Sciencemadness Discussion Board - Make Potassium (from versuchschemie.de)

Make Potassium (from versuchschemie.de)

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BobD1001 - 3-7-2013 at 10:46

I'm outside Philadelphia, near King of Prussia, Pennsylvania.

blogfast25 - 4-7-2013 at 06:24

Can't help you with that, sorry (ole' Blighty)...

BobD1001 - 10-7-2013 at 20:56

Well everyone, after 6 attempts, much frustration, and coming close to giving up.... I have finally successfully produced elemental Potassium!

From what I have gathered after attempting this synthesis 5 times previously (with failure might I add) using a 95% pure Mg alloy, the remainder being Al, it seems that the purity of the magnesium is important for the reaction. Of course that may still be open to debate and it could have other unknown errors in my previous runs, however all were documented extensively in my lab notebook, and I believe I have isolated my issue to the purity of the Magnesium being used.

This 6th run was performed following one of my previous runs lab notes exactly, however I had a new source of Magnesium. This new Magnesium is stated as 99.95% purity, from galliumsource. Pretty expensive for a little ingot of Magnesium at $15 for .5lb, but well worth it to be able to say I have produced elemental Potassium.

Anyways here are a couple pictures! currently I am trying to coalesce the Potassium into larger globules.

Sorry the pictures are somewhat poor. There are thousands of tiny potassium balls all about the flask, however this picture only shows the 2 larger globules formed so far.

I will further update with better pictures shortly.

[Edited on 11-7-2013 by BobD1001]

blogfast25 - 11-7-2013 at 02:53

What was the run time at this point?

It does seem a consensus is building on the importance of the magnesium.

Sublimatus - 11-7-2013 at 03:37

I've still had no success with this reaction after many attempts, to the point of nearly losing interest.

My source of magnesium in the later reactions has been the 99.95% thin turnings offered by GalliumSource, which I then threw in a coffee grinder to reduce down to finer chips, and then roughed up in a mortar and pestle wet with some of the solvent used for the reaction.

Seeing BobD1001's success, I may order one of their rods or ingots and grind off some powder with a file, as I did with a sacrificial anode I had lying around from RotoMetals for my first few attempts at this.

If that doesn't work, then that should indicate pretty definitively that my hangup is some other factor, such as the solvent, KOH, or reaction temperature.

BobD1001 - 13-7-2013 at 09:36

Just to update my progress a bit:

I had to cut the reaction somewhat short on my 6th attempt (my previous post) so the potassium formed was not a very significant quantity nor did it have the proper time to coalesce. In my naivety of how difficult it would be, I decided I would just spend some time plucking each little potassium ball from the reaction liquor and accompanying MgO, Mg fines/flakes, and remaining KOH. Well it turns out it was ridiculously difficult, and I only obtained a few small balls of elemental potassium. In my next attempts, I will be sure to run the reaction much longer to allow full potassium formation and coalescence. However, I really just wanted this sample for my element collection, and now have it! Here is the very underwhelming final result!

I do have to say however that i may have ended up tossing a couple other little potassium globules into a big bucket of water to see the famed reaction. Also of note, I simply reacted away the potassium fines into that same bucket of water (make sure you do this outside, as much smoke/vapor is emitted, which I'm sure contains a significant amount of KOH). It was unbelievably pleasing to see so much potassium auto-igniting upon contact with water emitting a beautiful violet flame.

BobD1001 - 13-7-2013 at 13:41

Already getting ready for my next batch. I decided to really get some fine magnesium turnings/powder for this next run as opposed to using chips from drilling holes in the Mg as I used last time, so I decided to use my milling machine, and a cardboard box to catch the 'chips'. I took a couple thousands of an inch off for each pass and performed each pass very slowly, and totaled 7g of very fine magnesium chips (basically extremely high surface area flake particles). I also made a gram of very fine filings to help with the initial dehydration step. Here's a couple pictures of the setup and magnesium to be utilized.

I hope everyone doesn't mind me posting so many pictures. I'm a huge fan of pictorials, and find them highly useful throughout my own ventures in chemistry.

[Edited on 13-7-2013 by BobD1001]

blogfast25 - 14-7-2013 at 04:39

@Bob:

These look perfectly fine (no pun intended) Mg turnings/shavings. Nice little vials too: where did you get those?

Try and ensure good temp. control (approx. 200 - 220 C) and run long enough (about 4 hours with conventional heavy hydrocarbons solvents). Stir or swirl the flask occasionally if you can.

[Edited on 14-7-2013 by blogfast25]

BobD1001 - 14-7-2013 at 08:09

@blogfast25: The vials were found on Amazon. They are actually the first listing to come up for 4 dram vials from the seller MHB, however they seem to send everyone the wrong item which are these little bottles.

I ran the experiment yet again last night, with limited success. It produced potassium after T=4 hours, however the entire reaction liquor was grey (I'm guessing from MgO and K fines floating around) and the only potassium globules formed were small again. I had my hot plate set to 270C, and the reaction vessel sitting at the bottom of the sand bath. The grey suspension refused to settle after another two hours. Upon dumping the reaction liquid into a large beaker to search for potassium globules, it was apparent that nearly all the Mg was consumed in the reaction.

Perhaps my solvent (ultra pure paraffin oil in this case), is too thick, and allowing a suspension to form? Also, when we say run this reaction at 200-220C, are we referring to the hot plate temp, the sand bath temp, or the actual reaction vessel temp?

elementcollector1 - 14-7-2013 at 08:31

Sand bath temp, although the heat of the reaction does need to exceed 200 C.

blogfast25 - 14-7-2013 at 10:03

Quote: Originally posted by elementcollector1

Sand bath temp, although the heat of the reaction does need to exceed 200 C.

Better put, the temperature of the reaction mix should be a about 200 C, probably +/- 10 C.

@Bob: thanks for the tip on the vials.

