Greetings fellow nerds.
Time for another review of what i've been doing in the lab and my notes on it.
Let me give a brief recap of projects i've been working on.
The biggest project right now is making sodium by the alcohol catalyzed magnesium reduction approach.
So far i've been very successful and can produce sodium on a reliable basis.
Basically mix sodium hydroxide, magnesium metal, some tertiary alcohol, mineral oil as the solvent
and heat the mixture to 340 celsius on a hotplate and after three days we get sodium.
The current big problem with the process is that the reaction mixture is highly damaging to the glassware.
This makes sense since sodium hydroxide is well-known for dissolving glass, especially at higher temperatures.
In previous lab notes videos i've been trying to coat the glassware or find better solvents.
So far the results haven't been very good.
Sodium silicate coatings are promising but my first attempts were too porous.
I then tried different solvents like dioxane and dimethyl dioxane but their boiling points were far too low.
Interestingly, I had a lot of suggestions in the comments of those videos so i'll try to address some of them here.
Some people have suggested teflon or PTFE coatings, or even using whole teflon or PTFE apparatus which can easily be bought online.
Unfortunately, Teflon is actually reactive toward liquid sodium.
It cannot be used as a container material.
In fact, i already proved this with the PTFE coated stir bar and showed that it was degrading as i used it for these experiments.
It's slow but it's happening.
PTFE labware is even more expensive than borosilicate labware so we would have made our degradation problem even more costly if we went with PTFE labware.
But don't feel bad my fellow nerds.
PTFE labware wasn't a bad idea and understandably the knowledge of PTFE being vulnerable to molten sodium not that well known outside of chemistry circles.
And now you know.
Others have suggested, resin, plastic, polyethylene, acrylic, varnish, basically all kinds of hydrocarbon based coatings.
None of those are viable because they'll all melt and dissolve in mineral oil at high temperature.
Another suggestion was an internal coating of metal.
The thing is strong metal coatings on glass aren't that easy for the amateur.
The easy ones like silver are too weak and would be ripped off by the constant stirring.
And in the end, if we were going to go with metal, we might as well just use cans or plumbing pipes.
Another problem is that metal is opaque and we can't see what's going on if we use it.
Some people had suggestions for attacking the boiling point problem.
The most common one was to use higher pressure to raise the boiling point of the dioxane and possibly access higher temperatures that way.
I'm staying very far away from high pressure reactions, especially high temperature ones, due to the safety concerns.
What makes this reaction even harder is that it's a gas generating reaction since it produces hydrogen.
So the pressure will actually increase as it runs if kept in a closed system.
This is incredibly dangerous and even professional chemists have been killed from exploding pressure vessels.
We'd need to build a vessel that also has a pressure relief mechanism to release the excess hydrogen gas.
Unfortunately this goes well beyond the reach of the amateur.
The point of the research was to make sodium accessible to the amateur, not push it even further away with the requirement of specialized equipment.
If we were going the specialized equipment route, I'd say let's just make a Downs cell or a Castner cell and be done with it.
I'll probably do that in the future, but for now i just want to stick to normal glassware.
So anyway, these past few weeks i've been exploring another other aspects of the sodium production process.
Mostly i've been examining under what conditions it works and how to optimize it.
I'll get back to finding solutions to the glassware destruction problem
but sometimes it's helpful to first do as much optimization as possible with existing methods.
And in the process learn more about what's going on.
Now judging from the dioxane and dimethyl dioxane experiments,
it seems that trying to run the sodium production reaction at low temperatures isn't going to work.
So i ran a series of experiments to try and find the minimum necessary temperature for the reaction to start.
Unfortunately, every time i got hydrogen formation, indicating that the reaction had started, i also had damage to my glassware.
I wasted many days and destroyed several flasks running these tests.
Oh well, it wasn't a total waste.
After running those experiments i developed a few techniques to better the process and recover the sodium.
In my original experiments i poured off the magnesium oxide and mineral oil slurry and pulled out the sodium with pliers.
This was frustrating work and ran the risk of breaking the glassware.
The better approach I found was to gently slow down the stirring over the course of an hour to let the sodium coalesce.
Then the stirring was stopped before turning off the heat to just let the sodium solidify into globules.
