I am writing a story involving a hypothetical chemical reaction

[Conor Sullivan]

Hello, this is my first posting on this forum. I enjoyed Chemistry in high school, though the arts were where my abilities drew me.

I've learned that a ratio of 2 hydrogen to 1 oxygen, when ignited by a certain amount of heat, will create a small amount of water. I will give a brief outline on the hypothetical situation in my story which involves a mixture of hydrogen and oxygen on a grand scale, and I come to ask if this is plausible, or if some factors may need to be altered in order to make it a possible real scenario.

This takes place on the Earth approximately 100000 (more or less) years from now. The Earth has gone through another flood in reaction to global warming and ice caps melting, and beyond that, after flooding, the overheating has caused the water to evaporate up until when the story takes place, when the Earth has dried to the point of the oceans being at about half (more or less) their current depth.

The scenario is, a character is entering a cave where he will open a chest. In the cave there will be a very tight fracture line that leads to a hydrogen gas deposit below ground. I have learned that granite and olivine contain a large amount of hydrogen, so it is a possibility that the cave will be made of such rock. When he opens the chest, there will be some kind of mechanism that creates a spark, or ignites the whole cave (depending on the amount of heat needed) that will cause a reaction between the escaping hydrogen and the oxygen in the air. The outcome I desire from this is, because of the enormity of the hydrogen gas deposit underground, a reaction takes places that causes an enormous amount of water to be produced, enough to cause the oceans to rise significantly, enough to encourage a massive boost in growth of life on Earth from the new abundance of H2O. I hypothesize that the initial explosive reaction of the gases would demolish the cave and break the fracture line open to allow a greater reaction to take place, in order to basically create a gigantic tidal wave of water.

My questions are,
1.Is it plausible for there to be the proper concentration of oxygen in the air to provide the reaction?

2.Could there be an initial explosion strong enough to break open the fracture line, and what kind of heat would be needed? Just a tiny spark, or more? One initial spark, or a consistent flame?

3.If the reaction is possible, what size of water supply could it create, and how quickly? Would it depend upon the speed of the hydrogen releasing from the deposit to where water would basically appear from the air in the general area where the two gases meet?

I suppose this is a "science fiction" story, but optimally I am looking to create the most realistic world I can. I really appreciate anyone reading and considering. I look to the studious scientific community for their insight. Thanks!

 

[DaveC426913]

Check out the Hindenburg disaster, that's probably the largest, fastest combustion of hydrogen under uncontrolled circumstances that we have a record of.

1.Is it plausible for there to be the proper concentration of oxygen in the air to provide the reaction?

Yes. Given a spark, concentrated hydrogen will burn enthusiastically, if supplied with in air. But...

2.Could there be an initial explosion strong enough to break open the fracture line, and what kind of heat would be needed?

The initial size of the ignition is irrelevant to the destructive force of the explosion. Once lit, hydrogen combustion is self-sustaining, but ...

Just a tiny spark, or more? One initial spark, or a consistent flame?

Pretty sure an initial spark is sufficient - ideally. But...

The crux of the whole issue is the sufficient mixing of air and hydrogen. It would be tricky to arrange a circumstance where there is a sufficient amount of H mixed sufficiently uniformly with air in a sufficiently large volume - before being ignited.

(This is why natural gas derricks have a flame going all the time. So that any escaping gas is ignited harmlessly - i.e. before it can reach a deadly level.)

Would it depend upon the speed of the hydrogen releasing from the deposit to where water would basically appear from the air in the general area where the two gases meet?

Your fissure will act as a supply of hydrogen, like a busted gas line in a house. It will burn where it comes in contact - and mixes with - air -essentially a giant blowtorch - very much like a wildfire at an oil rig. The flame will create a rising cloud of steam. Eventually, that steam will precipitate out as mist and possibly rain.

Even if a very large fissure opened and released a lot of gas, it would not immediately cause sufficient mixing to result in an instant fireball. It would essentially only burn at the interface between hydrogen and air. That's the big rate-limiting factor for the whole scenario.

 

[Conor Sullivan]

Thanks a lot for the advice! So a tidal wave scenario wouldn't be likely, though with the water escaping from say a huge flame that erupted could be a trigger for a great deal of moisture that could eventually precipitate upon the Earth long enough to reach my final conclusion of a boost in life on the planet. I am sure that is a stretch, considering the probable amount of hydrogen escaping the fissure. My character will be striking two pyrite statues together, as depicted on hieroglyphs on the cave wall, that will cause the initial spark. I am thinking there will be enough hydrogen escaping to affect his mental state, though I may need to brainstorm another way the fissure can truly break and release an amount of hydrogen that would cause a planetary rainfall. Something with a large earthquake magnitude.