[Edited on 14-7-2013 by blogfast25]

BobD1001 - 17-7-2013 at 13:46

I just ordered 500mL of Tetralin. Pretty expensive stuff! 500ml for $37 with shipping, but none-the-less I should finally be able to get some great coalescence. Also just for completeness I added this synthesis to my website where my process is fully documented rather than in bits and pieces like it is here. http://www.doranaerospace.com/Potassium.html

bfesser - 17-7-2013 at 13:52

One suggestion for your page; recognition of versuchschemie.de would be appropriate.

[Edited on 7/17/13 by bfesser]

hyfalcon - 17-7-2013 at 14:43

I've found a source of 1-Pentanol if anyone is interested. I'm going to post the link in the new suppliers thread if anyone wants it.

BobD1001 - 17-7-2013 at 17:07

Quote: Originally posted by bfesser

One suggestion for your page; recognition of versuchschemie.de would be appropriate.

[Edited on 7/17/13 by bfesser]

Just added credit for the thread at versuchschemie.de. I appreciate the input bfesser.

BobD1001 - 17-7-2013 at 20:57

Did anyone on this forum happen to download/save nurdrages video(s) on Potassium production? Although I have successfully produced potassium, I would love to see his techniques, as it may give me better ideas as to how quickly my solvent should be refluxing... I just know something isn't quite right in my reaction conditions due to lack of coalescence.

DrSchnufflez - 17-7-2013 at 21:42

Yes I did save his potassium synthesis video, I don't know how to send it though

bfesser - 18-7-2013 at 03:58

<strong>DrSchnufflez</strong>, if you can upload it to the <a href="viewthread.php?tid=603">/scipics/</a> directory, we could access it from there.

blogfast25 - 18-7-2013 at 08:29

BobD:

Tetralin is what Nurdrage used in one of his experiments. Total reaction time plus coalescence about 1 h, acc. NR.

hyfalcon:

1-pentanol is interesting but irrelevant in this context: only tertiary alcohols work here.

hyfalcon - 18-7-2013 at 12:17

That's also what they have as alternative name for t-amyl.

Vargouille - 18-7-2013 at 13:09

I daresay you mean "t-pentanol". 1-pentanol would be a primary alcohol.

blogfast25 - 19-7-2013 at 04:34

Quote: Originally posted by hyfalcon

That's also what they have as alternative name for t-amyl.

A t-alcohol can never be a 1-ol, it has to be a 2-ol or higher and even that is not a sufficient condition to be a tertiary alcohol.

hyfalcon - 19-7-2013 at 05:48

You know you're right. The CAS number is the same also. I'm going to call their hand on that and see what the answer is.

It should be 2-Methyl-2-butanol with a CAS #75-85-4.

[Edited on 19-7-2013 by hyfalcon]

blogfast25 - 19-7-2013 at 13:21

It's likely to be a 'cut and paste' error.

BobD1001 - 30-7-2013 at 07:21

Well here are the goods! Now time to make potassium in useful quantities. I plan to reuse the reaction solvent, given that it works for multiple reactions, as the Tetralin was quite expensive.

blogfast25 - 1-8-2013 at 05:27

Quote: Originally posted by BobD1001

I plan to reuse the reaction solvent, given that it works for multiple reactions, as the Tetralin was quite expensive.

Data on reuse/recovery of solvent/catalyst would be enormously useful.

Squall181 - 3-8-2013 at 16:58

I have been following this thread from the begging and have been wanting to give a go at this reaction ever since. Well, I finally got all of the reagents together and today I have become the newest member to grow balls of potassium.

After 3 weekends and about 8 different runs I was getting pretty disheartened, but with patience and perseverance I was able to get those balls.

Here is a picture of the reagents I used.

The beaker contains the larger potassium balls that I was able to pick out with tweezers.

I made magnesium fillings by taking a rasp to the Mg ingot seen in the picture.

The KOH was used as is, in flake form

The recipe was 2 grams of Mg, 5 grams of KOH, 1ml of T-butanol, 30 ml of paraffin oil. All this was added in the begging in the so called one-pot method.

Potassium balls were seen in the reaction mixture about 30min after the temperature of the sand bath reached 220 C. The 50 ml flask was swirled about every 20 - 30 minutes.

The collected balls were coalesced under heavier paraffin oil (Carolina science supply) into one large sphere. Pictured below. The fines were used to create a nice pyrotechnical show.

I would like to thank everyone who has contributed to this thread, this is an awesome synthesis that requires much patience.

My first very successful reaction!

BobD1001 - 3-8-2013 at 23:42

Thats an incredible job Squall! Congrats on the successful reaction, and kudos to not giving up!

I also performed another run today, utilizing tetralin as the solvent. It was by far my most successful reaction to date, producing quite a bit of potassium! But oh boy does the Tetralin smell! Just like naphthalene moth balls (kind of a DUH! statement there...) which is now on my sh*t list of smells. Really got sickening when cleaning up my glassware. Anyways, here are the photos of the reaction:

A color change of my solvent was noted nearly as soon as it heated up. this eventually dissipated.

Soon after, extremely tiny potassium globules could be seen all over the surface of the Mg turnings. Its not very visible in this picture, but I am including it for completeness.

After some time, there were some large balls of potassium forming, however, they were refusing to float as they should have (i believe it may have been oxides weighing the globules down)

Soon after the first 'floaters' appeared:

And finally, the end results!

blogfast25 - 4-8-2013 at 06:06

Well, congratulations to both Squall and Bob.

Bob's experience with Tetralin is not hugely encouraging though, considering the cost (and poor availability) of this solvent. Clearly the K is being weighed down by adhering cruds, inhibiting floating somewhat. This is somewhat different from Nurdrage's experience but IIRW he did use slow stirring.

Floating K would not only 'free up' space for new embryonic K balls to form, the floating K in the absence of cruds should coalesce much more easily. Bob's experience doesn't seem to unambiguously bear that out.

Bob, will you now try and recover the solvent + catalyst for a second run?

Additional point: so far, at least as far as I can remember, everyone has used flaked KOH (that's me included). I wonder if a ground form of these flakes (they grind fairly easily in a mortar and pestle - my experience in other pursuits) could provide some advantage. The way the slag (MgO) forms does seem to have some bearing on the coalescence of the K metal, although it is difficult to describe the relationship in anything but the crudest qualitative terms. And the physical form of the KOH may have some bearing on the physical form of the slag.