Once it was completely cooled, I simply used a kitchen sieve and strained out the sodium.
The magnesium oxide and mineral oil remains as a slurry while the larger sodium globules are retained.
Very large sodium globules will remain stuck in the flask but these were much easier to pull out with pliers.
Nonetheless i figured out later i didn't even need to do that much, but i'll get to that in a bit.
The strained sodium is still covered with magnesium oxide and mineral oil so it was washed with dioxane.
And there is our sodium metal mixed with magnesium metal.
To accurately measure yield we needed to remove most of the excess magnesium so the sodium was dumped back into a flask and boiled with dioxane.
We know from previous work in the thermochemical dioxane process that dioxane has special properties for separating sodium.
The solution was vigorously stirred to breakup the sodium into smaller spheres.
I realized that if I did this earlier, i wouldn't need to use pliers.
So from now on i'll be using dioxane boiling and stirring to breakup larger sodium spheres into smaller ones.
Anyway, stirring was stopped and the mixture allowed to cool.
Straining out the sodium and leaving the magnesium behind we now have cleaned sodium metal.
There is still a minor amount of magnesium on the sodium but this is just a surface coating.
I confirmed this by cutting one open.
On average my yield was in the range of 60% to 70%.
This is a considerable improvement over the thermochemical dioxane process that gives a yield of around 40%.
And much better than our first breakthrough at 33%.
Most of the improvement was just better reaction time and more careful technique.
Although having full sodium recovery by using a kitchen strainer helped as well.
Overall i like this improved technique better since it's cleaner, much less labor intensive and involves breaking far less glassware.
Unfortunately all of these experiments still involved damaging glassware due to reaction with sodium hydroxide.
So i'm still working on that problem.
Now I've been doing other routine labwork while i waited for the reactions to happen.
One of them was restocking my supply of hydrobromic acid.
I used it all up when i was making alkyl bromides to in turn make the tertiary alcohols for our sodium experiments.
Now i already made a video on this some years ago so hydrobromic acid is nothing new for us.
Basically react an acid with sodium bromide, make hydrobromic acid and distill off the hydrobromic acid from the salts.
This time i used sulfuric acid to make it rather than sodium bisulfate and got fairly good yield.
A big improvement over my old method was in the bromine removal step.
Small amounts of bromine would often contaminant the hydrobromic acid because small quantities are made from the reduction of sulfuric acid.
In my old video i used copper metal to react with the bromine and consume it as copper bromide.
This worked to some extent but didn't remove all the bromine.
There was lingering contamination.
While inconsequential for chemistry it was unsightly and gave the impression the acid was crap.
I've since come up with some much better approaches.
The first is to clear the bromine using elemental sulfur.
Sulfur is very cheap and easy to obtain and reacts with the bromine to make more hydrobromic acid.
So it's more effective and more efficient than copper, a double win.
Unfortunately it also clouds the resulting hydrobromic acid so you have to reflux it to get it out.
An even better method was to use a small amount of sodium metabisulfite.
It's a reducing agent and rapidly reduces the bromine into bromide ions.
After distillation you get clear and pure hydrobromic acid.
A quick question for you guys though.
Would you like to me make a separate video on the new and improved method for making hydrobromic acid?
I'm actually making more right now and it wouldn't be too hard for me to film it while doing so and making a full video on it.
I want to ask because i already have an old video which admittedly is not very good but maybe you'd rather i only stick with new chemistry,
the update in this lab notes video being adequate for updating the old procedure.
Let me know in the comments.
Another actual video i've been working is this Clevenger apparatus.
The Clevenger is not some superhero pornstar,
it's actually a type of Dean stark apparatus but can be used in both light return and heavy return modes.
It's not as good as a specialized apparatus but it's less expensive
and thus it's a great addition to any amateur's labware collection when you don't need professional level performance.
I'll be releasing that video soon.
So that's what i've been working on these past few weeks.
At this point i want to ask the question if you like this current format where i detail everything i'm doing in the lab notes videos
or if you think it's better i make separate contained lab notes for each topic.
A combined format guarantees i cover everything and even mentions topics that would be far too short for a self-contained video.
But separate self-contained videos would be focused and not jump around topics like this one does.
I can do either one, let me know how you want it done.
Anyway, thanks for watching.
Things are progressing.