Download Posted December 10, 2019 Posted December 10, 2019 Long story short my graphite electrode chlorate cell failed much more quickly than I anticipated and then some stuff happened and I didn't get around to replacing it leaving me a bit short of the chlorates needed to make some stuff for new years and Christmas. I didn't really have the time to make some more. A solution came to me though: I was taking a look at the chemicals we use for the spa when I realised it was lithium hypochlorite. Next time I was at the hardware store I looked about the pool section and found that they also sold calcium hypochlorite for only $60/10kg. Though I've never done it, I am aware you can make sodium chlorate by heating sodium hypochlorite bleach. It's a bit expensive though (1L of 5% bleach is a few dollars at least), but if I use calcium hypochlorite instead I have the chance to make chlorates very cheaply and quickly. Does anyone have any experience with this? If so, did you do it in a solution or by heating the dry salt? What temperature are we looking for? I have a high temperature probe so I can get accurate measurements. I guess making sodium hypochlorite from calcium hypochlorite is another option but I'd like to ship the additional step.
FrankRizzo Posted December 10, 2019 Posted December 10, 2019 http://www.sciencemadness.org/talk/viewthread.php?tid=10727
AustralianPyromaniac Posted December 11, 2019 Posted December 11, 2019 The reaction you're talking about is possible, however, it is very inefficient both in a chemical sense and in a practical sense as well as being dangerous, complex and highly ill advised. Chemically, only a 1/3rd molar ratio of ClO3- ions can be produced from ClO- which greatly limits the potential yield. Practically, the production of a strongly oxidising agent from a weakly oxidising agent is never favoured. As such, conditions to drive the reaction must be such as to facilitate a conversion which does not want to occur. This means very strong heating in solution so the ions can interact; too much will cause reduction to CaCl2, too little will yield chlorite and hypochlorite. This means lots of danger, lots of unwanted side products and production of Cl2 among other risks and factors which make a synthesis like this downright silly. As I understand it this is what is supposed to occur, 3Ca(ClO)2 --> Ca(ClO3)2 + 2CaCl2. My guess is that even this first step would maybe only account for 30% of the product. Once you've done a double displacement with KCl, tried to get the KClO3 out, and recrystalised it, pushing 10% yield would be a surprise. In any case the reaction is extremely dirty, very dangerous and insanely inefficient not to mention your product will be contaminated with massive amounts of hypochlorite, chlorite and calcium compounds making any composition you produce look terrible and be downright dangerous if you don't have the skill to remove them. Just get a MMO anode and make some chlorate or buy it, or just skip your use of chlorate all together if you may not be ready to use it. Although hard to find, chlorate is available online in even in countries like Australia. Regards, AP
LardmanAttack Posted December 20, 2019 Posted December 20, 2019 I'd have to agree with the post above, I've tried this kind of thing several times before I had a running chlorate cell and its just an absolute waste of time, just put in an order for some MMO or Platinized titanium anodes and if you really need chlorate in the mean time and are willing to waste a bunch of time, i'd say go with the ol' boiling bleach method.
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