[Edited on 4-8-2013 by blogfast25]

Sublimatus - 4-8-2013 at 06:53

If anyone does grind their flakes, wet it with a bit of the oil you intend to use first.

I ground mine for most of my attempts at this reaction (all failures), and the first time learned how easily the dry dust can get into the air and sting your respiratory tract. It wasn't a medical emergency, but it also wasn't pleasant.

bfesser - 4-8-2013 at 07:04

I love seeing all of the successful preparations that are reported in this thread. It's so nice to see.

Sublimatus, I posted a <a href="viewthread.php?tid=3546#pid118075">suggestion</a> for grinding irratating powders some years ago, if it's of any help. You may even consider flooding the bag with dry nitrogen.

[Edited on 4.8.13 by bfesser]

Sublimatus - 4-8-2013 at 07:12

That's an interesting solution, thanks for writing it up.

In this case I simply wetted the KOH beads with the reaction solvent they were going to end up in anyway and ground them (things are a pain to grind, they bounce around like the silica beads you mention). It kept the caustic dust out of the air (and my lungs), and I would think kept some of the atmospheric water out that would've accumulated in it otherwise.

blogfast25 - 4-8-2013 at 07:42

Quote: Originally posted by bfesser

I love seeing all of the successful preparations that are reported in this thread.

Agreed but despite the extreme length of this thread we are still sorely lacking in knowledge in the following areas:

• Use of other 2-methyl-2-ols
• Influence of type of magnesium
• Influence of stirring/occasionally swirling
• Re-using of post reaction solvent/catalyst mix
• Other, more efficient ways of coalescing K metal droplets

I hope one day we will get to the bottom of most of these issues.

BobD1001 - 4-8-2013 at 08:59

Quote: Originally posted by blogfast25

Bob, will you now try and recover the solvent + catalyst for a second run?

Additional point: so far, at least as far as I can remember, everyone has used flaked KOH (that's me included). I wonder if a ground form of these flakes (they grind fairly easily in a mortar and pestle - my experience in other pursuits) could provide some advantage. The way the slag (MgO) forms does seem to have some bearing on the coalescence of the K metal, although it is difficult to describe the relationship in anything but the crudest qualitative terms. And the physical form of the KOH may have some bearing on the physical form of the slag.

I was hoping to recover the reaction solvent, but it was quite late at night and I was a bit too lazy to recover the solvent. I didnt have a great method of separating it from some remaining K fines and the MgO sand. I likely could have filtered it, but didn't have the time to attempt so.

I actually did use powdered KOH for this run, I used a mortar and pestle and the KOH flakes. The KOH being powdered didn't seem to change the reaction much if at all.

Squall181 - 4-8-2013 at 11:00

I just want to mention that before having a successful run I attempted using various magnesium sources and solvents.

In the first attempts, I used magnesium that I got by drilling into a piece of magnesium alloy that was scavenged from a car's steering column. No potassium was formed during these runs.

Next I went out and bought a Coleman magnesium fire starter. I made several runs using this piece. I tried using drill shavings first with no success. I then decided to use a rough file to make finer particles. In one of these runs I believe some potassium was made because upon disposal of the reaction mixture into isopropanol the alcohol caught fire, but there were no visible shiny balls.

I finally decided to invest in some magnesium from gallium source seeing that I spent way to much on that fire starter for nothing.

The first attempt using the gallium source magnesium was done by adding the t-butanol mixed with solvent a little at a time, using a hypodermic needle through the rubber stopper, no visible potassium was seen to form in this run, but there was much fizzing and flame when the reaction sand was poured into isopropanol.

The very next run was done exactly the same way as above except that all of the reagents were introduced at the beginning and the flask was not opened until it cooled down.

I plan on trying to use larger particle size of the purer magnesium and see if that still yields potassium, because it is a real pain to file enough Mg for just a small run.

blogfast25 - 4-8-2013 at 11:58

Thanks again Bob and Squall: it's those types of descriptions we need if we are to construct a better map of what works and what doesn't and what seems relevant and what doesn't appear to be.

Squall181 - 19-8-2013 at 16:33

So, now that I've become one of the members here who has successfully made potassium a question comes to mind, what is everyone doing with the stuff besides throwing it in water and saving it for an element collection. Is anyone using potassium in any interesting experiments?

I have recently been introduced to intercalated graphite compounds, and have made some potassium intercalated graphite as can be seen in the picture below.

I believe that the compound I was able to synthesis based on the color, is stage one potassium graphite with the chemical formula KC8.

I would like to synthesis stage 2, which should be a nice blue color with a chemical formula of KC24. But that has a few challenges of its own.

Just wanted to share my interests and I would love to hear from other members.

On a side note my previous post said that I used 30ml of solvent in the reaction, actually when I repeated my experiment using 30ml I was not able to get any potassium. So I reduced the amount to 20ml and have been making potassium successfully ever since.

I believe using just a little more than enough solvent to cover the reactants gives the best results.

Also I have found what I think is an easier way to make magnesium shavings for the reaction. I found this circular rasp tool at home depot and put into my drill press. By carefully running the magnesium ingot across the turning rasp very nice magnesium fillings are produced and work great in the synthesis.

http://www.homedepot.com/p/Vermont-American-5-8-in-Rasp-File...

bfesser - 19-8-2013 at 17:23

I hope you're planning a write up of that intercalate synthesis. I, for one, would love to read about it. I have a book on <a href="http://en.wikipedia.org/wiki/Intercalation_(chemistry)" target="_blank">intercalation</a> <img src="../scipics/_wiki.png" /> chemistry, but haven't been motivated to read through it yet.

[edit] Just looked it up on <a href="http://books.google.com/books?id=qrFVZwdVrVgC&printsec=frontcover#v=onepage&q&f=false" target="_blank">Google Books</a> <img src="../scipics/_ext.png" />.