 

[Borek]

While you are concentrating on the reaction you are missing the more important points: the very idea of "hydrogen gas deposit" in completely unrealistic (yes, some rocks do contain hydrogen, you contain a lot of hydrogen too, but it doesn't mean you are a "deposit", you are confusing hydrogen bound in compounds with elemental hydrogen) and water that evaporates doesn't miraculously disappear from the Earth (this is mass conservation 101). The only way to make oceans a bit more shallow is by moving the water into ice on the polar caps, that's what have happened several times in the Earth history during glaciation periods (but never to the extent you are suggesting: "half of the deep", Google for "Doggerland", "Beringia" or "Bering land bridge").

 

[Conor Sullivan]

Yes, I did mention the rocks containing hydrogen, though that is a more aesthetic aspect to the story rather than the scientific foundation I am looking for. What I imagined was actually a gigantic hypothetical cavity in the Earth that held hydrogen gas, similar to the artificial subterranean salt caves that are used to store hydrogen gas.

Yes, I wasn't sure about the plausibility of such a great drop in ocean levels. In my mind I supposed the atmosphere would have taken so much damage as to allow the increasing heat to evaporate the water at great speed, and somehow allow it to escape the atmosphere. I am mostly thinking that if it is supposed that other planets in our solar system once were abundant with water, it would have to be similar to the onset of that process that affected those planets. A deteriorating atmosphere is my only guess, but I am completely open to any other theories as I don't think a mass freezing can apply to my story, at least in the simplicity I am trying to keep.

 

[Borek]

What I imagined was actually a gigantic hypothetical cavity in the Earth that held hydrogen gas, similar to the artificial subterranean salt caves that are used to store hydrogen gas.

And where does the hydrogen came from? And how did it survive OUR times, when we get to every end of the globe in a search of minerals that can be used for energy production?

A deteriorating atmosphere is my only guess

That's a process that takes much longer timescales than 100 ka.

 

[Conor Sullivan]

The particular spot in which this hydrogen deposit would be is under the current ocean floor somewhere around the Azores, which would be revealed by my hypothetical drop in ocean level. I think the idea is so far fetched that it is hypothetically possible given the array of information that we still cannot confirm regarding what lies beneath some places on the planet. Perhaps it is a deposit that accumulated over those 100000 years by means unknown to us now, but possibly produced by shifting plates or something of the sort.

I suppose I will have to do more research into another possible mass decline in water, as I can't stretch the time too much further as my story includes ancient ruins of modern ruins today, such as the base of the egyptian pyramids, weathered down to roughly 50 feet in height.

Thanks again!

 

[DaveC426913]

... the base of the egyptian pyramids, weathered down to roughly 50 feet in height.

Not sure how flexible your story is, but it is far more plausible that the pyramids would be buried in giant sand dunes than eroded.
Sand dunes tend to build up around stationary objects if not dug out.

 

[Conor Sullivan]

Interesting point. There are actually multiple relics in my story that are buried beneath sand but are revealed by a staff used to write sigils in the sand which arouses the essence of the gods (aliens) who react with a great earthquake and winds that stir up and move the sand from the area many feet deep. It's a flexible story haha. The weather pyramids are inhabited by another civilzation built upon the ruins, so many different factors could keep the ruins exposed. Thanks for the input; it keeps the ideas flowing.

 

[DaveC426913]

I think the question that needs to be asked is: how fast does your story need the ocean levels to rise? And by how much?

It is beyond plausibility for it to happen in anything but a very long timeline, as well as to raise the ocean levels by, say, half. We're talking about a volume of underground gas combining with atmosphere to the extent of volume of ocean.

It wouldn't be too hard to make a order-of-magnitude approximation of how much hydrogen and air would be to be consumed in order to produce that volume of water.

 

[Conor Sullivan]

In regards to the ocean rising, I would suggest that there were a huge volume of water within the ice caps, and as they gradually were to melt, the outer ice ring that held the water reservoir inside would thin, and then eventually break, releasing a titanic amount of water to cause a global flooding. As my story also involves the history of around 12000 years prior to now, and alludes to the great flood that ancient cultures speak of, the cause could be similar, but I feel it should connect with the global warming we are experiencing now. I wouldn't like to go as far as something as extravagant as a pole shift, but something more grandiose such as influence from alien lifeforms could possibly integrate into the story. Though, a giant water reservoir exploding from the currently melting ice caps is my current idea.

