--- Log opened Sat Sep 24 00:00:28 2022
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09:17 < fenn> https://ichorlifesciences.com/about/ a heartwarming story of a generic garage biotech startup
09:26 < muurkha> dedicated to replicating the immortal blood of the Olympians?
09:28 < fenn> iirc it was a beverage
09:28 < muurkha> hahaha
09:29 < muurkha> "what would you do if you had the blood of the gods in your hand?" "dude, I'd drink that shit"
09:30 < fenn> obvs
09:51 < kanzure> you wouldn't?
09:57 < docl> well it might be full of antimatter or something
09:57 < docl> but it's gotta be like a 50/50 shot at immortality
10:02 < muurkha> maybe inject it into a rabbit first
10:06 < docl> hmm. say you have a cnt fiber threaded through a bunch of rings. those would be rich in rotational microstates
10:08 < docl> you could then use a magnetic field to confine them to fewer plausible microstates
10:11 < docl> pressure causing them to rotate closer together would also work
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11:55 < docl> phase changes make more sense to me now. e.g. when water freezes, the hydrogen bonds go from many probable-enough-to-count bonds to a much smaller set of basically certain bonds, which implies fewer possible-enough-to-count values for their relative positions and velocities
12:01 < docl> I'm now thinking simple diamond deformation as an effective entropy sink is unlikely, as long as the bonds are strong enough to retain the tetrahedral alignments high certainty. you kind of need weaker bonds to not narrow the possibility space. or strong bonds in conflict. a needle grabbing a carbon atom from a diamond surface would have a high entropy phase where the carbon wants to adhere to the 
12:01 < docl> needle and the diamond with equal probability
12:03 < docl> and the fact that it happens in such a small space tends to limit the entropy further
12:04 < docl> which is kind of the point, if you want to move atoms around in precise ways you need to bottleneck the number of probable states
12:13 < muurkha> :)
12:13 < docl> an atomic structure seems to open plausible states that a hot ideal gas doesn't have though, like a rotating ring balanced by tensile forces of bonds, a coiled spring in various states of compression, a fiber bent some amount along some set of plausible vectors
12:18 < docl> question is how to get entropy bottlenecks that reversibly convert to major entropy sinks with ratios equivalent to huge amounts of gas expansion without changing the actual volume much
12:20 < muurkha> well, the traditional way, as you sort of mentioned, is phase changes
12:20 < docl> definitely looked into that :)
12:21 < muurkha> the hydrated Glauber's-salt/table-salt eutectic has a melting point that is convenient for many such applications involving humans
12:21 < docl> water is pretty good, it's just not going to get us to tens of MJ/kg
12:22 < docl> I worked out that CaCl hydration to hexahydrate is about 10x as much as water
12:22 < muurkha> really?
12:22 < muurkha> I mean I know it's pretty big but I didn't realize it was that big
12:24 < muurkha> how do you figure?
12:24 < docl> .tw 1569125326890102784
12:24 < saxo> @br___ian Calcium chloride seems promising. Easy to get at the store. You'd need to be careful no metal comes into contact if you want it to last. It's liquid in the hexahydrate form. 100 grams is roughly 2600 kJ cooling, more than evaporating a kilogram of water // https://en.wikipedia.org/wiki/Calcium_chloride (@lsparrish, in reply to tw:1569123958724923392)
12:24 < docl> was brainstorming wearable cooler ideas
12:25 < docl> I should recheck the math of course
12:25 < muurkha> no metal except silver
12:27 < docl> I was looking at the standard enthalpy of hydration, -2608.01kJ/mol
12:27 < muurkha> I think you get 1812.59 kJ/mol for the enthalpy of formation from the anhydrous form to the hexahydrate
12:28 < muurkha> 2608.01 kJ/mol is the enthalpy of formation of the whole hydrated compound, including what you get from combining the calcium and the chlorine in the first place
12:28 < muurkha> the anhydrous muriate is 110.98 g/mol
12:29 < docl> ahh, so you have to subtract the anhydrous number since you aren't electrolyzing
12:29 < muurkha> I think that's right
12:29 < docl> and it's 6 molecules of water per pair of ions
12:30 < docl> so maybe a lot less impressive than I was thinking 
12:30 < muurkha> oh hmm, I wonder if I was calculating that wrong all along
12:30 < muurkha> I wasn't thinking it included the enthalpy of the water itself, does it?
12:31 < docl> well the hexahydrate means including the water, I think
12:32 < muurkha> I mean, does it include the enthalpy from burning hydrogen to get water?