[Edited on 20.8.13 by bfesser]

froot - 20-8-2013 at 02:20

Quote:

I believe that the compound I was able to synthesis based on the color, is stage one potassium graphite with the chemical formula KC8.

If I had that I'd try make my own K-ion cell.

Would love to see how you produced this.

[Edited on 20-8-2013 by froot]

blogfast25 - 20-8-2013 at 05:18

Yep, me too.

Squall181 - 21-8-2013 at 16:50

Well this may come as a surprise but it wasn't all that intricate of a synthesis.

Here are some references that I used:

http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1094&...

http://thesis.library.caltech.edu/5574/4/Purewal_Thesis_Ch2....

When attempting the synthesis the goal was actually to make the stage 2 compound and not the stage one, but if you read the two papers they mention that in order to obtain the stage 2 version of the compound the reaction mixture must be periodically stirred.

At the time I didn't exactly understand why this was important but it became quite clear soon after I began the synthesis.

So what I did was take 0.08 grams of K and put it into a vial with about .6 or so grams of graphite, (sorry I don't have the exact amounts in front of me at the time, but the amounts were just scaled from the purdue link)

Next I put the vial with the cap loosely fastened into the antechamber of my lab groups glove box (at the University) and pulled a vacuum. I then refilled the antechamber with argon and this was repeated 3times to get any air out of the vial. I then took the vial into the glovebox and screwed the cap on tight.

I am not a regular user of the glovebox so I did not want to do any heating of the material inside of it. So, I took the sealed vial out, which now contained argon inside and placed it into a muffle furnace and set the temperature to 150 degrees C. I left the vial at temperature overnight.

The next day I could see that a clump of something had formed inside of the vial but the majority of the graphite had not reacted. The vial was put back in to the glove box and the clump was separated from the rest of the graphite. Crushing the lump with a glass rod revealed the nice bronze color that can be seen in the above picture. This powder was sealed in a new vial and taken out of the glovebox.

Hope that wasn't too boring. I was going to try this at my home lab, but my vacuum pump is dead at the moment.

I would love to hear other people's ideas on how this can be done without a glovebox.

I still have not exposed the sample to air so I do not know exactly how it reacts, but I may try that this weekend just to see how sensitive the compound is.

blogfast25 - 23-8-2013 at 04:40

Quite interesting. This compound finds uses as?

elementcollector1 - 24-8-2013 at 16:14

Quote: Originally posted by blogfast25

Quite interesting. This compound finds uses as?

As far as Wiki tells me, it may replace Li-ion batteries in the future. I find that makes no sense, as from the same source, it shows all the reactivity of normal K metal - why on Earth would you put it in a battery?

blogfast25 - 24-8-2013 at 16:44

EC1:

Fair point but Li is also used in Li metal batteries: that metal reactivity isn't hard to contain.

Toluene - 16-10-2013 at 05:23

Hi!, I haven't been here for a long, and back to the work, I thought, that might be a good idea to try to catalize with diacetone alcohol, wich may be very simple preparated with acetone and a strong base such as KOH or NaOH, I will try and I'll give you a result!

sbbspartan - 2-11-2013 at 13:34

I just had something really interesting happen!

I've tried to do this synthesis 4 or 5 times now, and the last time I tried, I finally succeeded in making some potassium. However, it was only a bunch of very fine particles that I was unable to coalesce. I was going to post a writeup of my results on here, but I wanted to try it once more to see if I could get some larger balls of potassium first.

So, on this most recent attempt, I had 4.8 grams of magnesium (1/2 powdered and 1/2 turnings), 10 grams of potassium hydroxide, and about 35 ml of highly pure paraffin oil (Tiki Torch Fuel). I also added all of the tertiary butyl alcohol - about 2ml - right away since that was how I did it the last time I got potassium (unlike all the other times I added it a little bit at a time and never got potassium). I started the synthesis like normal, heating it up to 200+ Celcius.

Now, I normally get quite a bit of that weird white smoke coming out of the solution as it heats up, but this time was different. There was A LOT of it this time. After about 5 minutes on the hotplate, I started seeing a few fairly large sparks in the flask. I got a bit afraid at this point, so I turned off the hotplate. All of a sudden, the whole bottom of the flask lit up quite brightly - but not white light like magnesium burning, more of an orange flame. There wasn't really a flame though, sort of like something burning without oxygen. After about 5 seconds, the burning completely stopped, and my flask and condenser were covered in black soot.

My thought was that I must have heated it up too quickly or something, and the magnesium on the bottom of the flask got too hot and started to burn. However, it got even weirder. I let the flask cool down for a while and then looked in the bottom part that wasn't covered in soot. There were tiny little balls of potassium floating around. I might be mistaken, and it could have been magnesium powder, but they were floating, very bright/shiny, and I'm pretty positive they weren't there before. I dumped the contents out in my sink, and poured some water on it (I didn't really realize at the time that there was potassium in it). When the water hit it, there were tiny little sparks everywhere. It looked exactly like when I added some water to the potassium I got in my last synthesis.

I'm not sure what else it could have been besides potassium... But the flask was only on the hotplate for 5-10 minutes. Am I just going crazy?

It took 3-4 hours before I saw potassium last time. Maybe it was actually magnesium that caught on fire in my flask, and it was hot enough to accelerate the process...? I'm not sure.

elementcollector1 - 2-11-2013 at 15:09

Quote: Originally posted by sbbspartan

I just had something really interesting happen!

I've tried to do this synthesis 4 or 5 times now, and the last time I tried, I finally succeeded in making some potassium. However, it was only a bunch of very fine particles that I was unable to coalesce. I was going to post a writeup of my results on here, but I wanted to try it once more to see if I could get some larger balls of potassium first.

So, on this most recent attempt, I had 4.8 grams of magnesium (1/2 powdered and 1/2 turnings), 10 grams of potassium hydroxide, and about 35 ml of highly pure paraffin oil (Tiki Torch Fuel). I also added all of the tertiary butyl alcohol - about 2ml - right away since that was how I did it the last time I got potassium (unlike all the other times I added it a little bit at a time and never got potassium). I started the synthesis like normal, heating it up to 200+ Celcius.

