Can't produce chlorine gas!

[lawrencelaptop]

Need help! God knows why, but when trying to electrolysise sodium chloride solution I can only ever produce hydrogen from the cathode, and brown malleable metal chips and a blue swirling cloud in the solution from the anode. I can only assume that the bubbles at the cathode are hydrogen (cant do s-p test cause I'm not producing enough) and that the flakes or brown are pieces of copper chloride.

I need gaseous chlorine though!

 

Please help!

[DrP]

Pretty sure you wont get Cl like this. The Salt can't be in solution and needs to be molten to do electrolysis with it. However - this isn't possible with your home set up as it would be too dangerous.

 

Are there any other ways of Chlorine that you know of?

[lawrencelaptop]

Pretty sure you wont get Cl like this. The Salt can't be in solution and needs to be molten to do electrolysis with it. However - this isn't possible with your home set up as it would be too dangerous.

 

Are there any other ways of Chlorine that you know of?

 

No i know this is possible- a solution would allow the ions to carry charge, thereby allowing chlorine to be released at the anode when it ditches electrons. The chlorine then bonds with another chlorine particle to become Cl(2), which in other words is gaseous Chlorine.

 

This is because the Chlorine wins out against the hydroxide due to its much greater reactivity.

 

Still dont get how its not producing chlorine gas either? BTW, on the off hand safety is not a concern- the hydrogen I am containing safely and I have a chemical mask, googles and an apron to combat harmful chemicals and the inhalation of toxic chlorine. Molten is not a problem either, seeing as i know for a cert that doing this with brine is possible.

[Fuzzwood]

By the looks of it, you are using a voltage that is way too high. It's like boiling off 100 ml of ethanol with an industrial heater.

[lawrencelaptop]

What effect would the voltage have on the production of chlorine gas? Just wondering, cause I have used about 20 in this assuming it would only affect the speed of the production of chlorine gas. Actually, now I come to think of it I did try a nine volt battery but that didn't work either :S

[Mr Skeptic]

I'm pretty sure that if you mix sodium hydroxide with chlorine the chlorine is going to react with the sodium. So, any Na you get reacts with the water immediately to form NaOH, and if you did manage to form Cl, it would react with that and you're back where you started. Meanwhile, the H2O is much easier to split apart.

[lawrencelaptop]

I'm pretty sure that if you mix sodium hydroxide with chlorine the chlorine is going to react with the sodium. So, any Na you get reacts with the water immediately to form NaOH, and if you did manage to form Cl, it would react with that and you're back where you started. Meanwhile, the H2O is much easier to split apart.

 

Yet I've succeeded in bubbling off chlorine gas before in class? I genuinely don't understand where this is going wrong :S

[TheJames]

The sodium made will react with the water to form sodium hydroxide.

The hydrogen will just bubble up on the cathode

At the anode you'll get oxygen and chlorine.

 

I suggest you try this in

Water and sodium chloride mix with graphite electrodes (just break open a pencil)

[Justonium]

It's the electrode. It's getting oxidized instead of the chloride ions in the solution. To oxidize these, you will need a non reactive electrode. Try graphite. Also, as you're cell runs, chlorine production will soon stop, as the solution becomes more basic. You will then be making hypochlorite ions instead. To prevent this, you need to separate the solutions by the anode and by the cathode. You can complete the circuit easily enough with a salt bridge--a sliced hotdog or a cloth soaked in electrolyte will work OK.

[Cropduster23]

I would suggest mixing hydrogen peroxide with toilet bowl cleaner. That will make lots of chlorine. I think.

[Leader Bee]

Yes, bleach tends to have a lot of chlorine in it.

 

What about alcohol & liquid chlorine?

Edited July 8, 2010 by Leader Bee

[Mr Skeptic]

I would suggest mixing hydrogen peroxide with toilet bowl cleaner. That will make lots of chlorine. I think.

 

I would suggest not breathing chlorine since it can and will kill you.

[missgeek]

use brine, 12v and carbon electrodes. if doing it by electrolysis.

 

if not and you need a lot of chlorine use potassium permanganate and hydrochloric acid as strong as you can get. brick cleaner has a high percentage of hcl.

 

you need to produce it in a safe place with adequet ventilation i.e a fume cupboard as the slightest bit in your nose could hospitalize you

[weiming1998]

Electrolysis of salt is an extremely inefficient (but cheap) way of producing chlorine. It is slow, it requires a salt bridge, and graphite/platinum anodes are needed to prevent corrosion and loss of yield due to the chlorine reacting with the anode.

 

There are so many very easy ways to produce chlorine gas. Combining bleach solution (NaClO/NaCl) or bleaching powder/pool chlorine (Ca(ClO)2/CaCl2) and a (relatively) strong acid (sulfuric, phosphoric, oxalic, etc) will produce chlorine, since the strong acid will make a mix of hypochlorous acid and hydrochloric acid on site, which will react with each other, forming chlorine. Using hydrochloric acid directly is fine too (in fact, the reaction would be faster).

