Scrap Science - 2023-02-06
Having made some serious progress on our series of molten salt electrolysis experiments (successfully isolating aluminium, sodium, and lithium in other videos), we make an attempt at a particularly tricky metal to extract - calcium. You can find the other videos in this series here: Making aluminium: https://youtu.be/aSx59lbc5cg Making sodium: https://youtu.be/wb65RZh1ptU Making lithium: https://youtu.be/cIII542y0C8 Making boron (unsuccessfully): https://youtu.be/mmlAPF6PyQY In the video, I also refer to the following video by Cody'sLab, in which he extracts calcium metal from bones: https://youtu.be/B6zunpJ_Q9M
In 1967 I made lithium metal by electrolysing a solution of anhydrous lithium chloride in absolute alcohol. I can't remember the details, but I think I used frosted glass that I had made conductive with a graphite coating for one of the electrodes.
Cool! Can you remember how you applied the coating?
@@thomasklevgard I believe that I just rubbed a pencil over it. If I were to do it again then I might spray the surface with Nickel from an aerosol can.
How would you stop the lithium from reacting with the ethanol?
@@hantrio4327 The reaction, if it occurs is slow. Additionally, I suppose that you could cool the solution. But of course you would need to see a solubility curve.
Always hyped for a new Scrap Science video!!
This was cool, makes me want to buy a small furnace! I wonder if you could reach a saturated molten solution so that your new calcium can't dissolve any more?
I have absolutely no clue about how the dissolution of metals in molten salts actually works, so don't take what I say next to be the absolute truth.
From what I've heard, it generally seems like increasing the concentration of dissolved metal in a melt actually makes the mass conductive to electrons before the metal can 'precipitate from solution'. In these cases, you just end up shorting out the cell (preventing electrolysis) instead of getting metallic product. This is what stops you from being able to generate potassium from KOH (or even sodium from NaOH if your temperature is too high).
For calcium dissolution specifically, some state (quite convincingly) that the metal dissolves via a comproportionation reaction to form calcium(I) chloride. This is pretty interesting in its own right, but it makes it impossible to form the metal by reaching a saturated solution, since the metal is no longer in the zero oxidation state.
Anyway, glad you enjoyed!
Great work. Always happy to see next episode of molten salt electrolysis
I absolutely love your videos ❤ Please don't stop making them!! I would bet money on the fact that your channel is going to have a huge fan base in the future!!!
Great video as always
and its never too early to do more molten salt electrolysis!!
I hope you revisit this.
I've been wanting to make some Ca out of spite and have recently been digging through an old German metallurgy textbook from the 80s. (Metallhüttenkunde by Franz Pawlek)
I think the problem you had was localized heating surrounding the cathode due to current density. The way they used to do it was to use a large diameter water cooled iron cathode that would just touch the surface and them be slowly pullet out, allowing a slug of Ca to grow on the bottom as it's pulled out. The salt would freeze and the crust protects the metal.
I suspect that all Ca went straight into solution and the precipitated once it got away from the hot zone surrounding the cathode. I wonder if you cold make a solution of Ca/CaCl2 and then crash out the metal on some kind of cold finger between the electrodes...
One Alternative mentioned in the book is to use copper which forms a low (600°C) melting eutectic with Ca which would pool on the cell bottom for separation with vacuum distillation. I guess this would be similar to your Tin based approach.
Actually now I wonder if you could do this with MgCl2 and aluminum to make magnalium directly (Mg can "easily" be distilled off if desired). Based on the densities, the alloy might even float to the surface once it reaches a certain concentration.
Given Davy's description, I wonder if you could- NOPE, can't replace mercury with gallium, almost no solubility. I wonder if some of the other low melting alloys might work.
Nice to see your experimental skills - keep going & sharing, please.
Cool! It was just yesterday i was experimenting with my TIG welder, to melt a few small beads of calcium into one big one. And it went pretty well! Argon shield is working nicely=)
Great job, as always man!
i undertsand yhat its more difficult, but if you want to get calcium(and chlorine) and for example NaF\KF you can use complicated melt with CaF2+NaCl+KCl, i heard that its used in factory production as way of getting a lot of useful compounds
You know your stuff!
Yes, this is one of the only melts (along with a few other eutectic mixtures involving fluoride) which can successfully generate calcium without running into metal solubility problems. Generally, they're used to electro-refine calcium instead of electrowinning the metal directly (i.e. a calcium alloy is used as an anode, and the metal is 'electroplated' from the anode onto the cathode) - I assume this is because the loss of chloride over time may lead to reduced efficiency if one were to use an inert anode.
Regardless, as much as I would have liked to try a mixture like this, fluorides are tricky to get hold of (at least when they're not in the form of impure rocks), and making mixtures where you might generate soluble fluoride compounds makes me rather nervous anyway.
Nice explanation.
Good job!