Now, I normally get quite a bit of that weird white smoke coming out of the solution as it heats up, but this time was different. There was A LOT of it this time. After about 5 minutes on the hotplate, I started seeing a few fairly large sparks in the flask. I got a bit afraid at this point, so I turned off the hotplate. All of a sudden, the whole bottom of the flask lit up quite brightly - but not white light like magnesium burning, more of an orange flame. There wasn't really a flame though, sort of like something burning without oxygen. After about 5 seconds, the burning completely stopped, and my flask and condenser were covered in black soot.

My thought was that I must have heated it up too quickly or something, and the magnesium on the bottom of the flask got too hot and started to burn. However, it got even weirder. I let the flask cool down for a while and then looked in the bottom part that wasn't covered in soot. There were tiny little balls of potassium floating around. I might be mistaken, and it could have been magnesium powder, but they were floating, very bright/shiny, and I'm pretty positive they weren't there before. I dumped the contents out in my sink, and poured some water on it (I didn't really realize at the time that there was potassium in it). When the water hit it, there were tiny little sparks everywhere. It looked exactly like when I added some water to the potassium I got in my last synthesis.

I'm not sure what else it could have been besides potassium... But the flask was only on the hotplate for 5-10 minutes. Am I just going crazy?

It took 3-4 hours before I saw potassium last time. Maybe it was actually magnesium that caught on fire in my flask, and it was hot enough to accelerate the process...? I'm not sure.

Curious... But magnesium can also react with water at elevated temperatures - it's not out of the question.

sbbspartan - 2-11-2013 at 18:58

Quote: Originally posted by elementcollector1

Curious... But magnesium can also react with water at elevated temperatures - it's not out of the question.

Yeah, it was really weird. Thats never happened in all the times I've tried this experiment. I agree that the magnesium explains the sparks and the fire I saw pretty well. A hot spot could have formed on the bottom of the flask and gotten hot enough to ignite the magnesium.

However, I did let the flask and its contents completely cool down to room temperature before I dumped it into the sink. I don't know how the magnesium could have reacted with the water and produced those sparks in the sink when it was cold.

I'm not sure I could reproduce what happened, and I'm not really sure I want to anyway. I'll try the synthesis again tomorrow with slower heating and better stirring. I have to go clean out my blackened glassware now...

Pyro - 5-11-2013 at 14:00

I just obtained a gallon of 2-Ethylhexyl 7-oxabicyclo(4.1.0)heptane-3-carboxylate, it's density is even greater than tetralin. Is this a good solvent?
I intend to run this reaction tomorrow, but would like some opinions on the solvent first.
and tossing in a stirbar to keep it mixed?

[Edited on 5-11-2013 by Pyro]

Lambda-Eyde - 5-11-2013 at 19:56

Quote: Originally posted by Pyro

I just obtained a gallon of 2-Ethylhexyl 7-oxabicyclo(4.1.0)heptane-3-carboxylate, it's density is even greater than tetralin. Is this a good solvent?

For making potassium? No. Not at all. And where the heck did you get that, and what is it used for? Plasticizer?

Pyro - 5-11-2013 at 23:13

a gallon of model jet hydraulic fluid, I found it lying around. why exactly won't it work?

[Edited on 6-11-2013 by Pyro]

Lambda-Eyde - 6-11-2013 at 08:55

If you look at its structure, you should be able to identify two functional groups that won't behave nicely in the presence of potassium metal.

Squall181 - 10-11-2013 at 21:05

I didn't want to start a new thread and figured this would be a good place to ask and feel out any interests.

Is it possible to use potassium as a reducing agent to obtain other metals?
I've read about the Reike metal synthesis which yields highly reactive metals, but have not been able to find any detailed procedures or documentation. Could one use this method to make sodium for example? Why must the reaction be in tetrahydrofuran (THF) can other solvents be used? More information on this topic would be great.

Another method I've come across is the Hunter process that uses molten sodium to reduce titanium tetrachloride, could potassium be used in a similar fashion and with other metals besides titanium.

I have not been able to come across much information about using alkali metals as reducing agents, perhaps it's because it's impractical or impossible, but if it's the former than that shouldn't stop us from pursuing this idea, since we can make potassium quite readily these days.

Galinstan - 23-11-2013 at 10:23

yes it is possible to reduce other less reactive metal ions to there cosponsoring metals using potassium, but for reducing things with alkali metals your better off using Li as it's a better reducing agent than K and it's far easier to get hold of

blogfast25 - 24-11-2013 at 09:56

Here we go again with the use of vague and pretty meaningless terms and ‘explanations’ that resemble old wives tales more than actual science.

Whether or not a particular chemical reaction (here a redox reaction) can proceed or not depends on a number of factors and cannot be summarised easily in a few sentences. It is not simply a matter of ‘reactivity’ or the half potentials series.

For reactions where no reaction products can leave the reaction mix, the change in Gibbs Free Energy ΔG (= G2 - G1) must be smaller than zero for the reaction to be able to proceed. Even then the reaction might need heating to allow it to start and sustain.

This can lead to seemingly ‘contradictory’ situations. For example, NaOH can be reduced by Al: NaOH + 2/3 Al == > Na + 1/3 Al2O3 + ½ H2 because ΔG < 0 (to be fair, hydrogen does leave the mix here)

But Na can also reduce AlCl3: AlCl3 + 3 Na == > Al + 3 NaCl, because ΔG < 0.

So which is the ‘best’ reducing agent here, Na or Al? It’s a meaningless question.

The Rieke metal preparations proceed simply because ΔG < 0. It so happens that THF is a suitable, aprotic solvent as a reaction medium.

In processes where one of the reaction products can be removed from the reaction mix, seemingly unlikely reactions become totally possible. Cs can be prepared from CsCl by reduction with Li, K or Ca:

CsCl + Li < === > Cs + LiCl at high temperature and under high vacuum, because the Cs metal then distils off, leaving the non-volatile CsCl, Li and LiCl behind.

Re. the availability of Li over K, that such a subjective matter it isn’t even worth squabbling about.

