Question, Can it really be Crystalized Hypochlorous Acid? edit

Hi James,

Since you seem to know something about Hypochlorous acid I am hopeful you can solve a mystery for me!

I have been producing Hydrogen and Chlorine on a small scale for research needs. I built a nice little electrolysis devices to break down NaCl producing H2, Cl2, and NaOH. To protect my cells (from back flash) in the electrolysis device I am bubbling both the H2 and Cl2 through water. I understand that when I do that I create Hypochlorous acid (HClO) on the Cl2 side. My initial thought was this would quickly saturate and the Cl2 would then just pass without any more losses. In general this is what I have seen; except…

Because I don’t want to breath any escaping Cl2 I am operating this in the larger unheated area of my shop, and the electrolysis works fine until the temperature drops below about 5C, then I start to form a light yellowish crystalline precipitant in the bottom of my Cl2 water. Also, where the Cl2 bubbles into the water crystals form ultimately blocking the flow of the Cl2 gas and backing up the electrolysis.

I drained the top of the chlorine water off leaving only a little water and the crystals. I then lightly capped off the bottle and let it warm up. A comparatively large amount of Cl2 was generated popping off the cork many times with a very strong Cl2 odor and Cl2 yellowish gas. The crystals slowly, completely, and cleanly dissolved away. My assumption is, is that I had crystallized HClO in the bottom of my chlorine bottle. What else could it be?

I could not find any data on saturated chlorine water at cool temps, or at what temperature HClO will crystallize. I have no idea for sure this is what is happening. As a stop gap, instead of bubbling my Cl2 through water I am bubbling it through a 20% HCl solution in hopes that the amount of HClO dissolved will be minimized and crystals will not form; but this assumes that it is crystalline HClO. If it is, isn’t this very interesting? Doesn’t it have practical applications for chlorine storage as this is happening at atmospheric pressure and easily obtainable cool temps? Hard to believe… any help would be appreciated.


I thought about this, and looked into it. I suspect your dealing with Hydrate of chlorine, or hydrate of ClO, maybe both, but I'm not a chemist. I put a google book link below that has info on this. From reading it, your dilute HCl will likely make things worse.

http://books.google.com/books?id=qD04AAAAMAAJ&pg=PA243&lpg=PA243&dq=hypochlorous+acid+hydrate&source=web&ots=hRKjwmqIRm&sig=Eb3bLbsf8vDpw4UjqR0_8tQEfvE&hl=en#PPA244,M1

James.folsom (talk) 14:47, 2 April 2008 (UTC)