I'm also thinking about preparation of calcium and sodium metal from molten chlorides for a long long time but I don't have complete setup yet. I'll try it soon :)
great vid keep up the great work
This is very informative video 🎉
very interesting i knew nothing about it..thank you..
Is it possible to make metallic iron by electrolysis of its salts rather than reduction of its oxides with carbon?
Any ideas about Calcium Oxide or Hydroxide as a precursor? I'm guessing the carbonate and sulfate are similarly insoluble in the ionic melt, as in water?
I once read somewhere that in order to produce calcium with electrolysis you have to strart with a mixture of 50% CaCl2 and 50% NaCl (in moles), which should melt at 300 °C. During electrolysis at the cathode only Ca2+ will get reduced (which at the time sounded weird to me, since Na has a slightly higher reduction potential, something like -2,71 V for Na/Na+ VS -2,76 V for Ca/Ca2+, maybe it's an overpotential issue...). Whether Calcium would get dissolved back in the NaCl/CaCl2 mixture I have no idea.
What you've described is actually the process for making sodium metal. In a mixture of NaCl and CaCl2, sodium is the one that gets reduced first. This is basically the only commercial process of making sodium metal that is economically competitive.
Additionally, standard reduction potentials pretty much go out the window here, since we're no longer working in aqueous conditions or 25 C. They're not particularly useful for making these kinds of predictions. At these temperatures, calcium is one of the most difficult metals to reduce, hence why we can't generally use eutectic mixtures.
I saw another commenter bring up using an alkali chloride eutectic mix to bring down the melting point, but given your results in this video, what about a eutectic with calcium carbonate? I found a paper says the melt temp gets down to 630 C with a 2:1 ratio of CaCl2:CaCO3. Might be able to drive that lower by adding some calcium hydroxide as well. Would love to see a part 2 to see if that's viable.
Very interesting!
This is definitely worth a go if I revisit this.
My only worry is that I've run into some issues in the past with using temperatures below the melting point of the metal we're making. Quite recently I tried making magnesium metal (which will eventually end up in a video) but obtained a terrible dendritic and reactive end product which didn't look like metal at all. I might be interested to see if calcium does the same thing when making it at temperatures below its melting point.
@@ScrapScience If you want a real rabbit hole that solves the issue of dendrite growth in electrodeposited metals, look into DC offset AC electrodeposition, also known as pulsed-current electrodeposition with deplating pulses. IIRC, ideal frequencies are in the kHz range, like a sine or square wave shifted up (or down, depending on how you measure) from the zero axis.
Does it emitt xrays?
Surely if you setup a slow purge of Argon into the top of your graphite crucible this would create a micro inert atmosphere inside the crucible and on top of the molten calcium chloride?
This is a little more tricky than it seems, since the cell itself is also generating chlorine/oxygen gas from the anode. Others have found that generally, the resulting turbulence introduced by a constant flow of argon actually does more harm than good, since it encourages the more reactive gasses to move around and react with our metal product.
With that said, if we could put our cathode in a protective tube (i.e. alumina or something), we could probably set up a flow of argon that would be isolated from the gaseous anode products. I've got some plans to hopefully implement something like this in future experiments... eventually.
Great video. I have to ask, though... why not calcium hydroxide? In another video, you used molten sodium hydroxide with a current in a similar way to obtain sodium metal. Could you not perform the same with calcium hydroxide, or is there some reason why this would not work? Would it just form calcium oxide instead?
Sadly, calcium hydroxide does decompose before it melts - turning into calcium oxide as you've guessed. Since our salt needs to be molten for the electrolysis to work, we'd require temperatures of over 2600 C to actually liquefy the oxide. It's just a whole lot easier to melt calcium chloride.
Are there any electronics at the bottom that would prevent the furnace from becoming a tube furnace by drilling a hole in the bottom and using it sideways?
All of the main electronics are underneath the main part of the furnace. So no, this wouldn't work directly. However, the actual heating part of the furnace seems rather isolated from the box of electronics beneath it, so I suppose the heating element and insulation could be separated and used for a tube furnace if desired (?).
Speaking from ignorance, is an inert environment really that difficult to cobble? Isn't it just a matter of putting everything in a box and supplying the box with N2 gas from a cylinder or a dish of LN2 left to evaporate? This was a great vid and I'm impressed with your success!
For many reactions, your suggestion would work perfectly. However, for these particular molten salt electrolysis processes, there are a couple of issues that make an inert atmosphere much more difficult.
The main trouble is that the reaction itself generates reactive gasses on the anode. We're generating a lot of chlorine and/or oxygen right next to our metallic product, so we'd be completely ruining whatever inert atmosphere we were trying to implement. To use an inert atmosphere properly, we'd need to cover the cathode and our reactive metal exclusively (possibly with an alumina tube which could keep the anode and cathode separate), and then flush the cathode chamber with inert gas exclusively. It's a little trickier than just putting everything in an inert box, but still doable probably. I'll be using this kind of design in some future videos... hopefully.
