Making chlorine

[Runninfarmer]

I don't know if this was on a previous post, but I tried to make chlorine by electrolyzing saturated salt solution. I used an inverted test tube full of water over where chlorine is produced and it naturally displaced the water. The air in the test tube wasn't greenish, but I knew it had to do with chlorine because it had a chlorine smell when I pulled the test tube out of the solution. Was I making chlorine or an oxygen/ hydrogen compund with chlorine? If it wasn't pure chlorine, how can I change my setup to make pure chlorine? Thanks

[MolotovCocktail]

Why do you want to make pure chlorine??? Isn't chlorine poisonous?

[Runninfarmer]

I knew people would be wondering, I just wanted to cork it as a collectibe for an element set.

[YT2095]

HCl and Bleach (NaOCl) or KMNO4 or MnO2 will all make Cl2 gas.

 

but do this in Very small quantities and in a fume cuboard or ourdoors.

and don`t use "Cork" the Cl2 will attack it quite quickly.

[jdurg]

In low concentrations, Cl2 is an INCREDIBLY pale green color that you can almost not see. You should put a white piece of paper behind the tube, or look through the tube from the top end to see if you can notice the green color. When you see samples of chlorine that have an intense green-yellow color to them, it's usually a fairly substantial amount in a container. I fell under the same impression that chlorine always had a deep coloration to it until I made my first batch and saw that it really didn't.

 

BTW, I made my chlorine by taking a calcium hypochlorite "paste" made with dry Ca(OCl)2 and water, then added concentrated HCl to it. The gas was bubbled through water to remove any excess HCl, then passed through some anhydrous NaHCO3 to remove any further moisture. The dry Cl2 was then sealed in a glass ampoule.

[woelen]

Well, if you have a test tube, filled with pure chlorine, you can easily see the chlorine. A 1.5 cm (usual thickness of a test tube) layer of chlorine is not impressively green, but one should definitely see the color.

 

Have a look at this, at the picture of the left test tube: http://woelen.scheikunde.net/science/chem/exps/clo2/index.html

Not impressive, but visible. The gas ClO2 is much more impressive.

 

However, electrolysis of NaCl (with graphite electrodes) does not give very pure chlorine at the anode. Especially if the applied voltage is too high, then a fairly strong side reaction occurs, where water is oxidized and oxygen + acid are produced at the anode, instead of chlorine. So, in practice you get Cl2, but also quite some O2. Things are even worse, if you collect the gas in an inverted test tube. Cl2 is soluble in water quite well (IIRC 3 liter of gas per liter of water), while O2 hardly is soluble (IIRC a few tens of ml per liter of water). So, a mix of Cl2 and O2 is even enriched more in oxygen, because the Cl2 dissolves in the water, and the O2 does not. So, your gas mix in the test tube may contain several tens of percent of oxygen.

 

So, if you really want to make chlorine for an element collection, do as Jdurg did. Produce the gas by chemical means and clean the gas by bubbling it through water, followed by leading it through a drying agent. I would not prefer NaHCO3, because it will lead to contamination with CO2, I would use CaCl2 instead, which is very cheap and easy to obtain at hardware stores as drying agent for buildings.

 

Also, I would not use Ca(ClO)2, but would use TCCA or Na-DCCA instead. Commercial Ca(ClO)2 contains up to several percents of CaCO3, and the chlorine gas may contain more than 20% of CO2. For most chemical experiments, this is not a real problem, but if you have a small sample for displaying, you want the gas as pure as possible, simply because its color already is quite faint, and diluting it with CO2 makes it even more faint.

[jdurg]

Well the Ca(OCl)2 I used passed the vinegar test. I dropped some in some vinegar and some in some lemon juice to see if any CO2 bubbled off. There was absolutely no bubbling from the solution. The 99% purity listed on the ingredients list was most likely correct. Any CO2 that could have formed would have dissolved along with the HCl during the initial water passing.

 

We actually lost quite a bit of Cl2 into the water during the reaction, but there was enough Cl2 in the test tube to see provided you had a white background, or you looked down the long end of the tube.

[Comandante]

A question about health hazards; If I was to inhale chlorine gas of concentration like the one on woelen's photo, what is the worst thing that can happen to me? What is most likely to happen to me? Assume I inhaled about.. 20mL.

[YT2095]

you wouldn`t get past the 1`st few ml before it knocked you on your ass.

at those sort of concs (and even lower) it`s like being electrocuted, you`de throw the vial.