In regards to the hydrogen deposit, I know there is hydrogen gas in the Earth above or below oil deposits. I have to research how it develops there, but perhaps the heating planet could be a factor in more gas developing under the crust. A ridiculous amount, but an amount that must develop for the apocalyptic paradigm shift to occur.

The event of this fissure breaking open to spread rain across the planet is meant to be an event of great magnitude, turning the tides of human life, and the tiny act of opening this chest and lighting a spark is meant to show the interaction between the macrocosm and microcosm and how the two are completely intertwined, and how the single, man who lights the spark is the key factor in the destiny of the entire planet. It is meant to show the relevance of syncronicity in life and the great purpose of even one miniscule factor having the ability to cause great change. Hopefully to influence the reader to meditate on the power within every moment and every thought, no matter how irrelevant they may seem.

 

[Vanadium 50]

The oceans weigh 10^21 kg or so. That means you need 10^20 kg of hydrogen and 10^21 kg of oxygen. That's much less than the weight of the atmosphere, so there's not enough oxygen to do what you need. Also, that's a lot of hydrogen - at STP it would occupy a volume close to that of the earth.

 

[Conor Sullivan]

Is that the weight of the current ocean? In the story the oceans are at half of their depth, so to bring them back to the current height, I would only be looking at half. Even if there could be rain to cause them to rise a quarter of what they are today, that would be a reasonable amount to support the idea in the story that the Earth would be rejuvenated into turning a mostly barren planet back toward a mostly green and lively terrain.

 

[Vanadium 50]

I didn't worry about factors of 2. If you are off by thousands, it doesn't really matter if it's only 500. You have nowhere near enough oxygen in the atmosphere to make a dent in the oceans.

 

[willem2]

The weight of the oceans is 1.37 * 10^21 kg, and the weight of the atmosphere is 5.5*10^18 kg, with 21% oxygen. There is only about 0.08% of the oxygen that is needed.
There is probably enough water in the Earth's crust and mantle bound up in various minerals, so no need to burn hydrogen.
https://www.newscientist.com/article/dn25723-massive-ocean-discovered-towards-Earth's-core/
Good luck getting it out without killing us all.
Using up all of the oxygen in a short time won't be fun either. obligatory xkcd link: https://xkcd.com/809/

 

[Borek]

I don't see much sense in trying to get a particular detail right but ignoring the fact everything else is wrong.

 

[DaveC426913]

the Earth would be rejuvenated into turning a mostly barren planet back toward a mostly green and lively terrain.

I think you're going to run into a problem that, in order to produce the required amount of water - even with ideally-contrived circumstances - you will literally use up all the oxygen in the atmo, leaving just a poisonous nitrogen atmo.

 

[Borek]

leaving just a poisonous nitrogen atmo

Nothing poisonous about nitrogen, it is perfectly inert.

 

[DaveC426913]

Nothing poisonous about nitrogen, it is perfectly inert.

Better word is an asphyxiant. It will kill life (including humans) if breathed in too pure a form.

 

[Borek]

This is putting things on the head, it is not nitrogen that kills, but lack of oxygen. Replace nitrogen with hydrogen, helium, argon, or any other inert gas and the effect will be the same.

 

[DaveC426913]

This is putting things on the head, it is not nitrogen that kills, but lack of oxygen. Replace nitrogen with hydrogen, helium, argon, or any other inert gas and the effect will be the same.

You're bifurcating bunnies.
1] Pure nitrogen is an asphyxiant.
2] Nitrogen is not entirely inert in the physiology of metabolism, separate from a lack of oxygen.
3] To the context of the thread, an atmosphere drained of all its oxygen will kill air-breathing life.

 

[Bystander]

Might be useful to review cosmic abundances; there are far too many chemical consequences being/been asserted in this thread to merit any claim to a significant relationship to fantasy let alone physics.

 

[Khashishi]

For half the ocean to evaporate, the Earth would have to be pretty damned hot. Consider that the pressure of the atmosphere would be much higher than today's atmosphere, due to the copious amounts of water vapor in the air, which is nearly entirely water vapor at that point. Since the atmosphere is almost entirely water, there's very little difference between evaporation of water and boiling. Both would occur at nearly the same temperature. That temperature is quite high, due to the high pressure. For example, at 100 bar, the boiling point is around 300C. I'm not sure if the pressure or the temperature will kill you first.

Note that beyond the critical point (~376C) you can no longer distinguish liquid and gaseous water, and evaporation has no meaning.