Sciencemadness Discussion Board

Magnesium Chloride to Magnesium Metal

TGT - 9-11-2014 at 18:35

Hello all! I am a new member here and this is my first post, but not my first time visiting. I have been lurking the forum for ages now and have always been annoyed of the fact I could not respond. So I thought it time to actually become a member and hopefully be useful here along with the ability to receive help from other similarly interested people. It seems this place is filled with knowledgeable users and in my opinion is the best place on the net for what interests me.

I have one small question that I cannot seem to find an answer for. I am interested in trying to create powdered magnesium metal with electrolysis. I have seen it done with many other chemicals, but never Magnesium Chloride. I am thinking to super saturate water with MgCl2 and use around 5 volts with 20 amps to electrolyse the solution and hopefully form Magnesium metal. It should already be in powdered form when filtered and usable when dry, or at least that is what I am hoping for.

I have done a previous experiment to get powdered silver by mixing water with Silver Nitrate and then placing copper in the solution to eventually get powdered silver. Although the reaction is different, I am hoping something similar to happen from the cathode or anode to develop a powdered metal.

So my question is, what material should be used for the cathode and anode when doing this experiment? Thank you all in advance and I am very happy to finally be a full member!

TGT

diddi - 9-11-2014 at 18:49

you cannot displace Mg2+ from water. see the redox potential table:

http://en.wikipedia.org/wiki/Standard_electrode_potential_(data_page)

you would need a melt to be able to use electrolysis
you will note on redox potential table that Cu and Ag are both below water, which explains why it is possible for production of Cu, Ag metals in this way.

TGT - 9-11-2014 at 19:04

Thank you for the info, I will read more about the redox potential and see what can be done. If I find something I can do, I will add to this thread. I was hoping I could start a new experiment and log it here, but now I might be dead in my tracks. lol.

TGT

j_sum1 - 9-11-2014 at 19:13

If you have the equipment to do electrolysis on a molten salt at over 714°C (and safely vent the Cl2) then you can proceed.
If not, then I'm afraid you really are dead in your tracks.

It's always nice to have a clear-cut situation though.

DraconicAcid - 9-11-2014 at 19:26

Quote: Originally posted by j_sum1  
If you have the equipment to do electrolysis on a molten salt at over 714°C (and safely vent the Cl2) then you can proceed.


You don't have to melt pure magnesium chloride, though- you could make a eutectic mixture of magnesium chloride, potassium chloride and sodium chloride, which melts at 475 oC.

http://www.sciencedirect.com/science/article/pii/00134686638...

j_sum1 - 9-11-2014 at 19:31

In the context of this discussion, I doubt it matters.
Anyway, won't the potassium reduce preferentially before the Mg? (I only ask because there is a huge sticky thread here where Mg is used to reduce KOH to K.)

Zyklon-A - 9-11-2014 at 21:06

Not with the chloride. KCl is more stable then MgCl2 but KOH is less stable then MgO or Mg(OH)2. Thus magnesium can reduce potassium oxide or hydroxide but not chloride. Same applies to sodium.

diddi - 10-11-2014 at 01:15

potassium has E° = -2.9
Mg =-2.3
Na = -2.7
so displacement order is Mg first, then Na, then K