Scrap Science - 2022-01-13
In this video, we have a go at a very interesting and historically significant high temperature electrochemical experiment. The Castner process involves the electrolysis of molten sodium hydroxide, generating water and oxygen on the anode, and sodium metal on the cathode. This is the procedure originally used to isolate sodium, and served as the industrial route for its production for some time. By electrolysing a molten bath of sodium hydroxide, we are capable of making and extracting around 0.54 g of metallic sodium from about 90 minutes of work, which isn't too bad for a 'proof of concept' run. You can find my videos on making sodium hydroxide here: Explainig how it works: https://youtu.be/TTAg4F5sIYw Optimising the process: https://youtu.be/OrEQkBOxmxg Building a sodium hydroxide generator: https://youtu.be/iZH5fB0iM7U You can also find a similar video of mine, about making aluminium metal, here: https://youtu.be/aSx59lbc5cg
Nice to see you presenting in videos now! Your confidence in making videos shows, making for great content. More science than scrap! :)
I did this a while ago with a nail and a rusty smelting ladle. I got only milligramms of sodium but the nice thing was that all the rust went away and the ladle was in better condition than before the experiment
Wow, those globs of Na forming were so cool. Great experiment, thanks for sharing! Cheers!
Thanks for a good video on an odd but interesting process. I've long known the process for aluminum but never investigated sodium. I suspect the same process or similar can be used for potassium. I enjoyed the fact you showed your failure, analyzed it, and resolved it. The "little glitches" happen in almost anything one does, less than straight forward. Thanks again.
Thanks! Glad you enjoyed the video.
Interestingly, trying this particular process for potassium doesn't yield good results. The issue of the metal being soluble in the molten mass is much worse when working with potassium and potassium hydroxide.
Sadly, from reports of many people trying it, there is no temperature range or setup which can yield potassium like this. With an inert atmosphere, some have been able to make milligrams of the metal (without being able to recover any), but I’ve never seen anyone extract potassium like this with any success.
The electrolytic production of potassium requires melting a different salt, which I'll hopefully be attempting at some point.
I absolutely love your videos everything about them!!! Most of all I love how serious you take safety
Excellent project! Going to add this to my projects to make list 👍
You need more recognition, this is wonderful! Definitely sharing your channel with my fellow dangers to society!
I really dont have time for this right now -- can you help my cat he has loose bowel movements and refuses to eat his har
@Tim Perfetto mix shed fur with a smooth paté wet food, as much hair as you feel is necessary
@Holy Robot Thats a good idea thank you I am worried if he doesnt eat enough hair he will spontaneously combust
@Tim Perfetto add CCl4 to prevent combustion
@Holy Robot How rude of you -- he already has liver issues and what do you think I am a dry cleaner?
Oh my goodness, this is the first of your vids i have watched, i am 40 seconds in and you have mentioned that three videos with no electrochemistry is your limit. I subscribe ! I am going to enjoy your chanel, of that much i am sure already.
Use 80% NaCl and 20% NaOH, use screen of course seel wool as the separator spot welded to a cheap steel pan. use a big block of graphite rod as the anode and a steel plate as cathode. A big flower pot works well for your crucible, seal your rod with pottery clay and pack it in sand. If you get it hot enough you will get sodium as a vapor. Condense with a steel tube into mineral oil.
Well explained and good effort mate.
Me and my uncle put ordinary table salt in a stainless steal cup, much like what you have there, and stuck it in his ceramics kiln.... THAT... did not end so well....
From what we could tell from the damage, it first reduced (well, oxidized, actually) the entire stainless container into some kind of super rust. It then fluxed the rust to the point that it was soluble enough that it could soak into whatever brick the kiln shelf was made of. It then proceed to drip down through the bottom of this shelf, and onto the pieces underneath, largely fluxing and dissolving them, melting them to the shelf they were on. There was apparently some gasses, or eruptions, during this whole process, since just about everything in the kiln had molten splatter marks on them.
Needless to say, turns out, salt is about the worst thing you can put in a kiln.
Chlorine gas!!! 😵😵😵😵
Thanks for including your "failures", most people think they are BAD to include, which tells you something about how they approach science.
Yup that is helpful information 👍
What happens if you crank the heat and let the sodium dissolve into the melt and then start slowly cooling it? Will it recrystalize?
I tried a version of this in the 1970’s with NaCl on my mother’s electric range, fortunately failing completely. The NaCl melting point is 483 C higher than NaOH, and the range just couldn’t quite reach 801 C. Information was so much harder to find then!
