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if i electrolyse potassium chloride constantly, will i make perchlorate? Answered

i am about to electrolyse a large amount of potassium chloride to get potassium chlorate, however i dont want to get any potassium perchlorate.
what i plan on doing, is connecting a plastic tube to my chlorine generator, and then have the chlorine pass through my potassium chloride solution, which will stay at about 50-80 degrees celcius , and what i hope will happen is, as soon any potassium hydroxide is formed, it will react with the chlorine to turn into chlorite, which at that tempurature should then turn into 2 parts chloride and 1 part chlorate.
so that way i eventually get a 99% yeild of potassium chlorate.
that way i wont end up losing any chlorine from the solution.

however, this means i will have to electrolyse the solution 3 times longer, so i want to know if this extended electrolysis will cause the formation of any potassium perchlorate

6 Replies

Prfesser (author)2011-02-14

Perchlorate obtained directly via electrolysis will always have some amount of chlorate contamination, and vice versa.

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oldmanbeefjerky (author)Prfesser2011-02-14

is there maybe some kind of scientific rule or equation that i could use to make and approximate estimate as to howlong i should electrolyse the water with a certain amount of watts to minimise perchlorate production?

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westfw (author)oldmanbeefjerky2011-04-03

Yeah; approximately.  You're converting Cl- to Cl+7, so you'll need to get another 8 electrons from somewhere.  So for each mole of perchlorate produced, you'll need at least 8 moles of electrons.  One mole of electrons is about 27 amp hours.  So... "lots."  Run 27 Amps through for 8 hours and you'd be about right.  Any electrons you waste doing other things will be ... wasted.

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oldmanbeefjerky (author)westfw2011-04-05

and would this same rule apply if i were to halfe that , but in half the time?
and will the reaction completely convert if its warm, at say, 80 celcius, as i have heard that the rection just converts chloride into hypochlorite, which must be boiled before it is chlorate, at whoch point only 1 third is converted.
is boiling neccesary, or will electrolysis convert the hypochlorite into chlorate?

also, whats the rule for this if i want chlorate, not perchlorate?

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westfw (author)oldmanbeefjerky2011-04-06

My numbers are very theoretical. In reality, your anode dissolves into mush before you get to the chlorate phase and you get nothing, and even under ideal circumstances you don't get "complete conversion." There's a fair amount of technical info on the web; just stay away from the Kewl Bombz sites.
There is a lot of engineering to getting chlorate or perchlorate production to work; temperature, stirring, electrode materials, etc.

Also solubility. My understanding is that the electrolysis is usually carried out using sodium salts; the potassium products and intermediates aren't soluble enough. Once you get your sodium perchlorate you react it with potassium chloride and purify by recrystallization.

Electrolysis will go all the way to perchlorate under proper circumstances. I believe that this is essentially the commercial manufacturing technique. But it's complicated. One thing I remember is that for chlorate you use cold dilute solutions and for perchlorate you use hot concentrated solutions. Or the other way around. I haven't done it, I don't know how to do it, and even if I did I probably wouldn't tell you. I know a bit of the theory...

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