Making Manganese Metal

I synthesise a small quantity of manganese metal from manganese sulfate by electrolysis.
Despite the simplicity of the idea, generating manganese metal through aqueous electrolysis has a few barriers, mainly the fact that the reduction potential of manganese is much lower than that for water, and thus the electrolysis process will always favour the production of hydrogen over manganese.
To get around this, we set up a divided cell to electrolyse our manganese salt, and succeed in making a small amount of metal over the course of 24 hours.

[mildlyacidic]

This beats the thermite process by a long shot. No need for hazardous molten metal and separating slag. Thanks for sharing, big fan of your projects.

[anti-fzbe]

PS. Important!
If you want to directly make a Mn/Graphite electrode, you need TO SPIN THE ROD! I mean, you use your old setup, and connect the electrode to a motor using a rubber tube. Use some copper wire as brush. This will make a better coat.

[Clipster]

I remember back a few years ago when I was getting into a little chemistry to make iron oxide for a thermite reaction (which failed because of non-existing knowledge.) I tried to make the iron oxide via electrolysis with iron nails for the anode and thought aluminum would be good for the cathode. Nope. Aluminum is corrosion resistant, right? I thought (ironic because how do think the thermite reaction takes place...?) I came back the next day and it was gone with white stuff laying on top of my iron compound precipitates. I was able to separate it, mostly, and get my iron precipitates. Now I know aluminum (metal) is actually quite reactive and through this the formed passivation layer (of which is quite stable) protects it, at least in bulk. Now I believe I know why it went terribly wrong. The aluminum passivation layer was broken in the alkali region of the cathode being plentiful of OH-, and aluminum being reactive, oxidized to Al3+, reducing hydrogen, and forming Al(OH)3, my white precipitate. My thermite failed probably because what I thought I had being iron III oxide was probably iron oxyhydroxide (I didn't heat the cleaned precipitate enough to decompose it.) Oh well, funny to look back on though. I did about a month ago use some quite fine aluminum powder I made to make a small amount of thermite. Good thing it was a small amount. Fine aluminum makes more for an explosion than a pretty shower of molten iron. :)

[johnslugger]

If you smash it with a hammer or hydro press it will turn silver.

[bedlaskybedla]

Very interesting. I read one paper about electrolytic Mn production years ago. They used stainless steel cathode, in anode cell ammonium sulfate solution and in cathode cell manganese sulfate + ammonium sulfate solution. Ammonium ions are weakly acidic, they react with any OH- produced forming ammonia, so this basically solves the problem with manganese hydroxide formation.

[Telectronics]

Another cool video series of electrolysis and it´s value ! Thanks for your effort mate :)

[FullModernAlchemist]

Cool video dude! I can’t believe I haven’t seen your channel yet. Awesome stuff. Im glad you’re here.

[coffeecuppepsi]

Can you do a video explaining the voltages (reduction/production potential) you talk about

[Prchemist]

Will reaction of manganese sulfate with aluminium strip produce manganese metal and aluminium sulphate ?

[JohnLeePettimoreIII]

i always smile when someone pronounces it "al-yoo-minium".

[zaneenaz]

according to your table graphite and aluminum have similar H2 overpotentials ! curious why you had to use 9.8v ....resistance? current required?

[omsingharjit]

7:30 you aluminium foil make may be coated by tin layer and ever after that Aluminium is very reactive in water which forms Hydroxide so why you choose Aluminium ?

[pessimistic]

question how much tablespoon or cup of salt adds / or makes water a pound heavier

because i know that a gallon of water weights like 8 pounds so id would like to know how much salt do i need to add to make it more heavy

[ceasargaming]

I might be misunderstanding something here...but how would manganese II ions be oxidized by the anode? Isnt it a cation?

[bpark]

Regarding cathode conditions, isn't material selection issue moot as soon as the Mn is deposited, the reaction's conditions will be that of Mn metal regardless what material we start with?
Regarding overvoltage, this should not be issue as iron, zinc (electro-galvanizing routinely done on iron in industry), & even aluminum can be electroplated in aqueous solutions.

[TristanLaguz]

Great video 👍! A nice and clean way to get manganesium (yup, that’s how it was upspringly called ;)) metal. Useful, too, since one can make potassium permanganate from Mn metal, as you’ve shown in another great video of yours. I’d like to ask a few questions:

1) It’s true that hydrogen’s reduction potential is lower the higher the pH is, but the same is true of that of manganese. The CRC Handbook of Chemistry and Physics lists the redox potential of Mn2+ + 2 e → Mn as –1.185 V (same as in your video) and the redox potential of Mn(OH)2 + 2 e → Mn + 2 OH– as –1.56 V. That source also says that the half-reaction 2 H2O + 2 e → H2 + 2 OH– has a redox potential of –0.8277 V (same as in your video), though. Hence, a higher pH seems to lower the reduction potential of H2 more than that of Mn, so you’re right that a higher pH is more favorable to the formation of Mn. Is that right?

2) Why is the anolyte made of sulfuric acid? Don’t the H+ ions diffuse through the diaphragm separator into the catholyte and make it sour, contrary to what we want (after all, they’re by far the smallest of all ions)? Shouldn’t we therefore use a neutral anolyte instead, e.g. watery NaCl solution?

3) Could it be that expoiting the high activation overpotential of aluminum didn’t work because it makes the reduction potential of manganese more negative as well as that of hydrogen?

4) It’s true that the reduction potential of Mn is lower than that of H2, but so is Zn’s; yet zinc can be won from a watery ZnI2 solution without any problems, so why shouldn’t the same be true of manganese in principle (I write ‘in principle’ since Mn is more negative than Zn)? To me, it seems that when electrolysing a neutral or alkaline watery solution of a metal salt, the main first product at the cathode really is the elemental metal, but when the metal is very electropositive (e.g. Na, Mg, or Al), it immediately reacts further with the water to give hydrogen and again the metal ions. This looks logical to me because in a neutral or alkaline aqueous solution of a metal salt, there are many more metal cations than hydrogen cations, so the lion’s share of the ions which are attracted to the cathode and are reduced there should be made up of metal cations, not H+ ions. This hypothesis of mine is corroborated by the deedsake (fact) that metals that don’t react vigorously with water at once, such as Cu, Fe, Mn, and Zn, can be gotten from an aqueous solution by electrolysis, whereas that isn’t possible for metals like Na, Mg and Al that react vigorously with water (Mg and Al do so when not protected by a passivating layer, which is very likely the case for nascent metal). Is this theory of mine and my explanation (sweotoling) right? If yes, then the quite negative reduction potential of Mn is no reason to worry; since Mn doesn’t vigorously reduce water, we can be optimistic.

[LucyOfAeonia]

Im probably being an idiot but how come you cant use 2 beakers and a salt bridge instead of the clay pot. Thereby allowing ion transfer but the liquids can never touch. I know there is something im missing which will make this obvious any help is greatly appreciated. I noticed in other videos you would have to add water continously to the clay pot as water diffused out of it into the larger solution. Genuinely just want to solve this conundrum in my brain

[lautaromorales]

¿Lead metal from the lead suphate and dioxide form car batteries can be recovered by this metod or a similar one? reacting it with nitric acid and then doing the electrolysis

[lioncub]

Nice video, thank you. Do you think this method can also be used to get cobalt metal from a cobalt salt? I have a bit of cobalt sulphate and more cobalt acetate in the shed.

[eldonjanzen]

Aluminum sheet? What about a aluminum coke can? Remove all the paint?