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I have been trying to find a solvent for my fluorine-based cells. I have asked if CF4 could be an alternative to water, but I am sure I can find a better replacement. Is there any liquid at temperatures of -180 C to -170 C that has similar solvent properties to water?

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  • $\begingroup$ Does the solvent itself have to contain fluorine? There could be some non-fluorine based candidates that would still support complex fluorine chemistry and have a suitable temperature range. $\endgroup$ May 23 at 23:26
  • $\begingroup$ As long as it doesn't react with fluorine, I don't care. $\endgroup$
    – KaffeeByte
    May 24 at 0:07
  • $\begingroup$ I don't suppose going to -190 and using liquid fluorine itself is an option? You'd still end up with plenty in the atmosphere.. $\endgroup$ May 24 at 4:06

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The challenge is: a polar solvent like water, made of molecules that are not too esoteric, liquid at the prescribed temperature, and I am going to assume 1 bar pressure.

Ozone

ozone molecule

  • Melting point −192.2 °C; −313.9 °F; 81.0 K
  • Boiling point −112 °C; −170 °F; 161 K
  • Solubility in water 1.05 g L−1 (at 0 °C)

Ozone fits the bill. In our warm world it is transiently stable as a gas but tends to break down and react with reduced carbon and whatever else. In this cold world it will be a polar liquid - still comparably reactive but chemistry is sluggish at these temperatures and spontaneous reactions are rare.

Your cells will generate ozone liquid using electrochemistry. A world this cold will probably be dark but electricity will conduct well and I imagine the autotrophic organisms to be electrotrophs, harvesting ambient charge.

As plants use photochemistry to split the oxygen off of water, liberating O2 and keeping the hydrogen molecules, your autotrophs will use electrochemistry to generate ozone from liquid oxygen. Alternatively they might split the O off of water ice and combine that with O2 to form their ozone, liberating the hydrogen waste product.

In addition to being a polar liquid medium the ozone is good energy storage, always ready to energetically convert ambient hydrogen or methane back to water.

Your polar ozone blood can contain non polar micelles of liquid nitrogen, oxygen and argon just as our cells fill of water separate compartments with non polar micelles of lipid.


from comments /The only problem i see is the instability of ozone, in the most stable laboratory conditions it can only last just over a day before decaying into O2,/ @KaffeeByte

That is true at standard temperature. But the colder the ozone is the longer it lasts.

ozone decompostion

https://www.lenntech.com/library/ozone/decomposition/ozone-decomposition.htm

This world is substantially colder than -50 °C.

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  • $\begingroup$ The only problem i see is the instability of ozone, in the most stable laboratory conditions it can only last just over a day before decaying into O2, and this time is shortened the more unstable it's environment is. In the conditions of a home, its half-life is only minutes. $\endgroup$
    – KaffeeByte
    May 24 at 0:24
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Oxygen Difluoride?

Melting point -223°C, boiling point -144°C, and apparently already used as a solvent in one sci fi story called Camelot 30K (so sayeth wikipedia).

This is what you'll probably end up with at least as a byproduct if you have ozone and fluorine around as ozone decomposes catalytically in the presence of fluorine.

It has full p shells for all 3 atoms so I would expect it'd be more stable than ozone re: self disproportionation but it is definitely far more reactive towards anything vaguely oxidisable present.

The wiki page on oxygen fluorides notes that, a little like water, there are isolatable less stable analogues with more atoms such as O2F2 ('FOOF'), O3F2, etc.

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  • $\begingroup$ Okay, but is there any evidence that OF2 is a solvent? And also, where does it say that ozone decomposes catalytically in the presence of fluorine? I can't find anything that says that. $\endgroup$
    – KaffeeByte
    May 24 at 18:11
  • $\begingroup$ Probably very little direct evidence as it's exotic and toxic and fluorinated, but you'd expect it to be a mildly polar solvent. Ozone gets degraded catalytically by any halogen radical species which is why CFCs kill it. With CFCs we only consider Cl radicals as CF bonds don't break under those conditions but in an Fl atmosphere it'll be a thing especially if theres UV. TBH your far bigger problem is that ozone disproportionates like crazy; 2 O3 -> 3O2 is always thermodynamically favourable. Possibly worth borrowing Camelot 30K from a library and seeing if it addresses the chemistry in detail. $\endgroup$ May 25 at 0:52

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