I saw [this video](https://youtu.be/V4qzwykYuNw) the other day: how do they isolate each individual gas like that? Which also led to me wondering how do they isolate helium in such large volumes so it can be used in party supply stores for balloons?
I’ve tried to read about air separation on Wikipedia but I definitely need someone to please.
In: Chemistry
There are lots of different ways of doing this and it will depend on the gas you want to extract and the gasses you want to extract it from.
Generally, you exploit the fact that gases behave differently, both chemically and physically. You can exploit different condensation temperatures, you can exploit the fact that other chemicals might react with certain gasses over others, or that certain liquids or solids might absorb certain gasses over others.
Specifically for helium, you can lower the temperature of the gas. Helium has the lowest boiling point, so all other gasses will turn into liquid, leaving helium in a gaseous state. You can top that off by having an absorbent material such as activated charcoal, which will absorb other gases, leaving you with almost pure helium.
For almost all common gases, you distill them, just like making liquor or gasoline but much colder. Cool the mix down until all components are liquid, then gradually heat it up: the one with the lowest boiling point boils off first, then the second, etc.
Just like alcohol or gasoline, you don’t get 100% separation from one boil-off stage, you have to do multiple cycles.
Helium in particular is a byproduct of natural gas production. Radioactive decay in rocks releases alpha particles (He nuclei) which accumulate in some of the same underground reservoirs that natural gas does. Liquefy the natural gas and the helium remains.
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