I actually know of quite a few people who have attempted direct electrolysis of molten NaCl, and I've never heard of anyone successfully extracting sodium from it, so don't feel bad! Combining temperatures of over 800 C, molten sodium, and hot chlorine gas is a pretty tricky thing to try to handle.
I can't quite imagine what home chemistry would have been like in the pre-internet days (much more difficult I'd imagine), so I really admire the fact that you gave it a go anyway.
@Scrap Science I'll try to build a Down's cell hopefully this year. The only videos are from industrial scale operations. I'm curious as to how hard it is to pull off the downsize. I'm more worried about the chlorine, as I'm not well versed in gas manipulation.
@Scrap Science you mentioned there is a better way that was discovered to produce sodium after 1920s what is that method??
@First Last The Downs' process is the one. It involves electrolysing molten sodium chloride instead of sodium hydroxide. I talk about it very briefly at about 7:50 in this video.
Neat. It would be great to know what the settings were for the electrolysis.
I just had it connected to 5 volts DC (capable of 25 amps maximum) in this case. Nothing else to it.
if you do high temprature electrolysis you would get very reative cathode mass, that contains NaH and Na2O from reaction: NaOH+2Na=NaH+Na2O(at 500C)
Have to cover the beaker with the sodium and water so hydrogen can get more and will ignite spontaneously. Or put the piece of sodium in some paper and then drop it in water. Gives similar effect
you could extract the sodium, then burn it in pure oxygen to get sodium peroxide, which can be used in co2 scrubbers, dropped in water to produce sodium hydroxide and hydrogen peroxide, or whatever you want to do with it.
Hi, I wanted to make this experience last summer but couldn’t manage to have a stable temperature of around 320ºc. Would you have any recommendation ? I already have a home made charcoal furnace but it goes to 800ºc and that’s a little bit to much😅.
That's definitely a tricky thing to try to get temperature control with.
If you work on a small enough scale, it might be possible to heat up your sodium hydroxide with your furnace, and then remove the molten mixture from the heat source, and keep it molten with just the current of electrolysis.
That way if it gets too hot, you can just turn off the current, and allow it to cool a bit before turning the current on again.
It might take a bit of work to get the temperature balance right, but others have succeeded with this kind of setup before.
Brill. Very well explained and really interesting thanks
I really like this channel. Electrochemistry is cool.
One of the only channels I clicked the bell icon for and I still don't get notified about your videos. :(
Keep making amazing videos
Thanks mate, glad you like the channel!
Hopefully Youtube fixes their notification system soon, but sadly I'm not counting on it.
Nice to see that it actually works in a homelab scale - I've never succeeded wirh this before... 😞
this channel is awesome keep it up!!
I used two iron nails years ago and it worked well.
Just be very careful with the hydrogen production, one time when I was making sodium metal, the hydrogen mixed with the oxygen, then exploded and I almost gave myself a piercing.
Did you make it in a garage?
I would really like to see how nickel would behave as an anode
This is actually really interesting! I hope this channel blows up
Nice work man (: I'm glad your channel popped up in my feed. We seem to have common interests. Have a subscriber my good sir!
Thank you for sharing that experiment. Interesting.
Very interesting processin home conditions. I will be waiting for for next videos, thnaks for your work and
YT activity. Best for you from Poland
Take a small glass tube, maybe 12' long. As the sodium bead is bouncing around on the water catch the bead with one end and light the gas being given off by the sodium..
The graphite anode is nice because it seems the sodium doesnt explode as it forms in the cell unlike with a nickel anode maybe because the O2 makes CO2 at the graphite anode?? which then forms sodium carbonate try to see what that solid mass is whether its pure NaOH or a mix of that and carbonate.
I like this idea, makes a lot of sense.
Sadly, I've already neutralised all of the waste from the cell, so I might have to do some further testing at some point...
The leftover on the pan was very likely sod carb because sod hydroxide will dissolve in water real fast.
Yeah, the hydroxide was stained right away. Not all stainless steel is true stainless, often its just chromed steel, which wont survive the hydroxide and contaminates your product. You have to splurge for the real stuff as it is considerably more expensive, but true stainless will be much tougher to the caustic.
I put it this way: it's stain*less*, not stain*proof*. It's good for ordinary weathering conditions -- moderate pH, lots of water, chlorides even, but isn't so great at extreme pH. (Still good at high pH, though beware of trace chromates perhaps? Low pH, dissolves just like anything.)
And even then, it's not perfect by itself, it needs to be surface treated (passivated) to prevent staining; this normally involves something like, dissolving off the surface layer of iron with citric acid, ensuring a tight chrome oxide surface.
