How does chlorine evaporation work??!?!?

So my general understanding of chlorine is that it evaporates given enough aeration. Is this hypothesis correct?

When I first started messing with fish stuff I started with freshwater. My tap contained traceable amounts of chlorine (traceable by smell and freshwater chlorine test kit, how ever accurate that is). The test kits I used were dip sticks. I read online that letting your water sit for 24hours with aeration is equivalent to de-chlorinator. After letting it sit for 24 hours, there was no traceable chlorine on my test kit.

So my question is how does the process work? We bleach our rocks, de-chlorinate our water etc. But what exactly is happening behind the seems. Is the chlorine actually evaporating or just breaking down and becoming inert? Does the chlorine actually stay in the water column or does it disappear?

I have bleached rocks using the bleach for a couple days, rinse in RO, soak in RO for a couple days, then dry completely for a day or two in the sun, then soak in saltwater for a couple days, then into the tank. Is the chlorine actually gone from the rocks? or has it just broken down to a harmless untraceable inert form?

 

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my rock nuking instructions includes a step of soaking in a water/baking soda mix to neutralize the bleach... if letting the rocks air dry can satisfactorily evaporate the bleach away... the step seems unnecessary.

curious to see what others have to say too

 

I have bleached about 30lbs of LR rubble (sat in someones basement for a couple years and was beyond sickening), and about 50lbs of rock without the use of the baking soda step. As soon as they were soaked in saltwater for a couple days (last step of the process), I just popped em in my tank. Didn't see any ill affects but I did not test for the chlorine at this time because I only have the FW chlorine test kits.

I'm looking for some answers about what is actually going on chemically, behind the scenes.......in layman's terms please!

 

I believe you are correct,it's actually still there but becomes inert,the only thing imo that evaps is nothing but pure moisture,the chlorine just become neutral

 

I believe it straight up evaporates. There are chemical "binders" of some sort, like Seachem Prime etc that bind to or react with the chlorine to make it inert, but if circulated and exposed to open air it will evaporate, that's part of what you're smelling is the evaporation.
I don't have a chemistry degree or a good source to cite (just some google searches) but I'm pretty sure that's the case.

As far as why the nuking instructions tell you to use baking soda, I have no idea, AFAIK chlorine doesn't affect pH so neutralizing it with baking soda doesn't make sense to me. I wonder if the baking soda was maybe for neutralizing a vinegar bath when "nuking" rocks?

 

drying completly is most important , the bleach left in rocks will crystallize and will come out on next ro rinse also baking soda soak is ur safe guard it will neutralize any traces of bleach left over

 

Well. This the kind of stuff we're doing in Orgo. God I hate it...but I guess it serves some sort of purpose.

I can tell you how to dechlorinate hyrdocarbons...not so much about the live rock. I think it has something to do with the polarity of water and the formations of chlorine radicals binding to the oxygen.

 

correct... and to add to this:
everything is driven by thermodynamics and kinetics. Chlorine is more kinetically stable when it is bonded with a molecule that it can share or give its electrons to. Bottom line is that when put in water the chlorine will do one of two things, go gaseous (the thermodynamic path) and produce cl2(gas)... or bind to a large molecule that pulls in all of chlorines electrons (the kinetic product) such as CCl3(inert molecule).

 

Too many ideas of what happens whirling around. If chlorine evaporated, we would have chlorine rain, no? I do not believe the chlorine odor is the result of chlorine evaporating. That would mean any smell is evaporation when that is not the case.

So far the consensus is that air+chlorine=inert. Take a pool for example....chlorine chemistry forum. The chlorine bonds to almost any element. When inorganics and oxygen is involved, it becomes neutral and turns into a solid inert mass and precipitates to the bottom of the tank or pool. Thats why you constantly have to add chlorine to a pool because it is basically bonding and cleaning at the same time so it gives people the impression that it evaporates with the water, but that is not the case. Chlorine is a gas and has a low boiling point so the only way to make it evaporate is to boil it. It would evap even before the water starts boiling and evaporating. Another way to totally remove chlorine from water is to run the water through carbon and the carbon will soak it up.

So my conclusion and hopefully consensus from all of the above posts and some simple google researching. If you bleach your rock, the chlorine in the bleach dissolves inorganics and kills almost any kind of bacteria. Hence when you drop a rock in that is full of GHA and nasty mucky brown, it comes out snow white and has not one spec of dirt or algae on it. Now the process of drying it out in the sun.....one of the crucial aspects of nuking rock, this makes the chlorine bond to O2 and crystalize and become neutral/inert. The chlorine is still there and is still harmful, just no longer in the water column, but instead, it is a solid, crystallized, form that remains on the rock. Still harmful if ingested. So the second extra crucial step. Rinse the crap out of your rock in RO water after drying completely to make sure all of the crystallized chlorine has been removed. It would not be a bad idea to run a carbon reactor or canister filter with carbon on the last step of the process while the the rock is soaking in Saltwater before it goes in the tank.

As for baking soda. This was added for nuking rock with vinegar which is not as common as bleaching rocks. With bleach, the baking soda is not needed.

When cleaning powerheads and equipment with vinegar, adding the baking soda step to neutralize the vinegar wouldn't be a bad idea.

 

Does sunlight break down chlorine? on my parent's pool, it said to use a sun shade, as this would reduce the amount of chlorine you needed to add. And it did seem to use less when covered or with the shade.