Gunslingers thread about water lead to discussion about mixing water with stuff.
When I was a kid, we had a swimming pool that I maintained. I used granulated clorine that we bought in 5 gallon buckets.
I was always told to be carefull to not spill any water in the clorine, as adding clorine to water is ok, but adding water to clorine would be bad. I was told it would catch fire or explode or something.
Strangely enough, I never tried it. Is there any truth to this ?
Nope. I spilled water in there at times. The reason you don’t want to do it is it clumps up and becomes a real bitch to scoop out and dump in the pool in an even amount.
Theoretically it could happen. Think back to your HS chemistry class: “Always add acids to bases, never bases to acids.”
Well, I’m not really sure in what form you were getting the chlorine…certainly not elemental. So let’s assume that it is in some acidic form or another. The acid-base thing is because of the large energy released by rapid proton transfer. In acid-base reactions, there is a very favorable transfer of a proton from the acid to the base. Now if you have a little acid in a lot of base, it bops around a lot and not muuch happens, though you will notice the exotherm. Other way around, and suddenly every basic molecule in the system is protonated real fast. Lots-o-heat. Of course, it’s not really too dangerous if you’re carefulf; I do it all the time in the lab. You just don’t want to be holding the glassware while you do it.
So with regards to the OP, that may be part of it…
But water has a pH of 7. It is neither a base nor an acid.
Ha! That’s what they’d like you to think 
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Water is often somewhat acidic; it picks up CO2 from the air.
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Other than that, water is more acurately both an acid and a base. It’s just a weak acid and a weak base. Add acid to it, and it picks up protons (and is therefore a base). Add base to it, and it donates protons (hello acid).
If you doubt me (or just for fun), go find some NaOH pellets (outside of a lab I really wouldn’t know where, but I know they can be had). Dissolve them in a minimal amount of water. Enjoy your handwarmer… 
It’s Kudos, with a K.
Just correcting the spelling of my rewards…
They always told me the same thing (always pour _____ into the water, not water into ______) but they never gave a satisfactory explanation.
I think what ricepad was trying to state was “Add acid to water, never add water to acid.”
The reason for this is that acid is only reactive with water in it. If you pour water into straight acid you get highly concentrated acid that can heat up rapidly. Pour straight acid into water and you get a weak concentration of acid that gets gradually stronger. I think the same applies with your chlorine.
Adding a little water to the chlorine shouldn’t be too bad. Most of the time clumping is all you would see, but I suppose if some of the chlorine disolved and pasty fluid in the plastic container got hot enough there could be problems. Best to keep the stuff dry.
What you don’t want to do is add brake fluid or other oily stuff. I watched a Haz Mat instructor do this with a single tablet of pool chlorine and a small bottle of brake fluid in a metal bowl. It took a while to get started, but then the smoke/gas it kicked off when going full blast was wild. It was a good thing the teacher had his suit and gear ready.
I worry about supermarkets, drugstores, and Walmart type places when there are earthquakes, because it would be easy for containers to break and mix all sorts of crap. Bleach and Ammonia mixing makes chlorine gas which could kill anyone trapped pretty fast. Chlorine tabs and motor oil or any petroleum based stuff could flare up and torch a place quick. I’ve seen stuff in neighbors garages that were the equivalent of time bombs. Scary. Needs more thought and education.
> But water has a pH of 7. It is neither a base nor an acid.
Pool water’s a little higher than that.
The reason you add acid to water and not the other way around has to do with the heat of soultion of acids. Concentrated acids have a high heat of solution. That means when they give off a lot of heat when dissolved in water. If you add acid to water the heat builds up slowly in a large heat sink (the water). When you add water to acid the acid tries to solvate in the water and it heats up the water very rapidly. The water boils causing the acid to splash up into the faces of everyone nearby.
This is similar to what Padeye said, but the rule applies to diluting of all concentrate acids, not just straight acids. It think what you mean by straight acids are solid for crystalized acids. These are common forms for many organic acids (citric acid, for example). The most powerful acids (HCl, H2SO4) can’t be crystalized at room temparture. They are usually transported in 12 M solutions. But the “Add Acid” rule still applies.
As far as the OP, I’m not sure what form of chlorine you are dealing with. I’m guessing it is sodium hypochlorite (NaClO4). I’m not sure the heat of solution of that sodium hypochlorite is but I doubt its high enough to cause a fire. There might be some fumes released; esentially spilling water into a bucket of granulated sodium hypochlorite creates a very concentrated bleach solution. I think the fire risk is low, though.
I was always told to remember this by the rhyme:
“Do what you oughta, add the acid to the watta”
While heat of solution is probably a good reason to add [highly reactive whatever] to water rather than vice versa, there’s a simpler, more universal reason: When you pour water into something, it often splashes. The splash material generally consists mainly of the stuff into which you’re pouring Chemical X. For example, pouring water into a concentrated acid solution can splash concentrated acid on you (at least at first); pouring concentrated acid (aside from my klutzy “missing the container” problem) is less likely to burn you–you would get splashed with a much more dilute solution.
Also, wet NaClO4 (as in dampened granulate) will burn your skin if it splatters on you, as will highly concentrated solutions. If you scatter it into the pool dry, you avoid these problems (unless someone is in the pool).
Don’t be hijacking us into a Powerpuff Girls thread.
There may be some truth in what you said Balance, but there is definitely a difference between adding acid to water and adding water to acid. I’ve done it the correct way thousands of times and the incorrect way a couple of times. Each time I added water to acid, I was aware that I had made a mistake right away. There is considerably more splashing and fizzing. Thankfully I was adding the water slowly and I had eye protection (always wear your goggles, people!). And in none of the cases was the acid particularly concentrated. It was freshman chemistry, they didn’t let us mess around with the real stuff.
I always remember it by AA (add acid). I usually don’t buy into those mnemonic chemistry devices, MinkMan, but this is one I remember and use. Never heard of your rhyme, but it doesn’t surprise me. Chemistry is full of mnemonics, it is probably only out paced in that regard by medicine.
If there is any doubt as to the “poof” potential of adding water to pool chemicals, ask the Springfield, MA Fire Department. In 1986, they had an enormous fire in a warehouse storing calcium hypochlorate. A combination of a leaky roof and a sprinkler system created a huge fire…the roof leaked in a rain storm, starting a small fire. The sprinklers then activated, making the fire much, much worse. The Fire Dept’s solution was to flood the building for the next 3 days and evacuate 30,000 people. It worked, but it also taught those of us familiar with the incident to put the pool chemicals in the water, not the water in the pool chemicals.
On a personal note, I’ve also seen one of those floating chlorine-dispensing ducks spinning around and hissing, followed by it exploding, all because it was overloaded with cholrine tablets. Lends itself to a whole different level of respect for common household chemicals.
On a related note, definitely do not mix water chlorine and sugar. In HS, a friend and I made several of these bombs by combining the ingredients in a two liter soda bottle. Interestingly, a two-liter bottle fits perfectly into a mailbox …
Sua
Wow, this is a cool board!
Thanks everyone for your responses, you gave a lot of good info. Engineer Don, you made a really good point about paying attention to storage with other chemicals in the garage. Especially with kids running around, things could get knocked over
Oh, and please don’t mention Chemical X around me again. If it wasn’t for those girls I would RULE the City of Townville.