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All of a sudden, overnight, abruptly, weather forecast guys go on strikes... everywhere is raining nitric acid non stop so that on average the amount reported is 100mm and the pH level is 3 occasionally fall to 1.5.

I believe that such a phenomenon would spell the end of humanity as we know it, all kind of infrastructures and buildings will be dissolved and the deadly miasma. Given such a scenario and modern technology what would be our best bet beside prayer?

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  • $\begingroup$ Nobody has any time to prepare? $\endgroup$ – Joe Bloggs Dec 27 '19 at 9:21
  • $\begingroup$ @JoeBloggs: at first it is an unusual occurrence then it gets bad by the days. $\endgroup$ – user6760 Dec 27 '19 at 9:27
  • $\begingroup$ A pH of 3 might be workable, a pH of 1,5 is too strong. We can't realistically cope with that. The difference between the two is quite big. $\endgroup$ – Mast Dec 27 '19 at 17:06
  • $\begingroup$ This is a Mass Extinction event. In the sea, everything which needs its shell dies in a few weeks at most, which cascades to many other problems. Everything on sea and land gets eye damage and skin damage, and no healing is possible with constant rain. Most animals and plants will die in the long term, and those that remain will be tolerant of their new nitric acid world. $\endgroup$ – Christopher Hostage Dec 27 '19 at 17:54
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    $\begingroup$ I am confused... is the weather forecaster strike somehow related to the acid rain? Or was that just there as flavor text? $\endgroup$ – SRM Dec 27 '19 at 18:53
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There is no hope. Emergency units which are trained and equipped to contain emergencies like this can cope with small scale incidents like a truck breaking open it's load of acid on the highway after a crash. An oil spillage from a tanker is already too big.

Worldwide acid rains means extinction: we don't have means to protect nor to sustain ourselves which are not dependent on the outside.

Large scale hydroponics is not yet up to speed for such a challenge, and even if it was there is no Teflon coated logistic available to distribute the food.

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    $\begingroup$ Upvoted. I was hoping for a miracle but now I will pray for the rain to stop. $\endgroup$ – user6760 Dec 27 '19 at 11:59
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    $\begingroup$ Yes even this relatively dilute acid would be deadly to most life on Earth. All human food stuffs would be killed off in days to weeks. It would only be survivable in an enclosed or protected environment such as a nuclear submarine or very dry deserts with water available from very deep wells. And these environments would not last in the longer term. $\endgroup$ – Slarty Dec 27 '19 at 13:52
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    $\begingroup$ @Slarty 1.5 pH would not normally be “relatively dilute”… $\endgroup$ – fectin Dec 27 '19 at 16:43
  • $\begingroup$ On top of that, coating everything with Teflon has its own problems. $\endgroup$ – Mast Dec 27 '19 at 17:08
  • $\begingroup$ pH 1.5 is only 0.2% HNO3 (by mass). It's more than "relatively" dilute, but still quite corrosive. $\endgroup$ – Alexander Dec 27 '19 at 17:29
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Acid nitric has pKa = -1.38 which is quite strong: it fully dilutes into water, it means it's also stronger than pure acid (H3O+) in water, and can interact react with compound that would not react in water diluted acid.

https://pubchem.ncbi.nlm.nih.gov/compound/Nitric-acid#section=Safety-and-Hazards

It is also used with sulfuric acid to create Aqua regia, very reactive and used to clean from noble metals, which are usually the most difficult to clean (ie., remove from the surface to clean).

https://en.wikipedia.org/wiki/Aqua_regia

It is however possible to have a protection from such rains (glass, teflon...), but most open sky exposed life would be eaten. If resistant shelters are built, spots of life (or as extended as the shelter !) would survive, including space life (space station(s)). I believe this would also involve air and water processing. One possible protection is a flowing layer of buffer solution with water, which will be resistant to acid change and protect the infrastructure from the acid rain. This would involve continuous processing of the buffer protection. The problem is that life needs the UV from the sun for plants to create sugar and energy available to life: humanity will need to find a way to have both protection from acid and let trough UVs for culture.

A more dangerous catastrophic event would be the stopping of the Earth's natural dynamo, which creates the magnetosphere, which protects life from solar rays, which are extremely mutative.

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Life on Earth would be severely damaged, but humans may survive

Nitric acid with pH of 1.5 corresponds to 0.2% solution. From chemical perspective, this is very dilute. This concentration lacks oxidizing power that allows the acid to eat through many materials, like in a dramatized "Alien" movie. Still, 1.5 is very acidic. Infamous "acid rains" have pH only in 4+ range.

If 100 mm precipitation is a one-time event, things will go to normal. Many roofs will leak, and many cars corrode, but it all could be rebuild and replaced. The effect on crops would be more damaging, but most of those 100 mm will run away from from the fields. Water ecosystems will be damaged the most, because many organisms would not be able to survive after this rainfall. Some will go extinct, but eventually life will rebound. People caught in the open will suffer from skin burns, and, without medical treatment, may die. Chemically, nitric acid will react with many minerals and soil ingredients, eventually bringing pH to normal levels.

If 100mm acid rains will repeat indefinitely, life on Earth as we know it is doomed. Land and oceans can absorb some acid, but eventually all chemical sinks will be filled, and environment would turn to very acidic. Few organisms can survive at pH as low as 3. However, those few acidophiles will flourish and eventually replace all other life forms on Earth. Life will go on.

Humans, however, will be brought to a brink of extinction. All our food base will be destroyed. We can't turn ourselves into acidophiles, and can't readily use acidophiles as food source. In a short term, humans would need to find sturdy shelters and secure as much food and equipment as possible.

What would be a secure shelter? As I mentioned before, 0.2% is a diluted acid. Most existing roofs can't cope that, but that's mostly because of the use of iron nails and inadequate sealing. Acrylic plastic and glass can tolerate diluted acid with no problem.

Humans can secure and acidproof existing greenhouses. This would give us some food, though it would be sufficient only for a fraction of today's population.

Cars and locomotives would be unsalvageable. But we can make our machinery more resistant to this acid. Popular materials like stainless steel and brass are reasonably resistant to diluted acids, and protective coating can further improve resistance.

Humans can go out in this rain, if wearing full protective clothing, and cleaning those clothing with alkaline water afterwards.

Fossil fuels can still be burned, solar panels would still work (with sufficient sealing). Hydro and wind turbines would be more challenging because of high corrosion.

Overall, if humans can do it right, they will survive, as a race.

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