Sciencemadness Discussion Board

NaOH, S and Al flash.

knowledgeSponge - 8-9-2015 at 03:10

Good day!

I saw some video on Youtube, where guy made something like flash powder from Aluminium, sulphur and sodium hydroxide powders.

It burns really interesting. In description he wrote, that powder absorbs water from paper and ignites. I saw some gasses/smoke before it ignited. and it takes some time from "smoking" to flash.

Can some of you guys explain the reactions happening there, because google doesnt help.

Video of that powder

byko3y - 8-9-2015 at 04:45

I'm sure it's NaNO3.

knowledgeSponge - 8-9-2015 at 05:39

Quote: Originally posted by byko3y  
I'm sure it's NaNO3.


You mean instead of NaOH? Should it work if that was NaNO3 ? Can NaNO3 could pull water out from paper so quickly?

blogfast25 - 8-9-2015 at 06:16

It's NaOH, not NaNO3. With NaNO3 it would burn much hotter. And it would not auto-ignite either.

Firstly NaOH reacts with Al forming sodium aluminate. This is a slow reaction but it does generate quite a bit of heat. Once hot enough you get 2 Al + 3 S === > Al2S3, which is both fast and very exothermic.

knowledgeSponge - 8-9-2015 at 08:09

Quote: Originally posted by blogfast25  
It's NaOH, not NaNO3. With NaNO3 it would burn much hotter. And it would not auto-ignite either.

Firstly NaOH reacts with Al forming sodium aluminate. This is a slow reaction but it does generate quite a bit of heat. Once hot enough you get 2 Al + 3 S === > Al2S3, which is both fast and very exothermic.



He described:
"Reacting mechanism might be related to NaOH, absorbing and reacting with water and that reacting with aluminum, both of wich makes a lot of heat and ignites sulphur, which burning heats up to temperature, to react with aluminum!"

So that might be it?

blogfast25 - 8-9-2015 at 08:31

Quote: Originally posted by knowledgeSponge  

So that might be it?



Something like that, yes.