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Make Potassium Metal

video Make Potassium Metal
We make potassium metal using a lesser known chemical approach of reduction with magnesium.

Warning: Making potassium is extremely dangerous. Full fire safety protocols must be in place including protective clothing, goggles and face shields. Burning potassium cannot be extinguished by conventional means and water only serves to increase its danger. This experiment should only be performed by an experienced chemist in a fume hood.


In a flask place 2.4g of magnesium turnings or powder, 5g of potassium hydroxide, and 20 mL of tetahydronapthalene or paraffin/mineral oil. If using oil the boiling point should be greater than 200 degrees Celsius.

Fit a reflux condenser onto the flask and prevent air access by covering the top of the condenser with foil. Alternatively a bubbler or a punctured balloon may be used.

Heat the reaction to reflux or +200 degrees Celsius. Color change of the solvent may occur at this time.

Inject of 0.4 mL of a tertiary alcohol (t-butanol and t-amyl alcohol have been confirmed successful) through the top of the condenser.

Add in an additional 0.1mL of alcohol every 10 minutes for a total of 0.6 mL of additional alcohol (1.0 mL overall).

Continue to reflux until potassium is produced. If potassium goes dark, add an additional 0.1 mL of alcohol.

What’s happening is the magnesium reacts with the potassium hydroxide to produce potassium metal, hydrogen gas and magnesium oxide. The alcohol catalyzes this reaction.

If you’re using a high-density solvent where the potassium spheres float, then coalescence of the spheres into larger spheres should occur automatically. If they are not, then an additional 0.1 mL shot of alcohol may be necessary. If using a lower density solvent, then coalescence may be achieved using this video: http://www.youtube.com/watch?v=xzkajgxVbyI


The reaction is done when there is no more magnesium. Turn off the heating and allow to cool.

Dump the cooled products into toluene and retrieve the metallic potassium, washing with additional toluene.

Place the potassium into a clean vial with mineral oil for short term storage.

All apparatus must be rendered safe before water-washing by first adding isopropanol to all containers that handled potassium. Any potassium residues should start bubbling. Only when bubbling has ceased can the wastes be disposed of as organic waste and containers subsequently washed with water.

DO NOT use water washing before alcohol washing as metallic potassium residues will ignite.

Additional Notes:

Alcohol *may* be added entirely at the beginning of the reaction but reproducibility is an issue since a competing reaction of alcohol decomposition sometimes occurs. It is difficult to predict how all reagents and solvent grades will behave so it is recommended to first attempt the experiment with staggered addition as outlined here.

A special note about long term storage safety. Do not leave potassium in storage for too long. Potassium forms shock sensitive explosive coatings on prolonged storage even under mineral oil. It is recommended that potassium be used or destroyed within a few months. If long-term storage is required then sealing in a glass ampoule or storage in an inert atmosphere glove box is recommended. Further information about the dangers can be found at: http://pubs.acs.org/doi/pdf/10.1021/ed085p634.2


Occasionally stirring the reaction (every 30-45 minutes) greatly improves reaction rate and yield. Remember to allow reaction to cool before removing the condenser.


The quality of magnesium is important for the reaction. Highly oxidized magnesium didn’t work to produce potassium. Buying new magnesium, or grinding it off from a magnesium ingot is recommended. Alternatively, low quality magnesium maybe activated by placing it into the solvent first without the potassium hydroxide and adding 0.1mL of alcohol and boiling for several minutes. The alcohol helps to etch the surface and restore activity. Note, this method is not absolutely reliable.

There have been reports of sodium being made by this method but I have never been able to successfully make it.
23 comments
Feb 19, 2012. 8:19 PMSpikeydude6392 says:
wow i love your video. perfect step by step if u have all said materials.
Jan 11, 2012. 1:45 PMjakobus9 says:
I have spend many hours trying to figure out how this could be done. (somehow an other solvent but water never came to mind long enough to consider it)
but can't the kinetics be improved? isn't there a catalyst which makes it a little bit faster,
no offense, but waiting hour(s) might seem like an eternity.
greetings
Feb 6, 2012. 6:29 AMjakobus9 says:
that indeed sounds a lot better :-)
thanks for the reply
Feb 2, 2012. 3:28 AMMekzoJoe says:
I want a Nurd Rage t-shirt. Could make it myself i guess but would rather pay you too fund all the great work.
Jan 24, 2012. 7:47 AMspinaci says:
I wonder if I could make Cs by this way
Jan 25, 2012. 7:55 PM9mag9 says:
If You do do not put the cesium in water. its a great way to lose some body parts.
Jan 27, 2012. 9:48 AMspinaci says:
Well, Cs could be ignited just in room temperature. Also Cs is too expensive for losing body parts
Jan 8, 2012. 9:13 AMmaxwelljets says:
Might it be possible to use a mixture of sodium and potassium hydroxides in this reaction to produce sodium? Wouldn't the potassium metal that's produced react with the sodium hydroxide present to produce sodium metal and potassium hydroxide? That way, you could produce a mixture of sodium and potassium.
Dec 31, 2011. 8:08 AMthrobscottle says:
Fascinating! But, questions:
Once you've got the potassium, what can you do with it?
How on earth do you work out how to do this - how you are going to make the reaction take place?
Jan 6, 2012. 12:20 PMNormReitzel says:
Nice video. In the US patent for this method, the sodium synth uses preformed sodium alcoholate. I'd like to suggest trying n-butanol or n-pentanol as the catalyst.

There is also a published synth using sodium in ethanol to reduce naphthalene to tetralin and then on to decalin. I've actually run this reaction, and yields are a lot higher using a neutral (decane) hydrocarbon with naphthalene dissolved in it, adding sodium, and reducing with ethanol.
Jan 2, 2012. 4:37 PMGASSYPOOTS says:
how u put it out i got a small fire in a container that has holes in it :O
Dec 31, 2011. 10:18 PMFlatLinerMEDIC says:
And this is what keeps HAZMAT so busy=)
Dec 31, 2011. 9:52 PMwespow1 says:
I love your laugh at 7:16 it's so funny.
Dec 31, 2011. 6:19 PMmrmerino says:
Well, alcohol does tend to make things coalesce.
Dec 31, 2011. 1:09 PMjarheadwithm16 says:
This is quite fascinating to watch ( like all of your videos) good job. Ever think of doing a video on making sodium through the electrolysis of molten sodium chloride?
Dec 31, 2011. 8:11 AMfrodobot says:
Hi,

I love these videos! But you can't click on the How to coalesce potassium video link because of the youtube bar coming up every time :/ Great video though :)
Dec 31, 2011. 12:12 PMfrodobot says:
Thats great, cheers :)
Dec 30, 2011. 12:51 PMmikeasaurus says:
My brain grows a little each time I watch one of your videos

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NurdRage is a dedicate group of science nerds trying to further amateur science with direct how-to instructions in video format. We saw what was already online and we thought "we could do better"... s...
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