The other issue is that nitrogen is not inert enough to be useful as a protective gas. Calcium - and basically every reactive metal I've made so far - reacts with nitrogen and can even burn under nitrogen very easily (in fact, at room temperature, calcium reacts with nitrogen faster than it reacts with oxygen - so does lithium). Argon is pretty much the only inert gas option here, and it's considerably more expensive.
Glad you enjoyed the video!
@@ScrapScience That makes perfect sense, thank you! I had no idea it could react with N2.
FWIW, if you invest in argon, it gives you an excuse to also pickup a TIG welder. I have that set up and it is very satisfying to do, and handy to be able to make clean welds on steel and aluminum whenever needed. This also lets ya do high-vac science more easily But yeah, the cost and presuming nitrogen would work is why I didn't mention it.
You should make some nitric acid rockets
I don't know mutch about Making calcium this way but I do know a little bit about electronis. It appears to me in the video that your wire is touching the top of the crucible before it goes into the Liquid. Wouldn't that Cause it to ground out before it gets to the Material. What do you think?
It definitely looks like that on the footage, yes. However, I can guarantee that it was not actually touching the sides of the crucible anywhere (instead, it was hovering just to the side of the graphite).
If it were actually touching the crucible in any way, it would definitely short out and stop any electrolysis from happening, as you've noted.
Try Barium next time! ❤️ this!
I'm a little too scared about the toxicity of barium to try that one any time soon. I can almost guarantee that we'll be doing it at some stage though.
Very interesting. What electric forge are you using?
Glad you enjoyed!
As for my furnace, this is the one:
https://www.ebay.com.au/itm/383840249919
Chuffed for you mate
Do you think you could recover neodymium metal from broken neodymium magnets?
The separation of neodymium compounds (or at least, rare earth mixtures) from magnets shouldn't be too hard, but the isolation of the metal itself might be a tricky one. I've never tried any electrolytic processes with the rare earth metals, and I don't have any plans for it right now, but it'll likely be something we try eventually.
Well if it's soluble in molten salt, then I would assume, that if you start with small amount of salt, you would be able to electrolyze a lot of it, leaving you with the calcium?
I'm definitely not an expert in how metals actually dissolve in molten ionic salts, so I'm honestly pretty clueless in this regard. From what I've heard, it seems like increasing the concentration of dissolved metal in a molten melt generally makes the mass conductive to electrons before the metal can 'precipitate from solution'. In these cases, you just end up shorting out the cell (preventing electrolysis) instead of getting metallic product.
With a bit more research on calcium solubility in calcium chloride, some state that the metal dissolves via a comproportionation reaction to form calcium(I) chloride. This is very interesting if true, but it makes it impossible to form the metal by reaching a saturated solution, since the metal is no longer in its fully reduced form.
@@ScrapScience Good point, I am pretty much clueless as well...
А из расплава ацетата натрия ,натрий можно добыть электролизом ?
нет
@@ununeniy5843 понятно. Спасибо.
Nope. Sodium acetate decomposes significantly when you melt it, leading to side reactions during electrolysis and preventing sodium formation.
@@ScrapScience thanks , this is very valuable information for me.
Is it calcium or just calcium carbide generating acetylene instead ?
If it was acetylene burning there would be little flakes of carbon (soot) floating around
Interesting. I've checked the beads with a multimeter and they appear to be conductive, so I'd definitely say that they are unlikely to be calcium carbide.
@@ScrapScience As I know Carbides conduct heat and electricity.
yay
why not use calcium hydroxide?
Calcium hydroxide decomposes before it melts - turning into calcium oxide. Since our salt needs to be molten for the electrolysis to work, we'd require temperatures of over 2600 C to liquefy the oxide. It's just a whole lot easier to melt calcium chloride.
@@ScrapScience makes sense!
I read the thumbnail as “making children metal”
what if you made magnesium metal
As it turns out, I've already given it a go and have had success with making magnesium. No video yet, but I made a post about it not long ago.
The video won't be up for a long while I'm afraid - there are three or four other videos in the backlog before I'll be posting it.
@@ScrapScience cool
i think i'll love you more than my teachers ,, and that is really big ..
but i'm attempt to share knowledge with you ,, so i'll try to be helpful to you
You could possibly light the hydrogen on fire 🔥 to show the properties?
But it was a great video all the same!!
To be honest, I didn't even think of doing that. Would have been much more convincing that the gas was hydrogen.
I'll have to remember for the future. Thanks for the idea!
Make pure silicon
One day we will. No plans right at the moment though.
neat!
We don't see you too much make hydrogen peroxide process
"promo sm" 😏
C A L C I U M
I'm thinking, hardcore tactical shotgun shell additive, 25% calcium buckshot, feel the burn. Coat each calcium pellet in wax.
C A L C I U M
@memejeff - 2023-12-21
always amazing to find a goldmine science channel like this.