Sciencemadness Discussion Board

Weird foamy stuff on my NaClO

Reverend Necroticus Rex - 20-6-2004 at 15:43

I made some sodium hypochlorite a few days ago by bubbling chlorine through hot conc. NaOH solution, and when I went to use it today, there was a thick layer of nasty looking foam on the top of the jar, I suspect that the amount of Cl I had used while making it may have been a touch on the large side, and not the entire top of the contents of the jar it's stored in has turned to a quite dense white foam, sort of like marshmallow and the solution smells nothing like bleach.

Is it possible that the chlorate may have been formed instead of or alongside the hypochlorite by formation of hypochlorous and hydrochloric acid in situ forming NaCl which is then turned to NaClO3 by the ongoing chlorination?

BromicAcid - 20-6-2004 at 15:52

Hot NaOH with chlorine added produces almost entirely chlorate. The solution must be kept cool (10 - 15 C) to produce NaOCl like you were intending to. Perchlorate is not possible in this manner.

Reverend Necroticus Rex - 20-6-2004 at 15:54

I am actually quite glad to have the chlorate, not entirely bad, as I had run out of NaClO3 :D

I bet the foam on the top of the jar was caused by the remaining chlorine bubbling up through the solution, there was quite a fizz of gas released as I unscrewed the lid on the jar, i bet the foam will be good when it dries to make a superfine chlorate powder, great for pyrotechnics :D

[Edited on 20-6-2004 by Reverend Necroticus Rex]

electrolysis of NaOH + NaCl

guy - 20-6-2004 at 16:04

Will electrolysis of a hot solution of NaOh and NaCl yeild a good amount of sodium chlorate?

BromicAcid - 20-6-2004 at 16:36

A chlorate cell such as what you just asked about are heavily covered, both here and expecially elsewhere on the internet. The addition of NaOH is not necessary as the NaCl breaks down to NaOH and Cl2 as the electrolysis proceeds. But there is plenty of information elsewhere.

Reverend Necroticus Rex - 21-6-2004 at 11:04

The chlorate from my (failed?) reaction has crystallised in its jar, with a layer of NaOH-slime on the top, and formed a mas of very pretty and well formed crystals, however they are contaminated with quite a lot of NaOH :mad: I am going to make a hot solution of the whole thing and chlorinate again in an effort to remove the NaOH and hopefully I will be left with some nice pure NaClO3 :D

Esplosivo - 21-6-2004 at 11:17

Would adding sodium carbonate to the solution of the mixture precipitate sodium hydrogen carbonate? The sodium carbonate must be added slowly to prevent excess of carbonate dissolved.

NH3?

guy - 22-6-2004 at 12:57

I made a little Potaasium chlorate by adding KNO3 to NaClO3. There was a smell of ammonia. How could this be?

Esplosivo - 22-6-2004 at 13:04

What was your source of NaClO3? You must have some impurities somewhere, most probably aluminium and sodium hydroxide which give off NH3 on rxn with a nitrate (/nitrite).

guy - 22-6-2004 at 13:18

I made my from electrolysis of NaCl so it probably did have some NaOH

Reverend Necroticus Rex - 22-6-2004 at 13:32

I am just going to try repeated washings and recrystallisations of my chlorate, as the NaOH isn't going to crystallise, so I think just repeated recrystallisations will dissolve the chlorate and get rid of the excess NaOH, either that or I will just re-chlorinate it so the rest gets converted :)