Sciencemadness Discussion Board - Liquid sodium hydroxide and aluminum?

Liquid sodium hydroxide and aluminum?

Cou - 28-5-2013 at 18:36

Does aluminum react with molten sodium hydroxide, and what is the equation? Do metals react with sodium hydroxide to make metal hydroxides? Like zinc and NaOH makes zinc hydroxide... I read that it's possible to make sodium this way, because reacting aluminum with aqueous sodium hydroxide, the sodium just reacts with the water and goes away. If it works, I'm going to melt some sodium hydroxide with a meker burner, but I'm afraid it will ruin the glass. Would it work with a copper container?

[Edited on 29-5-2013 by Cou]

elementcollector1 - 28-5-2013 at 20:47

Yes, look it up (it makes sodium aluminate), depends on whether they're amphoteric or not, it's more of a thermite-style reaction than a molten thing (don't play with molten hydroxide! It will murderify you and make you dead!), and maybe (I've seen sodium cuprate, so no promises).

blogfast25 - 29-5-2013 at 04:24

Quote: Originally posted by Cou

If it works, I'm going to melt some sodium hydroxide with a meker burner, but I'm afraid it will ruin the glass. Would it work with a copper container?

[Edited on 29-5-2013 by Cou]

By NO MEANS add aluminium to an NaOH melt, as a violent reaction will result.

As for making sodium from NaOH + 2/3 Al === > Na + 1/3 Al2O3 + 1/2 H2, it isn't worth doing. Read the other thread currently active on 'chemical' sodium.

If you're going to mess with molten NaOH, electrolysing it would be safer and easier.

Fantasma4500 - 29-5-2013 at 06:29

if you want to try this at really small scale take aluminium and melt NaOH in.. sounds interesting.. sadly my carpet very very easily melts.. S:

Bot0nist - 29-5-2013 at 06:33

Oh, and dont melt NaOH in glass! It will digest it. use a suitable metal contianer or crucible...

ScienceSquirrel - 29-5-2013 at 06:48

Aluminium reacts quite readily with solutions of alkali.
Adding it to molten sodium hydroxide will result in a violent reaction that could be extremely dangerous.

kristofvagyok - 29-5-2013 at 12:45

Sodium and potassium hydroxide could be melt in a silver pot. Do not even try aluminium, it will end up as a really nasty accident.

Cou - 29-5-2013 at 12:59

Well i'm sticking to just electrolysis of molten NaOH and KOH now

Metacelsus - 29-5-2013 at 14:45

Electrolysis of molten KOH doesn't work; the K dissolves in the molten KOH.

Finnnicus - 29-5-2013 at 18:18

Nickel! Nickel is the way to go vs strong bases. Even an electroplated layer works great.

blogfast25 - 30-5-2013 at 04:42

Quote: Originally posted by Cheddite Cheese

Electrolysis of molten KOH doesn't work; the K dissolves in the molten KOH.

Hmmm... up to the 50s electrolytic K (from KOH) was the prevailing production method.

Eddygp - 30-5-2013 at 12:14

Don't mix aluminium with molten NaOH!!! Your neighbours have the right to live!!
It forms sodium aluminate. However, I suggest you do that as wet chemistry. A conc. solution of NaOH with Al will follow the next reaction:

NaOH + Al + H2O = NaAlO2 + 3/2 H2

Bot0nist - 30-5-2013 at 12:30

Quote: Originally posted by Eddygp

Don't mix aluminium with molten NaOH!!! Your neighbours have the right to live!!
It forms sodium aluminate. However, I suggest you do that as wet chemistry. A conc. solution of NaOH with Al will follow the next reaction:

NaOH + Al + H2O = NaAlO2 + 3/2 H2

I've done said reaction. It works fine, however, keep in mind that the formed NaAlO<sub>2</sub> will be a gel (per usual) and the hydrogen gas being produced will be full of caustic aerosol, so don't stream it straight into a balloon or breath it. The caustic aerosol is very irritating, and can easily fill a small room, even when just dissolving some foil pieces in 100ml of conc. NaOH solution.

Be careful if you do decide to experiment with molten sodium or potassium hydroxide. It is very nasty stuff and will hurt you badly. There are some cool videos on YouTube showing it dissolving a beaker almost instantly. Scary, scary stuff if you haven't the experience, respect and equipment to handle it safely.

Fantasma4500 - 30-5-2013 at 15:15

just to add....
316 steel IIRC can withstand molten hydroxides.. remember this from one of nurdrages early videos

Bot0nist - 30-5-2013 at 15:50

Thats the video I recal as well. Doesn't hold up like nickel or silver, of course, but if its a pan you dont care to much about, give it a shot. I imagine it will corrode or pit it some. I have never tried it myself though...

DrSchnufflez - 30-5-2013 at 15:54

I use stainless steel measuring cups that I bought for $4 from a kitchen shop. They have been in contact for 3-4 hours with molten hydroxide and show no pitting, just darkening.

hyfalcon - 30-5-2013 at 16:29

It's the nickel in the stainless that makes it resistant.

Fantasma4500 - 31-5-2013 at 03:40

i believe the etching of steel (316?) will be as little as only few millimetres PER YEAR of exposure to molten NaOH

anyhow i got some news for the OP...

i tested this out.. i took first aluminium foil.. didnt do something interesting.. left a hole and suddenly there was no liquid but seemingly nothing left at all..

i then put NaOH pellets on a CPU aluminium cooler and heated..

suddenly a reaction occured!
it was like a tiny little flash, definately very energetic for the simplicity of the reaction..
it was like a yellow flash, like a little poof as you know it from granulated BP (if you do..)

in larger scale this COULD potentially be dangerous
when the small flash has occured a solid remains, plain white and instantly solidifies and flattens out at once

doubt this is sodium metal tho.. but very interesting what so ever

safety lies within amounts used

blogfast25 - 31-5-2013 at 05:02

Quote: Originally posted by hyfalcon

It's the nickel in the stainless that makes it resistant.