Sodium hydroxide is very hygroscopic. try vacuum desiccation on the solid, might help.
great video, you can clean the sodium if you add under mineral oil (VERY GENTLY!) few drops of ethanol, the reaction should clean up the surface. test it, but be prepared and very careful
As it turns out, this is exactly how I cleaned and coalesced the sodium droplets - though I ended up using isopropanol instead. I didn't really show it in the video, but it definitely cleans up the sodium very nicely.
@Scrap Science nice, i note that, if i somewhen make sodium metal by myself :D i got an induction heater that makes very fast iron pipes glowing red, the same is for graphite i think. i like that method... hmmm sounds like a video idea :D
@Scrap Science another suggestion, if you over volt the electrolysis, the excess voltage turns into heat, i think if its molten you can keep it molten that way.
Great video chief! Your channel is kick ass
I understand that a eutectic of sodium iodide and sodium hydroxide would lower the melting point considerably and reduce the solubility of sodium in the melt (preventing the need for precise temp control). I have yet to find anyone who has reported any results, however.
As far as I can tell, the sodium iodide/sodium hydroxide eutectic is only applicable for electrochemistry when the anode is a sodium alloy in the first place (i.e. it’s only good for electroplating sodium rather than isolating it from the salt).
I would strongly suspect that the iodide would interfere if you tried this with inert electrodes. I’d predict that the anode would generate iodate and/or hypoiodite ions as the oxidation product on the anode, and would then prevent sodium formation due to the presence of these oxidisers in the melt.
It might make a few milligrams of sodium, but I doubt it’s capable of making much more than that sadly.
NICKEL FOR THE CATHODE,& GRAPHITE FOR THE ANODE (NICKEL CAN BE USED FOR THE ANODE ALSO). FOR MAKING SODIUM METAL BY PUTTING MOLTEN SODIUM HYDROXIDE (LYE) THROUGH ELECTROLYSIS.
NaO melts at 1132 °C, but with graphite mixed in.. what are the odds that Na2C2 is formed?
I store my sodium in water, it lasts much longer that way! 😁
it's nice noone has to mention "don't drink molten NaOH" any more 😁 humanity has some hope ;)
Just pointing out, most sodium hydroxide purchased from a hardware store will be a monohydrate.
Great Video, looking forward for NaCl electrolysis!
i tried the nurdrage method using menthol as a catalyst but mine failed and chewed up the flask.. i think my sodium hydroxide was to wet even though it was out of a new container.. i haven't tried drying sodium hydroxide yet, does anyone know if calcium chloride is good enough to dry sodium hydroxide? or any other good way to dry it.. some motorbike and aircraft parts are made of magnesium and i'm keeping an eye out for magnesium scrap because the thermite method works really easy and has a 40% yield
If you can dry it with CaCl2 in a vacuum or reduced pressure, I'd guess you'd have better luck
I did the nurdrage method with dioxane and it worked very well. It ate up one of my flasks, but I anticipated that and used a cheap one.
I also used extremely fine magnesium powder and ground the sodium hydroxide up very fine.
@TeslaFactory yeah I just don't know yet who's going to win at absorbing the water since both sodium hydroxide and calcium chloride make really good desicates.. when I have time I'll stick both in my drying box and see who wins
@Anthony Sutliff the method with dioxin was the thermite reaction in a soup can and the sodium is separated out in the dioxin and shouldn't eat the flask, mine didn't eat the flask with the thermite and dioxin method.. maybe I missed something but the wet processes all used paraffin oil to my knowledge and it was the wet process that ate my flask
I Have Recently Made Pure Sodium Nitrate Salt And When I Was Heating It With A Beaker It Melt, Isn't Using It Instead Of sodium Hydroxide Better ? Because Molten NaNO3 Is A Lot Easier To Handle Than Molten NaOH Which Isn't Only Very Hot But Also Far More Corrosive (When I Used Cheap Stainless Steel Container To Handle It The Container Oxidized)
Sodium nitrate is far too strong an oxidiser for this to work I'm afraid. While the electrolysis will proceed, any sodium you make on the cathode will instantly react with the molten nitrate. In fact, it's much more likely that the cathode will simply reduce nitrate ions instead of sodium ions anyway.
Amazing stuff. Subbed
That's trace water in the oil its reacting with, and a common method for drying it.
Thank you for this. Now, not that I'm going to try this, when they electrolize salt water to bubble chlorine out, what happens to the sodium? Does it combine with the OH in the water to make NaOH and bubble hydrogen? And if so, how to they get rid of the hydrogen in the gas? Burn it?
In a solution of sodium chloride, the cathode reaction actually reduces water to hydrogen directly - sodium ions are much more difficult to reduce, so don't take part in the reaction at all.