Quote: Originally posted by Squall181

Another method I've come across is the Hunter process that uses molten sodium to reduce titanium tetrachloride, could potassium be used in a similar fashion and with other metals besides titanium.

Today the Kroll process uses Mg to reduce TiCl4. But 'Tetra' as it is fondly known in the industry is very hard to home produce and the reduction reaction requires pressurised vessels because of reaction heat generation and the volatility of TiCl4.

[Edited on 24-11-2013 by blogfast25]

Galinstan - 24-11-2013 at 11:36

When calculating gibbs free energy change temperature is already taken in to account so a reaction with G<0 will not require heating to happen but might require a change of temperature to achieve a measurable rate.

blogfast25 - 25-11-2013 at 05:58

Quote: Originally posted by Galinstan

When calculating gibbs free energy change temperature is already taken in to account so a reaction with G<0 will not require heating to happen but might require a change of temperature to achieve a measurable rate.

You are completely and plainly wrong.

Reactions that have strong negative Delta G are plenty, yet most don't proceed without heating. Examples: carbon + oxygen, butane + oxygen, nearly all thermites.

By your account the world would be a constant fireball, with all these spontaneous combustions happening!

You want to read up on 'collision theory' and 'Arrhenius equation'. Most reactions with negative Delta G still have kinetic obstacles to overcome: they are the rule, not the exception.

The reaction that is the subject of this long thread is another point in case: at RT nothing happens.

[Edited on 25-11-2013 by blogfast25]

Galinstan - 25-11-2013 at 06:43

You are correct just because a reaction has a negative Gibbs free energy change doesn't mean an OBSERVABLE reaction happens because the value of delta G is not proportionate to rate, so even though the reaction is thermodynamically favourable the rate might be so slow it appears as if no reaction at all is happening. and doesn't your example of thermites have more to do with surface contact than activation energy.

blogfast25 - 25-11-2013 at 12:31

Quote: Originally posted by Galinstan

and doesn't your example of thermites have more to do with surface contact than activation energy.

In a sense, yes. But at RT the collisions between the reactant species are by far not energetic enough to be reactive (as opposed to merely elastic).

Thermodynamics (considerations of Free Energy) and Kinetics (considerations of mechanisms and rates) are two very different things and should not be conflated.

elementcollector1 - 23-12-2013 at 17:34

I've noticed over the past few months that there is a curious brown 'fluff' floating alongside my potassium in it's kerosene-filled vial. The stuff seems to accumulate with time, and forms a colloid when shaken, discoloring the solvent to yellow-brown where it would normally be clear. This does not look like the brown potassium oxide I have dealt with before, and it may be some alkoxide, as I sometimes add a small amount of alcohol to the vial to keep the potassium shiny. Is this fluffy stuff a problem? The potassium metal itself is about the same size, and as shiny as ever.

Zyklon-A - 23-12-2013 at 19:37

Impurities in the kerosene maybe.

blogfast25 - 24-12-2013 at 05:42

EC1:

I don't know but one thing is for sure: potassium is not meant to be kept under oil/paraffin/kerosene forever. Only properly glass ampouled material can be kept 'indefinitely'. Oiled alkali metals are meant to be used, not just put on display.

alexleyenda - 15-6-2014 at 11:28

I'll attempt this famous reaction soon, probably before the end of the week. Since then, I just wanted to share that the legendary Nurdrage's video isn't exactly gone

http://v.youku.com/v_show/id_XNTAxODAzMTc2.html

Burner - 15-6-2014 at 12:07

Quote: Originally posted by alexleyenda

I'll attempt this famous reaction soon, probably before the end of the week. Since then, I just wanted to share that the legendary Nurdrage's video isn't exactly gone

http://v.youku.com/v_show/id_XNTAxODAzMTc2.html

But unfortunately it is only a piece of the video.

Anyone have the links to the rest of it? Thanks!

alexleyenda - 15-6-2014 at 14:44

Really, it was longer than 10 mins? Anyways, all the essential informations are there I think.

Zyklon-A - 15-6-2014 at 18:02

Quote: Originally posted by alexleyenda

I'll attempt this famous reaction soon, probably before the end of the week. Since then, I just wanted to share that the legendary Nurdrage's video isn't exactly gone

http://v.youku.com/v_show/id_XNTAxODAzMTc2.html

Thanks! I've been looking for that for a while.

Brain&Force - 30-6-2014 at 21:10

Quote: Originally posted by alexleyenda

I just wanted to share that the legendary Nurdrage's video isn't exactly gone

The legendary NurdRage isn't exactly gone, either:

<iframe sandbox width="560" height="315" src="//www.youtube.com/embed/gw9ZzvSiyAQ" frameborder="0" allowfullscreen></iframe>

And neither is his potassium video:

<iframe sandbox width="560" height="315" src="//www.youtube.com/embed/JAo2F9ymKXA" frameborder="0" allowfullscreen></iframe>

Pyro - 2-8-2014 at 22:16

i looked though the previous pages and found no evidence that anybody ever tried adding a tiny bit of I2 to activate the magnesium.
This would make sense as it's used to activate Mg for many other uses (grignard, drying EtOH,...)

elementcollector1 - 3-8-2014 at 07:58

That is an interesting idea - if I still had any t-BuOH, I'd certainly try it.

Pyro - 3-8-2014 at 10:08

so would I but my lab is currently in boxes.

vigorous stirring with a magnetic stir bar will probably help the reaction along very well, coalescing the K as well as providing lots more surface area for the reaction.

blogfast25 - 3-8-2014 at 12:57

I2 isn't necessary if your magnesium is sufficiently blank. The way it initiates Grignards is quite different from what it can do here: a small amount of I2 will only 'clean' a small amount of Mg.

As regards the role of stirring, it's far from clear judging by the many attempts described in the thread. The boiling of the solvent seems to provide enough agitation for most people's purposes, it did for me. A very early attempt by 'len1' using high speed stirring in fact failed completely to produce any potassium.

