off of the top of my head look particularly attractive.

[Schiaparelliorbust]

They could react it with hydrogen to make hydrogen sulfide, but that would only be mildy exothermic. None of the possibilities that I can think of off of the top of my head look particularly attractive.

They don't necessarily need to use it to make energy. I don't know much, but I bet they could use it for something else.

[MathAndCode]

They don't necessarily need to use it to make energy. I don't know much, but I bet they could use it for something else.

It could be used for shells, but there are other materials that have advantages over sulfur for that purpose.

[Schiaparelliorbust]

It could be used for shells, but there are other materials that have advantages over sulfur for that purpose.

I was thinking of using it structurally, but then I thought it wouldn't be worth it. Could it be used in their biochemistry?

[MathAndCode]

I was thinking of using it structurally, but then I thought it wouldn't be worth it. Could it be used in their biochemistry?

Yes, but they could more easily get sulfur from other forms.

[Schiaparelliorbust]

Yes, but they could more easily get sulfur from other forms.

Like in the form of H₂S from the atmosphere? But they would not be able to access it much that deep down

[MathAndCode]

Like in the form of H₂S from the atmosphere? But they would not be able to access it much that deep down

Hydrothermal vents emit hydrogen sulfide.

[Schiaparelliorbust]

Hydrothermal vents emit hydrogen sulfide.

Sorry, I forgot that. I was sleepy at the time.

[MathAndCode]

Sorry, I forgot that. I was sleepy at the time.

It turns out that giant tube worms living near hydrothermal vents have bacterial symbiotes that oxidize hydrogen sulfide to sulfite then use the energy from converting sulfite to sulfate to recharge AMP into ATP and use the extra electrons to power an electron transport chain. The organisms might be able to do something like that eventually, although it will take them a while to evolve it.

[Schiaparelliorbust]

It turns out that giant tube worms living near hydrothermal vents have bacterial symbiotes that oxidize hydrogen sulfide to sulfite then use the energy from converting sulfite to sulfate to recharge AMP into ATP and use the extra electrons to power an electron transport chain. The organisms might be able to do something like that eventually, although it will take them a while to evolve it.

So have we decided on the reactions?

[MathAndCode]

So have we decided on the reactions?

There are two more things (that I can think of) that we should do concerning the reactions. First, earlier, you suggested the reaction CO+H₂O→CO₂+H₂. While this is significantly exothermic and would likely happen, the hydrogen gas could be used for other reactions. The synthesis of ammonia is one example, but that would likely only be feasible close to the surface. An example that could more feasibly happen underwater is, CO₂+2H₂→2H₂O+C, which is also exothermic. The two reactions could be combined to yield CO+H₂→H₂O+C or 2CO→CO₂+C. The creatures might then excrete this carbon to form a carbon shell. There are probably reactions that could use it, but we don't have to have it get used up.
Also, if we want the atmosphere to have a significant amount of dioxygen eventually, we should make sure that at least one photosynthetic reaction will lead to that. However, even if there isn't a way to motivate a reaction that will allow for an immediate transition, it's possible that we could change the environment in multiple stages such that a later stage could more realistically lead to the creatures expelling dioxygen than an earlier stage. If the environment gradually becomes more oxidizing, this could also prevent a single massive extinction event due to the introduction of oxygen, but this isn't given.



Edit: I just realized that combining water and carbon monoxide into formic acid is significantly exothermic. Organisms could also use this to create energy, but it might also happen to carbon monoxide dissolved in the oceans abiotically.

[Schiaparelliorbust]

There are two more things (that I can think of) that we should do concerning the reactions. First, earlier, you suggested the reaction CO+H₂O→CO₂+H₂. While this is significantly exothermic and would likely happen, the hydrogen gas could be used for other reactions. The synthesis of ammonia is one example, but that would likely only be feasible close to the surface. An example that could more feasibly happen underwater is, CO₂+2H₂→2H₂O+C, which is also exothermic. The two reactions could be combined to yield CO+H₂→H₂O+C or 2CO→CO₂+C. The creatures might then excrete this carbon to form a carbon shell. There are probably reactions that could use it, but we don't have to have it get used up.

Like a graphite shell? Also 2CO→CO₂+C is reversible.

Also, if we want the atmosphere to have a significant amount of dioxygen eventually, we should make sure that at least one photosynthetic reaction will lead to that. However, even if there isn't a way to motivate a reaction that will allow for an immediate transition, it's possible that we could change the environment in multiple stages such that a later stage could more realistically lead to the creatures expelling dioxygen than an earlier stage. If the environment gradually becomes more oxidizing, this could also prevent a single massive extinction event due to the introduction of oxygen, but this isn't given.

I mean O₂ is a relatively simple molecule. If we find an exothermic enough reaction that creates it, there's no reason they shouldn't use it. Also, an extinction event would probably kill a lot of microorganisms, but there isn't anything really bad about that. Many non-oxygen producing photosynthesizers might go extinct, but sulfate-reducing bacteria could probably still survive near hydrothermal vents, as is the case today. If you really don't want an oxygen shock, how do you propose to implement it?