Sciencemadness Discussion Board

How to store Magnesium turnings

Pyro - 28-5-2014 at 12:43

Hi,

I got 1kg of Mg turnings for Grignards, it came in a bag.
Before I open it I would like to know how I can best keep it without it oxidising because the volume is very big (30x50x10 cm bag)

ideas?

numos - 28-5-2014 at 13:55

Perhaps a desiccator with a vacuum? There always oil, but there's no way to easily use it after that... If you have ampules, that might be a thought.

[Edited on 5-28-2014 by numos]

HgDinis25 - 28-5-2014 at 14:03

You can flush a storage bottle (air tight, those used to store hygroscopic reagents) with Argon. Store the turnings in there. Every time you open it, a little bit of air may go in, so after a while you should flush the bottle again with argon. Not too much air will get in in each use because argon is denser than air. This may be a awkward way of storing it but it's better than having to go all the trouble storing it in a dessicator or using parafin.

Pyro - 28-5-2014 at 14:24

My main problem is the enormous volume, it's more than 5l

Dan Vizine - 28-5-2014 at 14:56

This isn't really much of an issue. Put it into glass bottles with non-permeable caps, just like the chemical companies do.

When the (already oxide coated, whether you see it or not) metal is used, a few iodine crystals will activate the surface.

Bert - 29-5-2014 at 07:45

If you're not going to open and close the container, there are commercial Oxygen absorbers. If you have any of the little chemical hand warmer packages made with Iron powder, charcoal & salt on hand- Same thing. Be warned: the bag will be similar in condition to a vacuum packed bag, it must be strong enough to resist punctures from sharp points of the contents. DO NOT use the absorbers in a glass bottle, it may implode.

If you're going to open & close frequently, Argon gas flush & fill as recommended above.

I have indeed seen Mg filings and ESPECIALLY Mg powder so oxidized in storage as to be useless.

Dan Vizine - 29-5-2014 at 17:45

This is a picture of magnesium turnings I've stored for 16 years in a HDPE Nalgene bottle under air. The bottle has been opened dozens of times. They are bright silver. This is high purity metal, purchased as a reagent for Gignard preps. You could reasonably expect similar results.



Mg.jpg - 118kB





[Edited on 30-5-2014 by Dan Vizine]

blogfast25 - 30-5-2014 at 10:11

Quote: Originally posted by Dan Vizine  
This is a picture of magnesium turnings I've stored for 16 years in a HDPE Nalgene bottle under air. The bottle has been opened dozens of times. They are bright silver. This is high purity metal, purchased as a reagent for Gignard preps. You could reasonably expect similar results.









[Edited on 30-5-2014 by Dan Vizine]


I'm much inclined to agree. I sell high quality, high mesh Mg powder. It's stored under air. I don't see it change at all. I don't use it for Grignards though...