Mailinmypocket - 3-8-2014 at 13:17

I still intend to try this experiment, the only thing I need to do is buy some quality Mg powder which I have still not got around to doing(I would buy tetralin also but that almost feels like cheating, the idea is to make it simple for everyone!) . If I can make it work without I2 then I'll try I2 with the other grades of Mg and see if something happens. Right now I can't be bothered since I already have commercial K anyways. Still a fascinating project to try though!

[Edited on 3-8-2014 by Mailinmypocket]

Pyro - 3-8-2014 at 18:43

@blogfast25: that is also all that is necessary to activate it.

blogfast25 - 4-8-2014 at 12:23

Quote: Originally posted by Pyro

@blogfast25: that is also all that is necessary to activate it.

The difference is that in Grignards that practice is fairly proven where as here we really have no idea.

Here the first port of call is to try a 'good grade' of Mg and try it as such.

gdflp - 25-11-2014 at 11:01

How would propylene carbonate work as an alternative "solvent" for the reaction instead of tetralin? It isn't significantly cheaper to buy, but it is much easier and cheaper to make and it is also denser than potassium like tetralin.

Zyklon-A - 25-11-2014 at 11:18

I don't see propylene carbonate mentioned in the last few pages of this thread. Did you mean to post in this one?

[EDIT] it's not used as a solvent, but rather a non-reactive electrolytic solution, used to plate out metals that would otherwise react with common solutions, like water.

[Edited on 25-11-2014 by Zyklon-A]

gdflp - 25-11-2014 at 11:39

No, I meant as a replacement for tetralin in the magnesium, tertiary alcohol cat. method. If it can be used for electrolysis it obviously isn't reactive towards potassium, it has a high boiling point at 242°C to allow the reaction to reflux, are there any other things I'm missing which will cause it to not work in that method.

blogfast25 - 30-11-2014 at 09:51

Quote: Originally posted by gdflp

No, I meant as a replacement for tetralin in the magnesium, tertiary alcohol cat. method. If it can be used for electrolysis it obviously isn't reactive towards potassium, it has a high boiling point at 242°C to allow the reaction to reflux, are there any other things I'm missing which will cause it to not work in that method.

It would be worth trying that but I have concerns about its reactivity towards KOH and the alcohol catalyst at these temperatures. Also Mg will have a tendency to snatch the abundant oxygen.

This resource gives some indications on the chemical resistance of polypropylene carbonate to various chemicals:

http://www.engineeringtoolbox.com/polypropylene-pp-chemical-...

But 200 C is a long way off 60 C!

[Edited on 30-11-2014 by blogfast25]

Metacelsus - 30-11-2014 at 11:11

Yes, it's an ester, which means that it is probably unstable in the presence of KOH (saponification will take place).

Zyklon-A - 2-12-2014 at 12:55

blogfast25, I'm confused by your link. You say it's for polypropylene carbonate, but the link is for polypropylene, a hydrocarbon thermoplastic polymer, containing no oxygen (hence hydrocarbon).
Is there something I'm missing?

blogfast25 - 28-12-2014 at 08:45

Yes, it's not for propylene carbonate. My bad.

gdflp - 6-1-2015 at 09:37

No, we're talking about the solvent for the reaction. If t-Butanol was used, the reaction temperature would remain at the boiling point of t-Butanol, 82°C. The reaction needs to be around 200°C for the required intermediates to form. t-Butanol is used in the patent, but it is used as a catalyst rather than a solvent.

blogfast25 - 28-1-2015 at 13:08

Quote: Originally posted by tibow64

I think that a more non-polar alcohol such as t-butanol would give superior results as in the patent.

More t-butanol than KOH would simply result in all K being present as K t-butanoate. Period.

S.C. Wack - 28-1-2015 at 13:16

No point arguing with Spammer With New Tricks tibow64.

blogfast25 - 28-1-2015 at 13:27

Quote: Originally posted by S.C. Wack

No point arguing with Spammer With New Tricks tibow64.

Sorry, didn't realise he was a spammer.

maleic - 5-2-2015 at 19:48

It's really cool! And the commentary also great!
I hope this is true and feasible.

Blunotte - 2-4-2015 at 22:45

Hello, nobody tried this?

K2C4H4O6 --Heat--> K2CO3 + 2C + CO (^gas) + 2H2O (^gas) --Heat800°--> 2K (^gas) + 3 CO (^gas)

The potassium can be condensed in a metal tube in absence of air, and CO and H2O will escape as gas

[Edited on 3-4-2015 by Blunotte]

blogfast25 - 3-4-2015 at 05:48

Quote: Originally posted by Blunotte

Hello, nobody tried this?

K2C4H4O6 --Heat--> K2CO3 + 2C + CO (^gas) + 2H2O (^gas) --Heat800°--> 2K (^gas) + 3 CO (^gas)

The potassium can be condensed in a metal tube in absence of air, and CO and H2O will escape as gas

[Edited on 3-4-2015 by Blunotte]

What's "K2C4H4O6"?

Blunotte - 3-4-2015 at 08:12

Quote: Originally posted by blogfast25

What's "K2C4H4O6"?

Potassium tartrate (LINK to Wiki)

At about 400 ° C decomposes, and the result of the decomposition is in the correct stoichiometric ratio for the subsequent reaction, in addition to achieving the reagents perfectly mixed.

Both reactions should be carried out in a metal tube, closed at one end, and the other must be crushed so as to leave only a small flat opening.
The carbon monoxide burns in air, and the metallic potassium falls into a container filled with liquid paraffin.

Blunotte - 3-4-2015 at 08:19

procedure:
Take an iron tube of about 50 cm in length and 2 cm in diameter, close to one end, and the other end is crushed in a vice, to leave a small output.
Pour in the tube a few grams of potassium tartrate.
Place the tube horizontally above a barbecue switched on, with a beaker of paraffin oil under the exit.
Wait a little.
All Done.

j_sum1 - 3-4-2015 at 19:01

@ Blunotte
Try it and see. Report back. To my relatively untrained eye it seems vaguely like it might be feasible. It is a lot higher temperature than the process discussed here -- which, incidentally I attempted unsuccessfully. (I ill attempt again with cleaner, finer magnesium and a better grade of mineral oil.)
Higher temperature and gaseous metals seems like a combination that is likely to introduce unforeseen problems, but it might work.
Have you checked out the feasibility from a thermodynamic viewpoint?