If you were to try this in an undivided cell, you'd eventually end up generating sodium chlorate (which I have a video about, https://youtu.be/N45DlWLQ218 ), and if you manage to separate the anode and cathode reactions, you'd end up with the industrial process for making NaOH (which I also have a whole series of videos about, starting with https://youtu.be/TTAg4F5sIYw ).
@Scrap Science Thank you so much. I hope you don't mind another couple of questions. When you do Castner in a stainless steel crucible, (1) wouldn't you get some current through the stainless steel, and (2) if so, would this have something to do with corroding the stainless steel?
No worries, I'm always happy to answer any questions in the comments!
With the stainless steel crucible, there won't actually be any meaningful current flowing through it - provided the electrodes aren't touching the edges of the container in any way. The reason for this is the fact that the molten sodium hydroxide is only conductive to electric current in the form of ion migration, whereas the stainless steel is only conductive for electrons. The electrodes themselves (being connected to the external circuit) perform their respecive reactions as a way of essentially converting 'electron current' into 'ion current'. Since the crucible isn't connected to the external circuit, it won't conduct or take part in the reaction.
As for your second question, the corrosion of the stainless steel is simply a consequence of the high temperature and the intensely corrosive nature of the molten hydroxide. If you were to actually use the crucible as one of the electrodes in the process, you'd observe one of two things:
1) If you connected the crucible to the negative terminal of the power supply, the cathodic (reducing) conditions would protect the metal from corrosion to some degree. However, the surface of the crucible would then start making sodium over the whole surface, producing tiny beads of the metal all over the place, and making it more difficult to collect the product.
2) If you connected the crucible to the positive terminal of the power supply, the anodic (oxidising) conditions would rapidly corrode the stainless steel, probably etching through it in a few minutes I would think.
@Scrap Science you can do that if you an electrode that has high overpotential for H+ ions; for example mercury. then sod will dissolve in Hg and you will get a dilute amalgam
Thanks again. The ion transport stuff sounds like how dendrites and axons work. It annoys me when people call that electrical, because there are important differences, such as speed. I know more about organic chemistry, but in prison I had a chemist friend, now I can write him and impress him with the name Castner. I always eat organic food because inorganic food is usually way too crunchy.
Scrap Science - 2022-01-13
I didn't mention it in the video, but if you like the idea of making sodium, you should also check out Nurdrage's video on the topic. While most of you have probably seen it already, he developed a completely separate method for sodium production a few years ago which uses much milder conditions, gives better yields, and is overall much more friendly for home chemistry:
https://youtu.be/BsNoiFj3wlw
This is a much better route for making moderate quantities of the metal.
dksmith605 - 2022-01-14
Sodium production via wet chemistry is definitely on my to-do list, but whether to obtain the jump-start quantity by another method or sacrifice some glassware.
I might attempt the reaction in a soda-lime flask, because they are cheaper to destroy.
Thoughts?
I'd be very interested to see other alkali metals isolated via wet chemistry.
ChemTalk - 2022-01-14
Thanks for the link. We've seen his videos on sodium production, have you tried that method? From what we've read it is difficult but not impossible to replicate. We have not tried it ourselves.
Michael Fischer - 2022-01-15
Nurdrage's method works great. The Baby oil is much thinner than "Normal" laxative type mineral oil and and is closer to the material used in the Potassium videos. While normal mineral oil worked, yield was much smaller and just small balls of Na. I just completed my second run using the baby oil and I got 1 solid 15 gm blob of sodium, 1-2 gms were used as the starter. I used the thermal Mg/NaOh method for the original "starter" . 3 Batches made, all worked and the 2 baby oil bathes had giant lumps. One key I think, is when it is done, prop the flask at a slight angle, stop stirrer, reduce heating, wait about 1/2 hr, then turn off heat. This allows sodium to join into large mass.
Scrap Science - 2022-01-15
@dksmith605 That’s definitely an interesting idea. I’d be extremely wary when bringing soda lime glass to high temperatures like that though. A good oil bath is probably essential here.
If you try this, just make sure you’re fully prepared for the glass to (possibly violently) shatter at any stage.
Hope it goes well!
Scrap Science - 2022-01-15
@ChemTalk As much as I’d like to, I’m afraid I’ve never tried it at this stage.
Similar to you, I’ve seen quite mixed reports on whether or not people can get it to work. Some describe easy success, while some don’t get anything even with a seemingly perfect setup.
I still haven’t been able to determine what differentiates the successes from the failures, but once I can get hold of some magnesium, I’ll be giving it a go myself at some point.