Gold isn’t inert, it just has bodyguards protecting it
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Interesting read!
Never thought I'd come across the topic of gold nano particle catalysts after writing my bachelor's about trying to use them for making renewable plastics from sugar* and then making the switch to IT, but this was a nice throwback.
*Not that anything came of it. But I can still claim to have used up multiple grams of highly purified gold for my bachelor's. Having a catalyst and having a stable catalyst are two very different things!
Never thought I'd come across the topic of gold nano particle catalysts after writing my bachelor's about trying to use them for making renewable plastics from sugar* and then making the switch to IT, but this was a nice throwback.
*Not that anything came of it. But I can still claim to have used up multiple grams of highly purified gold for my bachelor's. Having a catalyst and having a stable catalyst are two very different things!
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So while there's potential in the metal here, platinum remains the gold standard for catalysts is what I'm reading.
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So, not so much bodyguards, more a peloton or a phalanx. Gold is just very egalitarian I guess.
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I thought the factoid was that all of the gold extracted by humanity would fit in a couple of Olympic swimming pools?
Now, if you're including all of the overburden and gangue moved to extract that gold, then I can believe you're talking multiple mountains' worth
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My chemistry topped out before encountering gold nanoparticles, and a quick side trip has now made me aware of gold nanourchins, too. A nice way to start a typical June Gloom Tuesday--thanks!
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Albino_Boo
Ars Tribunus Angusticlavius
There's roughly 3500 tons of gold mined every year. The total amount of gold mined is estimated to be 220,000 tons. There's some big error bars on that figure
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I'm not sure that's true. There's plenty of gold in the earth, sure. But it's in the mantle. Gold's use in industry is limited by actual scarcity, compared to iron, aluminum, nickel, cobalt, even titanium. It's true there'd be more in circulation if we melted down all the gold bars, but it still wouldn't be economical, or even possible, to start ripping out all the copper (probably the closest functional analogue) and replacing it with gold.
There are places where things would be "better" with gold, I'm sure, but if we can satisfy 99.999% of that need with the vastly cheaper and more available copper, why wouldn't we? If we're really worried about oxidation, we can gold-plate, which we do already. (Keep in mind, there are scenarios in which we don't even use copper - high tension wires are aluminum, due to weight and cost of copper.)
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Made me curious, found https://www.usgs.gov/faqs/how-much-gold-has-been-found-world (may be about a decade old) which says a cube 23m on a side, so about 5x https://en.wikipedia.org/wiki/Olympic-size_swimming_pool
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Globally we mine roughly 100-200 m^3 of gold per year -- an olympic-sized swimming pool every couple decades. We've been at that rate for a century or so, which means more like 5-10 swimming pools, which is indeed still not a mountain.
Edit: my estimate was clearly the slowest to come up with. Nice to see we all ended up in the same place though.
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Not in my wheelhouse but I am guessing a couple orders of magnitude more iron than gold has been purified.
Very interesting article. Thank you Chris.
Very interesting article. Thank you Chris.
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One of my friends in college did her senior project on gold nanoparticles, and she described gold as being kind of fuzzy/goopy: If you take an individual gold atom, it likes to surround itself with lots of bonds which have high degeneracy (have equal-ish bond energy) which means that they can move around, making the nanoparticles good for transporting other things. It's also big, so if the surrounding structure is made of lower-atomic-number stuff, it can form a fairly large "cage" around itself that has fairly tunable properties (which is largely why it's used for so many things).
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So would this be a good model/analogy for how catalysis works? What I'm interpreting the description of catalysis to mean is that:
* Without a catalyst, all the atoms have to react with to break apart, is other of the same type of atom. So to get them to split, you have to heat them up quite hot so they have significant chance of smashing into each other at high enough energy to break apart. So, you could think of pure O2 gas, you heat it up very hot, and it becomes at a high enough temperature, statistically likely that 2 O2 atoms will hit each other hard enough to break apart into 4 x O1, and as long at the gas stays hot, they are unlikely to join back up into O2. If you have something else in your reaction chamber that you want it to react with, the free oxygen molecules are now available to react with that other material.
* But in catalysis, it's like you now have the ability to hold onto one of the atoms in the molecule and "pull it apart", and when doing this, you don't need as much energy, because you only need the minimum amount of energy needed to break the bond,, because when you heat up a material, you get multiple different types of motion, and not a lot of wasted extra energy that's required to heat up the gas to the point where the smashing is likely?