 

Another method of producing chlorine is reacting chlorine tablets (trichloroisocyanuric acid, TCCA for short) with hydrochloric acid, or similarly with a chloride salt and a strong acid. Reacting HCl with a strong oxidizing agent like KMnO4 or MnO2 will produce chlorine as well. Reacting H2O2 and HCl will not produce Cl2 in appreciable quantities, though, due to the inability of H2O2 to directly oxidize HCl to HClO, since hypochlorites react with H2O2 in a comproportionation to form a chloride and oxygen.

 

In my opinion, if you want to make chlorine gas for chemical synthesis, not just as a curiosity, it's definitely worth it to get the chemicals and make it chemically instead of electrolytically.

Edited October 16, 2012 by weiming1998

[vampares]

elementalscientific.net formerly Hagenow carries platinum wire. I have used it in such situations. You should be able to order in lengths longer than one inch. It doesn't provide much surface area. Graphite that isn't destroyed is hard to come by.

 

You may also try adding muriatic acid.

Edited October 19, 2012 by vampares

[Peoplethinkweird]

I have a quick question why does the amount of volts matter, wouldn't the amps matter more because amps are the passage of electrons though a point so the more electrons, the more efficient the electrochemistry would be, wouldn't it? . btw I have no idea how to do electrochemistry, I am just an electricity fanatic.

[Moontanman]

I produced chlorine this way in high school but that was 40 years ago, evacuated the class and destroyed the apparatus...

[khlor]

 

 

Yet I've succeeded in bubbling off chlorine gas before in class? I genuinely don't understand where this is going wrong :S

 

Strange. about one year, I had a homemade setup to make chlorine gas, I used a heavy concentrated NaCl solution and graphite rods (which I got from AA batteries, I think D batteries can do a better work) and worked. of course slowly, but worked. I waited about 6 hours to get something about 25ml of chlorine gas. and I never had problem with the secondary reaction. look out for the size of the electrodes. I think that can be a problem. or may be the current. because according with the faraday's law for the electrolysis, current is what matters.

[Sensei]

Strange. about one year, I had a homemade setup to make chlorine gas, I used a heavy concentrated NaCl solution and graphite rods (which I got from AA batteries, I think D batteries can do a better work) and worked. of course slowly, but worked. I waited about 6 hours to get something about 25ml of chlorine gas. and I never had problem with the secondary reaction.

I have made couple devices for fast production of Hydrogen, Oxygen and Chlorine, and NaOH (because had enough waiting for slow battery rate).

Mine normal rate is 1 Liter of Hydrogen per hour easily. Couple times measured.

 

 

look out for the size of the electrodes. I think that can be a problem. or may be the current. because according with the faraday's law for the electrolysis, current is what matters.

 

The bigger area of electrodes, the more current is flowing.

But usually people are using 60 grams of NaCl and 18 grams of H2O which has volume = ~28 cm^3, so it's hard to use large size electrodes..

 

But I bet, he used metal which is immediately reacting with solution.

If I use steel or aluminum for positive electrode, there is often no sign of Chlorine, instead electrode is dissolving.

You need/should use carbon-graphite electrode for positive electrode (or better for both).

 

1 A * s = 1 C

1 C / e = 1 C / 1.6*10^-19 = 6.25*10^18 electrons

(in theory) one electron can split H2O to OH- and H+

So there are needed 2 electrons to produce one molecule H2

 

1 L of H2 has mass 0.08988 g/L

1 molecule of H2 has mass 2 * 1.0078 g/Na = 2 * 1.67*10^-24 g

so in 1 L there is 0.08988 g/3.3469*10^-24 g = 2.68*10^22 molecules of H2

2.68*10^22 / 3600 seconds = 7.459*10^18 molecules produced per second

*2 electrons needed to each molecule=

1.492*10^19 electrons per second needed

Which is 2.387 A average.

 

I can easily go beyond this current. Today I was using 5 A to produce Hydrogen in experiment.

 

[pyroglycerine]

But I bet, he used metal which is immediately reacting with solution.

 

I agree.

I also did this experiment back in high school, with graphite electrodes.

 

I produced chlorine this way in high school but that was 40 years ago, evacuated the class and destroyed the apparatus...

 

Same think happened to me! I foolishly knocked over a conical flask full of solution which was giving out chlorine gas , and we had to evacuate the class.

For at least a month they called me a Nazi

 

EDIT: SORRY! I Didn't mean to necropost, I just forgot to read the date!

Edited April 9, 2014 by pyroglycerine

[paulsutton]

On 2/25/2010 at 1:29 PM, DrP said:

Pretty sure you wont get Cl like this. The Salt can't be in solution and needs to be molten to do electrolysis with it. However - this isn't possible with your home set up as it would be too dangerous.

 

Are there any other ways of Chlorine that you know of?

I think swimming pool chemicals contain  chlorine,   my chemistry set also had I think Calcium Oxy Chloride, which I think  decomposed in to maybe Calcium Oxide and Chlorine.

Problem is that the gas is still dangerous,  in a lab you would probably use a fume cupboard for handling it.   I can't help much with this though.