ScienceGeek - 6-2-2008 at 04:16
I got a sealed metal container with a label that said: Aluminum Carbide.
I thought Al4C3 was a yellow to brown substance and reacted violently with water, producing methane gas.
When I opened the container, it contained a very fine, grey-brown powder and did not react with water whatsoever. The powder just "sticked" to the
water like a fine mesh aluminum powder.
Below is a picture of the powder:
Does anyone have any idea of what this is/what happened?
Any suggestions are appreciated 
not_important - 6-2-2008 at 07:15
Um, perhaps it isn't aluminium carbide? A label doesn't mean too much unless you know the history of the contents or there is some sort of warranty -
it was sold to you as Al4C3.
It's a bit on the dark side to likely be actual Al4C3 that had slowly reacted with moisture (you've not explained what 'sealed' was - pressure fit
lid, tape, soldered)
Have you tried to determine if it is coated with oil or similar material? Does it show any reaction to aqueous HCl or NaOH? There are a lot of things
that can be described as grey-brown powders, a little more data would be helpful.
garage chemist - 6-2-2008 at 07:58
If I remember correctly Al4C3 doesn't react with water with clearly visible speed, only with HCl. Try that.
After all, the Al(OH)3 product is insoluble in pure water and might be the cause of passivation, just like Al metal doesn't react with pure water.
12AX7 - 6-2-2008 at 08:59
The Al4C3 I made (by arc heating a mixture of aluminum and charcoal) was metallic, brittle and decomposed to powder on extended exposure to
atmosphere.
It does not passivate, but it does not react quickly with air or water either.
Tim
jokull - 6-2-2008 at 09:13
Hi.
I got curious on this topic, but when I'm not sure about a material my first source to consult is a MSDS, so here you are:
Attachment: aluminumcarbideMSDS.pdf (81kB)
This file has been downloaded 728 times
ScienceGeek - 6-2-2008 at 13:00
First of all, really appreciate all your feedback!
I'm very sure that the hermetically sealed container did in fact contain Aluminum Carbide. It had a "professional" label on it.
I've consulted numerous sources trying to find out what has happened, but unfortunately, no results.
It did not react, whatsoever, with HCl. It just sank to the bottom.
With NaOH, a slight fizzing was heard, but no bubbling or evolution of any significant amount of gas.
Any new ideas?
[Edit]: Was able to light a "bubble", but unable to determine of it was H2 or CH4.
[Edited on 7-2-2008 by ScienceGeek]