Back to the point of different types of motion - heat can increase translational motion (that is, molecules travelling in a straight line in space until they hit something else), rotational motions (the molecule can spin freely like a baseball), and molecular vibrational energy - that is, the atoms bonded together in a molecules aren't really "fixed" and at rest with respect to each other, if I recall high school chem correctly - they sort of vibrate with respect to each other like two masses attached to two ends of a common spring (although molecules can of course have many more than 2 atoms, and I think can even form more than a single bond - e.g. you can get triangle looking bonds where atom 1 bonds to atom 2 and 3, and atom 2 and 3 each bond to each other and atom 1 like:
1
/ \
2--3
And many more complex arangements like hexagon 'rings', cubic lattices, etc (as discussed in the article).
So, if one of those atoms attached to a catalyst, then you can sort of "hold the molecule still" and heat energy will increase vibration but be unable to increase translation or rotation?
Or, maybe thinking about this more precisely, aa you heat up the whole reaction chamber, what's really happening is external "free moleucles" (e.g. neighboring O2) molecules are smashing into the 'held' O2 molecule, and there's an increased chance when one of those "free molecules" hits the free end of the O2, that free end breaks off the other? Or if it doesn't break off, it does increase vibrational energy, and maybe the next molecule to smash into it breaks it off because the increased vibration makes it more likely the next or third or fourth time another molecule hits it?
Update: Question - if catalysis requires one end to get stuck to the surface of the catalyst, how do you get that now stuck on atom to release?
I guess maybe after you have consumed the other atoms released by the catalysis, you heat up the catalyst a little bit more and the increased temperature forces the stuck on atom to get ejected off the surface?
Then you can cool down the catalyst and start again on the next cycle?
* Without a catalyst, all the atoms have to react with to break apart, is other of the same type of atom. So to get them to split, you have to heat them up quite hot so they have significant chance of smashing into each other at high enough energy to break apart. So, you could think of pure O2 gas, you heat it up very hot, and it becomes at a high enough temperature, statistically likely that 2 O2 atoms will hit each other hard enough to break apart into 4 x O1, and as long at the gas stays hot, they are unlikely to join back up into O2. If you have something else in your reaction chamber that you want it to react with, the free oxygen molecules are now available to react with that other material.
* But in catalysis, it's like you now have the ability to hold onto one of the atoms in the molecule and "pull it apart", and when doing this, you don't need as much energy, because you only need the minimum amount of energy needed to break the bond,, because when you heat up a material, you get multiple different types of motion, and not a lot of wasted extra energy that's required to heat up the gas to the point where the smashing is likely?
Back to the point of different types of motion - heat can increase translational motion (that is, molecules travelling in a straight line in space until they hit something else), rotational motions (the molecule can spin freely like a baseball), and molecular vibrational energy - that is, the atoms bonded together in a molecules aren't really "fixed" and at rest with respect to each other, if I recall high school chem correctly - they sort of vibrate with respect to each other like two masses attached to two ends of a common spring (although molecules can of course have many more than 2 atoms, and I think can even form more than a single bond - e.g. you can get triangle looking bonds where atom 1 bonds to atom 2 and 3, and atom 2 and 3 each bond to each other and atom 1 like:
1
/ \
2--3
And many more complex arangements like hexagon 'rings', cubic lattices, etc (as discussed in the article).
So, if one of those atoms attached to a catalyst, then you can sort of "hold the molecule still" and heat energy will increase vibration but be unable to increase translation or rotation?
Or, maybe thinking about this more precisely, aa you heat up the whole reaction chamber, what's really happening is external "free moleucles" (e.g. neighboring O2) molecules are smashing into the 'held' O2 molecule, and there's an increased chance when one of those "free molecules" hits the free end of the O2, that free end breaks off the other? Or if it doesn't break off, it does increase vibrational energy, and maybe the next molecule to smash into it breaks it off because the increased vibration makes it more likely the next or third or fourth time another molecule hits it?
Update: Question - if catalysis requires one end to get stuck to the surface of the catalyst, how do you get that now stuck on atom to release?
I guess maybe after you have consumed the other atoms released by the catalysis, you heat up the catalyst a little bit more and the increased temperature forces the stuck on atom to get ejected off the surface?