Blunotte - 3-4-2015 at 19:49

@j_sum1

Many years ago, the potassium was prepared in this manner, at the industrial level.
I'm sure it works well.
What I don't know is if we can repeat the experiment in small, and make it in a home lab

My son is growing up, and I want to prepare a small home lab, so I do not know if we can do this experiment now, I think we need some time

blogfast25 - 7-4-2015 at 14:19

Quote: Originally posted by Blunotte

procedure:
Take an iron tube of about 50 cm in length and 2 cm in diameter, close to one end, and the other end is crushed in a vice, to leave a small output.
Pour in the tube a few grams of potassium tartrate.
Place the tube horizontally above a barbecue switched on, with a beaker of paraffin oil under the exit.
Wait a little.
All Done.

I’m sorry but this is complete nonsense. On strong heating potassium tartrate in all likelihood decomposes to potassium carbonate. The pyrolysis of potassium bitartrate to potassium carbonate (‘Pearl Ash’, if it came from ‘cream of tartar’) was once an industrial preparation of the latter. At very high temperature K2CO3 will partially decompose to K2O but not to elemental potassium.

No potassium without a reducing agent or electrolysis.

Blunotte - 8-4-2015 at 11:30

Quote: Originally posted by blogfast25

Please read what I wrote before:

K2C4H4O6 --Heat--> K2CO3 + 2C + CO (^gas) + 2H2O (^gas) --Heat800°--> 2K (^gas) + 3 CO (^gas)

At first time, CO and H2O will be produced and escapes as gas.
In a second time, K2CO3 + 2C -> 2K + 3CO

Potassium carbonate + carbon --StrongHeat--> Carbon monoxide (escape as gas) + metallic potassium as vapor.
Potassium condensate as liquid in the tube and fall in a cup with liquid paraffine.

Stop

blogfast25 - 8-4-2015 at 12:29

Blunotte:

If you have some credible references to that process, I'd like to see them. Until then, I remain sceptical. At the very least it would require vacuum, as in the case of the carbothermic reduction of magnesia.

This below does reference a process for carbothermic reduction of soda and potash:

Quote:

The rst recognized production of sodium and potassium metalswas by Sir Humphrey Davey. In November 1807, Davey announced the discovery of sodium and potassium metals which he had been able to produce by electrolysis of potassium or sodium salts. Shortly after Daveys announcement, Gay-Lussac and Thenard announced to the Institute of Science in Paris that they had decomposed potash and soda by treating them with iron at a high temperature. A few weeks later, in the spring of i808, Curaudau told the Institute of Science that he had succeeded in metallizing potash and sodium by strongly heating them with charcoal. The Curaudau process was further developed by Deville in France into a commercial process and for a large number of years was the principal `source of sodium metal. Devilles method produced all the sodium that was needed for the production of aluminum (which was the principal market for sodium) until the sodium industry was upset by the introduction of the Hall electrolytic process for the preparation of aluminum in the last ten years of the 19th century.

http://www.google.co.uk/patents/US2930689

[Edited on 8-4-2015 by blogfast25]

Polverone - 8-4-2015 at 15:19

There is a good description of the process here: https://archive.org/stream/ldpd_10922488_002#page/746/mode/2...

The process was tedious, low-yielding, hard on equipment, energy intensive, and hazardous. But it was practiced industrially for decades.

blogfast25 - 8-4-2015 at 15:43

Quote: Originally posted by Polverone

There is a good description of the process here: https://archive.org/stream/ldpd_10922488_002#page/746/mode/2...

The process was tedious, low-yielding, hard on equipment, energy intensive, and hazardous. But it was practiced industrially for decades.

Thank you, Polverone. I managed to find some information earlier on tonight but it's amazing how many processes seem to get 'forgotten' when they get into disuse. Most modern sources don't mention this historical process anymore.

This JSTOR page provides some description too:

http://archive.org/stream/jstor-30073580/30073580_djvu.txt

Blunotte - 8-4-2015 at 19:52

Quote: Originally posted by Polverone

Thank you, Polverone.

I hate when people do not believe me :mad:

About 25 or 30 years ago, I had a book where the preparation was accurately described, and there were also some images.
Now unfortunately I can not find this book, and I can not prove anything.

But in your library, there is still a book in which he speaks of this preparation:
A Text-Book of Inorganic Chemistry Volume II: The Alkali-Metals and Their Congeners (A. Jamieson Walker, edited by J. Newton Friend), page 152.
(just few rows, but...)

I know, the preparation has a low yield, is not elegant, it needs high temperatures...
But it has very low costs: the potassium tartrate (or its acid tartrate) is cheap (here in Europe we use it for stabilization of wines, only few euro for a kilo), and you do not need expensive equipment, just an iron pipe and a brazier with coal

Ok, it's enough, I seem to fight the windmills, if someone wants to try, well. For me, I'll try to do the preparation when my son will be older (he is only 7 years old, now)

Have a nice day

[Edited on 9-4-2015 by Blunotte]

blogfast25 - 9-4-2015 at 06:28

Quote: Originally posted by Blunotte

I hate when people do not believe me :mad:

About 25 or 30 years ago, I had a book where the preparation was accurately described, and there were also some images.
Now unfortunately I can not find this book, and I can not prove anything.

Scepticism is part of science. No need to get mad about that.

Polverone's reference puts the matter to rest. It also mentions potassium tartrate (Argol) as a source of potash/carbon for carbothermic reduction of potassium metal.

But read the relevant section of that ebook: the method is hardly as easy as you describe it. One reported yield was only about 50 %. Modern adaptations, perhaps using argon flux, could possibly improve it a lot and make it safer. I'll put it on my 'bucket list'.

APO - 27-4-2015 at 21:25

It looks like the original thread for potassium production on versuchschemie doesn't exist anymore!?!

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