reacting halogens with alkali metals

[hermanntrude]

I've seen many demonstrations of the reaction of sodium with chlorine, and now that i've discovered I have 3 lbs of sodium in my lab and a lecture bottle of chlorine, I will be adding it to my repertoire of demonstrations.

 

However, it occurred to me that we ALSO have bromine and potassium, and iodine, too, for that matter.

 

How dodgy would that be? has anyone ever seen these reactions? has anyone ever tried them themselves? Does anyone have any advice other than "be REALLY careful"?

[jdurg]

I've done the Iodine and Sodium reaction, and have to say that it is VERY boring and poor. I took pure sodium metal just taken out of the oil and rubbed dry. I pressed some pure iodine crystals into the metal until they were completely surrounded and then heated the mixture up. Nothing happened. The I2 just evaporated and the sodium oxidized. When I added a tiny speck of water to the reaction, however, it went off in earnest but nothing too shocking. Kind of disappointing.

 

Potassium in Bromine would be interesting, but also INTENSELY dangerous. Br2, with a drop of water in it, is one of the most reactive substances on Earth. Throwing in some reactive potassium would be more dangerous than demonstrational.

[hermanntrude]

I've done the Iodine and Sodium reaction, and have to say that it is VERY boring and poor. I took pure sodium metal just taken out of the oil and rubbed dry. I pressed some pure iodine crystals into the metal until they were completely surrounded and then heated the mixture up. Nothing happened. The I2 just evaporated and the sodium oxidized. When I added a tiny speck of water to the reaction, however, it went off in earnest but nothing too shocking. Kind of disappointing.

 

Potassium in Bromine would be interesting, but also INTENSELY dangerous. Br2, with a drop of water in it, is one of the most reactive substances on Earth. Throwing in some reactive potassium would be more dangerous than demonstrational.

 

thanks for the info. I suppose that iodine being in the solid phase slows it down a bit. Plus I imagine sodium iodide is less stable than sodium chloride because of the difference in ionic radii

 

I had already decided it probably wasn't worth trying potassium and bromine.

[YT2095]

I`v done Mg with Br2 (it was a little disappointing), and Ca with Br2, it`s quite a bit better.

Both are much safer than K metal.

I have Na and Br2 here, I`v never tried it though, IF I get a quiet half hour I may just have a go (taking pictures of course), although I think I`ll be doing it in the Gas phase, it may be a little safer than Br2(l).

[hermanntrude]

let me know how it goes.

 

How about lithium and bromine or chlorine? probably a bit boring?

[YT2095]

it`ll be in mg quantities when I do it, it`s safer for one and uses less chems, and you`r more likely to see a reaction rather than explosion.

 

I think I may pass on the Li metal though, I rem the last time I used it, I had Li Foil that I wanted to cast as an ingot, so I heated it in a boiling tube (borosilicate) with a He2 atmosphere, and it melted clean through the test tube, caught fire, and then exploded when I threw it in the sink

happily it was only a couple of grams, but it Really doesn`t like Glass!

[hermanntrude]

I wouldnt heat lithium. I'd use the same method as for sodium and chlorine:

 

place a little sand at the bottom of a conical, with a stopper with a tube through it. Fill the flask with chlorine gas. Carefully add a small dollop of sodium to the sand, then drop a single drop of water down the tube, and stand well back.