Then you can cool down the catalyst and start again on the next cycle?
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Six orders of magnitude, I’d have thought: the world produces about two billion tons of steel a year and about four thousand tons of gold.
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1. The total amount of gold mined throughout human history probably wouldn’t take up more volume than a mid-to-large urban building.
2. It’s rarity, general absence of catalysis, and resistance to oxidation is the whole reason it has been used as the most esteemed store of value and medium of exchange by every society that had access to it with any degree of commercial activity or state-driven exchange as far back as can be discerned.
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Thanks. Still seems quite a bit when you consider that main sequence stars end product is almost all iron and gold is only created in very high energy stellar events like kilonova or supernova.
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Albino_Boo
Ars Tribunus Angusticlavius
The majority of Iron comes from a Type Ia supernova, roughly half solar mass per supernova.
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I'll just keep stacking gold, silver, and platinum. Sovereign coins over bars though for gold.
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Yet from a quick search, platinum is roughly 30 times rarer than gold, as well as being used for jewelry also. So maybe there is a place for gold nanoparticle catalysts - as long as you can keep them from getting lost.
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It's always funny that people perceive gold to be "inert". While it doesn't oxidize, it will very happily form compounds with many things at any sense of elevated temperature.
I've been banging my head for the past two months to slow down formation of gold-chloride and gold-silicide, ruining our gold thin films. Time for more deposition runs (sigh...).
I've been banging my head for the past two months to slow down formation of gold-chloride and gold-silicide, ruining our gold thin films. Time for more deposition runs (sigh...).
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Their order of magnitude guess was at least right to within an order of magnitude...
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My understanding is that specifically the cost of extraction is why it's been consistently used that way. That it's mostly non-reactive, and kinda pretty, are nice bonuses, but the principle thing is that it took (and still takes) a lot of work (mostly labor, but also capital) to mine and refine gold. In the realm of, like, a month's work per ounce.
This crazy-high cost:weight ratio means it's great for storing value (you can fit years of work into a small chest), making high-value transactions (you can carry enough material to pay for months of work in a small pouch), and advertising wealth (you can demonstrate wealth and power by wearing a few years' worth of labor as simple jewelry). Its non-reactivity is useful (although not decisive - silver often fills a similar role despite tarnishing), but its weight and malleability are net drawbacks I think. It's the fact that it has a robust value floor in terms of production cost that's the real upside.
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Fascinating story and conversation! I want to go deeper into this. There are quantum fields involved-the orbital shell is a useful analogy for organizing interactive experiment but the origin of gold may tell us more about the quantum nature of the material?
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I just read somewhere that all the gold and platinum is actually formed in neutron star mergers only.
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This is a nitpick, but gold is actually FCC - face centred cubic - which means that the basic crystal structure is a cube in which each face consists of 5 gold atoms forming a square with one atom at the centre surrounded by four others at the corners. Because all of the atoms except the central one are shared with other cubes, the actual number of gold atoms in what is called the unit cell is 4.
Look at the corner of a cube and there is a kind of wrinkled hexagon visible in the middle, with the three edges from the corner meeting six edges. This is where the hexagon originates. It is not a true hexagon face; you cannot actually cut through the crystal at a particular angle and get flat hexagons, whereas if you cut through the faces of the cube, you get a flat repeating pattern of interlocked squares.
The other form of close packing is hexagonal close packing, and this can have a face of flat hexagons exposed.
However, gold does not switch between the two.
Look at the corner of a cube and there is a kind of wrinkled hexagon visible in the middle, with the three edges from the corner meeting six edges. This is where the hexagon originates. It is not a true hexagon face; you cannot actually cut through the crystal at a particular angle and get flat hexagons, whereas if you cut through the faces of the cube, you get a flat repeating pattern of interlocked squares.
The other form of close packing is hexagonal close packing, and this can have a face of flat hexagons exposed.
However, gold does not switch between the two.
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You mean there's a kind of merger that adds rather than subtracts value?
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As someone who once had a small but very heavy bottle of gold cyanide in the lab safe, I concur.
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Albino_Boo
Ars Tribunus Angusticlavius
It starts out as Nickel 56, decays into Cobalt-56, which in turn decays into the stable Iron 56.
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Chris, good to see a new article from you. I've missed your humor.
Looking forward to your next laser article....
Looking forward to your next laser article....
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