12:32 < muurkha> water's standard enthalpy of formation is -285kJ/mol
12:32 < muurkha> well, -286
12:33 < docl> I think it's just the comparatively weak hydrogen bonds involved in this
12:33 < muurkha> which would work out to 1716 kJ for a mole of hexahydrate
12:33 < muurkha> which is suspiciously close to the 1812.59 number I came up with
12:33 < docl> well now that you mention it I could be wrong :)
12:34 < muurkha> people do sometimes get thermal burns from putting anhydrous muriate of lime in their mouths
12:36 < muurkha> but some of that heat is also from the exothermic dilution of the already-dissolved solution
12:37 < muurkha> I think?  https://web.archive.org/web/20090917163015/http://www.dow.com/productsafety/finder/cacl_2.htm is Wikipedia's reference for this
12:37 < muurkha> I feel like this ought to be amenable to kitchen experiments
12:37 < docl> hmm. adding an acid or base to water does yank hydrogens away, hence the OH- and H+ ions
12:39 < muurkha> I think this probably has to be including the heat from burning the hydrogen
12:41 < muurkha> just because 16 MJ/kg is not just more than evaporating water, it's more than burning nitromethane
12:41 < muurkha> even if we aren't equipped to determine the heat produced by hydrating the anhydrate to six significant figures (or, perhaps more easily, the tetrahydrate) we still ought to be able to distinguish between 16 J/g and 1 J/g
12:45 < docl> .wik Hydrogen_bond
12:45 < saxo> "In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative 'donor' atom or group (Dn), and another electronegative atom bearing a lone pair of electrons—the [...]" - https://en.wikipedia.org/wiki/Hydrogen_bond
12:45 < muurkha> my notes on this, based on the evidently erroneous idea that these numbers included only the heat from hydrating the salt, are at https://derctuo.github.io/notes/muriate-thermal-mass.html
12:45 < docl> Hydrogen bonds can vary in strength from weak (1–2 kJ/mol) to strong (161.5 kJ/mol in the bifluoride ion, HF−2)
12:46 < muurkha> oh, no, actually I see I did it correctly?
12:46 < docl> so probably 12-24 kJ/mol for a hexahydrate
12:46 < muurkha> > The anhydrous salt’s standard enthalpy of formation is -795.42 kJ/mol, compared to -1403.98 kJ/mol for the dihydrate and -2608.01 kJ/mol for the hexahydrate. However, presumably much of that is already in the water, whose standard enthalpy of formation is -285.83 kJ/mol; six times that is -1715 kJ/mol, leaving only -97 kJ/mol from adding water to the anhydrous form (- 2608.01 795.42 (* 6 
12:47 < muurkha> 285.83)) = 97; from the hexahydrate to the dihydrate we have (- 2608.01 1403.98 (* 4 285.83)) = 60 kJ/mol. The molar mass of the anhydrous muriate is 110.98 g/mol, and of the water is 18.015 g/mol, so this is 147.01 g/mol for the dihydrate or 219.07 g/mol for the hexahydrate; in theory, then, we can produce 408 kJ per kg of the dihydrate by hydrating it to the hexahydrate, whose heat capacity is 
12:47 < muurkha> 300.7 J/mol/K; this works out to a temperature rise, theoretically, of 199.5°. (The heat of dissolution of the hexahydrate I do not know.) This 408 kJ/kg compares very favorably to 251.2 kJ/kg for the salt of Glauber.
12:55 < docl> I was picturing hydration of a salt as working similar to phase change in water, so if you have liquid water bonding to a salt it's going to release similar heat per kg of water as forming ice. maybe more or less depending what it does to the ions though
12:57 < docl> weakening a bond increases the number of microstates so my newfound entropy understanding says there's more to it
13:09 < docl> hmm, NaCl wants to form nice hard cubic shapes because that's the most stable arrangement. you could put anhydrous NaCl inside a small spherical container under pressure to force it spherical. if the sphere were perfect, the number of equally probable cubes would be infinite. would that make a strong entropy sink?
13:10 < docl> the volume of the sphere could be equal to that of the cube that would form
13:12 < docl> increasing the stretchiness of the sphere would allow the salt to organize, thereby decreasing its entropy and emitting heat. returning it to original volume would force the salt to disorganize and absorb heat
13:15 < muurkha> salt doesn't exert much force when it crystallizes
13:18 < docl> I'm not sure if that is an advantage or disadvantage, given less intense bonds are more entropy rich
13:22 < docl> hmm. if you have a diamond crystal on the scale where the bonds lengths matter a lot to the structure, forcing it to occupy a spherical container would seem to make all possible tetrahedrons equally probable
13:23 < docl> .wik Nanodiamond
13:23 < saxo> "Nanodiamonds, or diamond nanoparticles, are diamonds with a size below 1 micrometre. They can be produced by impact events such as an explosion or meteoritic impacts." - https://en.wikipedia.org/wiki/Nanodiamond
13:27 < docl> huh, they apparently naturally tend to be spherical or elliptical with all kinds of impurities and stuff at the surface
13:28 < docl> even with high purity environment, if it can stabilize as graphite, that's probably no good
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--- Log closed Sun Sep 25 00:00:29 2022