m1tanker78
National Hazard
Posts: 685
Registered: 5-1-2011
Member Is Offline
Mood: No Mood
|
|
Sodium In Naphthalene - Observations
NOTE: This thread is a child of the potassium thread.
I conducted a simple experiment to test naphthalene for being a potential coalescing medium for sodium (assume K). The box of moth balls claims N'ne
in 99.95% purity so I didn't question it much. Shortly after the large prills melted, I placed two ~ 4mm beads of sodium in the liquid. To my
surprise, they sank at times and at others floated (independently of each other). I played with the temperature some, even reaching N'ne's BP at
times. I simply couldn't get the beads to reliably float.
I gave up on floating sodium and moved to coalescing. From Na's MP up though close to N'ne's BP, the sodium beads retained their general shape when
deformed. They pulled together into a semi-sperical shape only when N'ne approached BP. The sodium could be 'shredded' by simply squeezing it or
agitating the bead. I placed a ~ 3mm bead of low potassium NaK alloy in the liquid. This bead [barely] floated throughout the remainder of the
experiment (lower density).
I concluded from this simple experiment that the metal and the medium had similar densities in the described temperature range. Assuming the purity is
as described on the package, naphthalene is not an acceptable medium for coalescing Na but may potentially be suitable for creating a sodium
dispersion within the same (with proper agitation). I believe the liquid N'ne has low surface tension but I'll leave that to those who are
more knowledgeable.
Also note that it's a bad day to be a moth in my garage. 
Tom
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
But no reaction at all with the sodium: that's quite interesting in itself.
For making dispersions of sodium, toluene (or xylene, off the top of my head) is more suitable. High speed stirring and rapid cooling (IIRW) can
create 'sodium sand'. Interesting for certain reactions using finely divided sodium... I believe Wiki has an entry on it.
|
|
|
m1tanker78
National Hazard
Posts: 685
Registered: 5-1-2011
Member Is Offline
Mood: No Mood
|
|
No outwardly apparent reaction. The beads formed a wrinkly dull grey skin but I believe this could have occurred due to the low surface tension. No
joy coalescing even when the beads were manually brought in contact with one another. I took some video initially but quit because the smoke pretty
much screened the view. I'd need to repeat this in glass for proper viewing.
The dispersion idea is just something that I kicked around in my head. I know naphthalene probably isn't an ideal carrier for most organic reactions
but it's cheap and very OTC. It seems to [slowly] dissolve in mineral oil at RT as the recovered Na beads no longer have the waxy coating and the oil
smells a bit like a closet.
Tom
|
|
|
kmno4
International Hazard
Posts: 1497
Registered: 1-6-2005
Location: Silly, stupid country
Member Is Offline
Mood: No Mood
|
|
Naphthalene reacts with Na (and other similar metals) giving salts with strongly colored radical naphthalene anion (or dianion, depends on
conditions). The best solvents for this reaction are ethers, but they are slowly attacked by this very reactive anion (H-abstraction). Mentioned color
is usually green-black.
|
|
|
m1tanker78
National Hazard
Posts: 685
Registered: 5-1-2011
Member Is Offline
Mood: No Mood
|
|
Thanks for the info kmno4. I remelted the naphthalene and dropped one of the original sodium pieces back in. I kept the N'ne just above MP this time
so I could see more of what was happening. I uploaded a short clip to show that there does appear to be some reactivity. Small bubbles can be seen
periodically (if you squint real hard). Once again, poor lighting is needed to prevent the smoke screen effect...
<iframe sandbox width="640" height="510" src="http://www.youtube.com/embed/rHDWDoQmqas?rel=0" frameborder="0" allowfullscreen></iframe>
Tank
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