Nope. About 11 % of chromium. Assuming by 'stainless' you are referring to Stainless Steel aka Inox.

kmno4 - 31-5-2013 at 07:08

Interesting papers:

Code:

http://www.electrochem.org/dl/ma/201/pdfs/1433.pdf

and

Code:

http://link.springer.com/article/10.1007%2FBF00774695

See also Mellor vol.5, p.217

Seems that vigorous reaction is caused by H2O from commercial NaOH. So before experiment NaOH should be melted and dehydrated.

Hm....

[Edited on 31-5-2013 by kmno4]

Fantasma4500 - 31-5-2013 at 14:00

Quote: Originally posted by kmno4

Interesting papers:

Code:

http://www.electrochem.org/dl/ma/201/pdfs/1433.pdf

and

Code:

http://link.springer.com/article/10.1007%2FBF00774695

See also Mellor vol.5, p.217

Seems that vigorous reaction is caused by H2O from commercial NaOH. So before experiment NaOH should be melted and dehydrated.

Hm....

[Edited on 31-5-2013 by kmno4]

i did try to use the pellets for dragging water out of certain things as in dessication, but didnt seem very strong of a dessicant..
i did however see on the aluminium that after some time the 3 pellets which were melted started to get wet?
i think youre right that theres water in the NaOH.. problem is just that i would need some good steel to 100% dehydrate it..

interesting links.. seem illogical to me that titanium would get etched many many times faster than magnesium and aluminium (and magnesium getting etched slower..?)

hyfalcon - 31-5-2013 at 15:18

Quote: Originally posted by blogfast25

Quote: Originally posted by hyfalcon

It's the nickel in the stainless that makes it resistant.

Nope. About 11 % of chromium. Assuming by 'stainless' you are referring to Stainless Steel aka Inox.

There's that also. It's the nickel that's resistant to the NaOH though.

I've studied the Franklin battery to much not to know that.

Surrealist - 10-6-2018 at 16:27

I tried this and had a much less exciting result than anticipated. 210 g NaOH was heated to the melting point in a stainless steel pot along with aluminum foil pieces totaling 0.5 g. After fifteen minutes, it was molten and the aluminum still shiny. 0.9 g magnesium (one whole piece) to this, and it bubbled with a white halo. This is a good start to confirming that the aluminum may simply passivate too quickly for this to be any good. After two hours, the aluminum was still shiny! Another 27 g aluminum foil was added loosely on top and waited for another hour. No violent reaction occured. 28.5 g of aluminum coated with oxides and sodium hydroxide was easily removed, while the hydroxide “layer” seemed to encase the aluminum and make it very brittle and white. After washing with water very slowly and carefully and adding the solution to the appropriate waste container, the magnesium chunk was even able to be removed, although it was black in some places and now only weighed 0.75g. The stainless steel lid was on the pot at all times except when pictures were taken. It was quite shocking that the $15 hotplate from walmart managed to melt sodium hydroxide (mp 318 C) in the first place. Mineral oil boils at 310 C, just shy of being able to hold molten sodium hydroxide but high enough to handle the potassium sodium hydroxide eutectic. (mp 170 C, .515:.485 Na:K molar ratio) and (218 C, .373:.627 Na:K molar ratio) http://www.crct.polymtl.ca/fact/phase_diagram.php?file=KOH-NaOH.jpg&dir=FTsalt Mineral oil could shield this from the air. Some amalgamation might help the process along. Mercury boils at 357 C. Ill post what happens with this eutectic, amalgamated, protected experiment when I try it, but Ill need to get the mercury from its sulfide first.

AJKOER - 15-6-2018 at 11:23

Sodium aluminate formula is given variously as NaAlO2, NaAl(OH)4 (upon hydration); Na2O·Al2O3, or Na2Al2O4 (see https://en.wikipedia.org/wiki/Sodium_aluminate#Reaction_of_a...).

To prepare NaAl(OH)4, the requested reaction with NaOH is:

Al + NaOH + 3 H2O --> NaAl(OH)4 + 3/2 H2 (g)

or, upon scaling:

2 Al + 2 NaOH + 6 H2O --> 2 NaAl(OH)4 + 3 H2 (g)

However, one does not actually need NaOH here as heating aqueous NaHCO3 with added aluminum foil also creates sodium aluminate and hydrogen gas, as I have done. The reason is hot aqueous NaHCO3 acts like NaOH and will attack aluminum items placed, for example, in a disk washer using sodium bicarbonate per the reaction:

NaHCO3 + H2O + Heat --> H2O + CO2 (g) + NaOH

Or, more generally, the equilibrium (which may be moved to the right as claimed above) is given by:

HCO3− + H2O = H2CO3 + OH− (see https://en.wikipedia.org/wiki/Sodium_bicarbonate )

As NaHCO3 is amphoteric, a possible reaction with the aluminate releasing Al(OH)3:

NaHCO3 + NaAl(OH)4 = Na2CO3 + Al(OH)3 (s) + H2O

Interestingly, aluminum hydroxide is also amphoteric (see http://www.oneonta.edu/faculty/kotzjc/LAB/Complexation.pdf ):

[Al(H2O)3(OH)3] (s) + 3 H3O+ --> [Al(H2O)6]3+ (aq) + 3 H2O

[Al(H2O)3(OH)3] (s) + OH- --> [Al(H2O)2(OH)4]- (aq) + H2O

[Edited on 16-6-2018 by AJKOER]