[Comandante]

Damn that sounds intense! I take it it's worse than SO2 gas? I'm asking 'cause a little bit of SO2 knocked me down hard

[YT2095]

SO2`s not great, but not even Close to Cl2

[jdurg]

You'll start coughing and choking and gasping for air almost immediately. You'll also feel an intense burning sensation in your lungs that won't really go away. Your diaphragm muscle will feel a bit sore from all the VERY hard coughing. The thing is, that's not when the problems will start.

 

A few hours later, you'll find yourself short of breath as the cells in the alveolar sacs in your lungs have been exuding liquid thanks to the damage caused by the chlorine gas. This is known as pulmonary edema and it's where you basically drown in the fluid that is leaking from the cells in your lungs. You may feel fine, but as time goes by the fluid builds up until you just can't breathe any more. That is why chlorine, bromine, and a lot of mustard and war gases are NASTY substances that you absolutely MUST avoid breathing.

[chemhero]

Here's an easier way:

 

Take some bleach (perchlorate) and some acid. Mix, and collect gas.

 

Matt

[YT2095]

bleach isn`t Perchlorate it`s a HypochlorIte.

 

xOCl not xClO4

[chemhero]

Really? Perhaps what I used was something else then. Definatly gave off chlorine when i mixed it with lemon juice. It was Ajax, as a solid powder (make up with water, makes floors all nice and clean and disinfected)

 

Apologies!

 

Matt

[woelen]

It definitely contains no perchlorate. Perchlorates don't give chlorine. In aqueous solution, perchlorate is very inert.

[mrbodean]

Can any one confirm or deny that this is correct: If I mix about 10 ounces of common bleach ( sodium hypochlorite ) in 7 gallons of water and then add about 4 ounces of hydrochloric acid 27% to the same 7 gallons of water the chlorine being generated is " attached " for lack of a better term, to the water molicules and the amount of actual chlorine gas escaping to the air is pretty minimal at best. The foul smell that would eminate from the solution is still chlorine gas but at very low PPM?

[PauloChem]

There is actually MnO2 in battery electrolyte. So if I got a little under my fingernails and then if I ate it wouldnt the HCl from my stomach turn into chlorine. Hahahha

[thedarkshade]

[ce]KMnO4[/ce] and [ce]MnO2[/ce] and generally substances with high oxidative characteristics reacting with [ce]HCl[/ce] with give chlorine.

[John Cuthber]

"There is actually MnO2 in battery electrolyte. So if I got a little under my fingernails and then if I ate it wouldnt the HCl from my stomach turn into chlorine. Hahahha"

Strictly it's not in the electrolyte but in the depolariser.

It would react (rather slowly) with the dilute HCl in your stomach and produce some Cl2. This, in turn would react with something else- food, the lining of the stomach, the enzymes used in digeastion- pretty well whatever it hit first.

 

However, the problem with doing this wouldn't be the Cl2, but the manganese.

 

http://en.wikipedia.org/wiki/Manganism

[PauloChem]

Man now I am scared. Ok so I will need to check everything 1000 times before I do an experiment. But at least i didn't have prolonged exposure more "what fits under a trimmed fingernail"

[Bunny56]

Do the electrolysis with an excess of NaCl. If the free chlorine escapes the water it will stay chlorine and form with each other. Suck the gas off into a dry container

 

Alternatively suck off the gas into a container with a clean set of water, and viola there's relatively pure hydrochloric acid...from table salt

[jdurg]

Do the electrolysis with an excess of NaCl. If the free chlorine escapes the water it will stay chlorine and form with each other. Suck the gas off into a dry container

 

Alternatively suck off the gas into a container with a clean set of water, and viola there's relatively pure hydrochloric acid...from table salt

 

Not really. Cl2 in water will form a mixture of hypochlorous acid and hydrochloric acid. Very far from "pure".

[Edenite]

Not really. Cl2 in water will form a mixture of hypochlorous acid and hydrochloric acid. Very far from "pure".

 

Do you have an idea how concentrated it can get? Im thinking if you keep distilling batch after batch, and run it through the same water, its concentrations should increase, no?

[wathq777]

hi

Dont be confused, at anode chlorine is evolved ,it could be mixed with oxygen depending on the electrode used and on the applied potential .........so choose the anodic reaction provided that the hose above the electrode is directed to the inside of iverted flask in such a way to minimize losses due to chlorine solubility in electrolyte