Generating Cl2 to make hypochlorite

Quote: Originally posted by MrHomeScientist

Potassium permanganate works much better instead, but again I prefer calcium hypochlorite - cheap and easily available. Plus the calcium chloride byproduct can be handy.

Quote: Originally posted by Pulverulescent

Electrolysis is by far the most convenient route to hypochlorites . . . Reading up on the subject to avoid failure in future would be my suggestion!

Quote: Originally posted by mycotheologist

Does the permanganate method require heating?

Quote: Originally posted by MrHomeScientist

I've had good success using calcium hypochlorite and hydrochloric acid, both found at the pool supply store: Ca(ClO)<sub>2</sub> + 4 HCl → CaCl<sub>2</sub> + 2 H<sub>2</sub>O + 2 Cl<sub>2</sub> In my experience, the manganese dioxide method is very slow and requires heating. Potassium permanganate works much better instead, but again I prefer calcium hypochlorite - cheap and easily available. Plus the calcium chloride byproduct can be handy. I'm sure there are lots of methods around the forum, if you use the search tool.

Quote: Originally posted by annaandherdad

I haven't tried to make chlorine but I anticipate a problem that suggests that the MnO2 method might be best. It is that in the other methods (potassium permanganate, bleach, etc) you get the chlorine as soon as you add the HCl. Now I don't have a pressure equalized funnel, so I have to use a thistle tube or some such thing for adding liquid (HCl in this case) to a reaction vessel (a flask). And some amount of gas will come back up the thistle tube, which, considering that it's chlorine, is not so good. But in the MnO2 method, I measure the amount of MnO2 and HCl I need, add them together cold, then stopper the flask and warm it for the Cl2 to come over. It doesn't come out all at once, and none escapes. I enjoy your videos, by the way. They're good science.

Thanks! That's a good point you make; I've ran into the same issue pretty often. I only recently got a pressure equalized addition funnel, so before that I would have to add the reactants and quickly stopper the flask again. This inevitably would result in a burst of gas escaping, which is never fun. I haven't had much luck with MnO2 myself, but that was back when I was first starting out in chemistry so maybe you'll do better. Good luck, and always be careful working with chlorine! All the halogens always give me day-long headaches whenever I work with them Really need to build that fume hood one of these days.

Quote: Originally posted by Pulverulescent

Quote: Electrolysis is by far the most convenient route to hypochlorites . . . Reading up on the subject to avoid failure in future would be my suggestion! I strongly disagree. Making hypochlorites without chlorate contaminsation is nearly impossible with a simple home-made electrolysis cell and besides that, this process is slow and if the wrong type of anode is used, it also produces a lot of crap (e.g. finely powdered graphite) in your solution. In my opinion, electrolysis is next to useless for making hypochlorite. I would indeed make chlorine by chemical means. Use MnO2 if you want a steady stream of chlorine, which can be controlled by means of heat. Use TCCA or Ca(ClO)2 if you have a dripping funnel, with which you easily can regulate the amount of HCl, dripping on the solid material. If you use Ca(ClO)2 then you always will have some CO2 as well. Swimming pool Ca(ClO)2 always contains some CaCO3 as well. TCCA and MnO2 do not suffer from this problem.