Does anyone know where its possible to procure Magnesium or Potasium Perchlorate from in the UK other than making it via electrolysis (I dont have time to go there) or a chemical supplier (My bullshitting isnt too good).

Im still looking after a long time, any idea's?:(

If i could get hold of Magnesium Perchlorate (a dessicant) i could convert it to the potassium salt.

Yeah, magnesium perchlorate is a dessicant, but the only places that I know of to acquire this particular dessicant from are lab suppliers, and it's over-priced :(.
As far as I know, there is no way to buy good amounts of perchlorates in the UK. You might be able to get small amounts from chem suppliers at huge prices, but if you try to order lots they will get suspicious.
You could try heating sodium chlorate (extracted from weedkiller) to just over its mp until it solidifies, then extracting the perchlorate as potassium perchlorate, which has a very low solubility, then purifying it by recrystalisation, and decomposing the chlorate chemically until it tests negative for chlorate ions. But for this you will need a good, stable heat source that you can keep on for hours at several hundred *C, and you must be able to set the temperature to within 20*C or so, because if it gets too hot all you'll get is chloride.
Another idea is oxidation of sodium chlorate by chemical means, for example with sodium persulphate (a spa/pool cleaner). This should work OK I think, if you can get the persulphate. It shouldn't be too hard to find.

I think you can also get sodium persulphate as a circuit board etchant/developer (can't remember which). So just go look in a local Maplins or order from RS/Rapid

Cheers guys,

Ive heard about those methods of conversion before. I ruled out the heating method because like Mr.Cool said, a stable heat source is hard to find. I always assumed persulfates would be hard to get, but the're obviously not that hard after all. I'll have a look around to see what i can find.

EDIT:

Ok, ive had a look around and you can get it [Sodium Persulfate] from electronics suppliers as an etching compound (thanks zaibatsu). I was hoping to find it under pool suppliers (cheaper) but no luck. The closest was Oxygen Shock (Sodium monopersulfate). Anyone know any brand names it goes by??

The persulfate method gave shitty yields according to Wouter Visser.

If you're going to heat, do it in glass. Metal will catalytically decompose the chlorate directly to chloride.

I've been looking into other ways of chemical oxidation, but so far I'm still in the research phase and with one experiment which has given some odd results wich need careful examination, which I don't have any time for in the coming 4 weeks.

In theory, sodiummonoperoxysulfate should work as well as sodiumperoxydisulfate, but you never know. Anyways worth a try since it's cheap as dirt.

Be sure you don't get any ammoniumpersulfate!

Well, I'm guessing the half equations for persulphate oxidation to be:

Na2S2O8 + 2 (H+) + 2 (e-) --> 2 NaHSO4
NaClO3 + H2O --> NaClO4 + 2 (H+) + 2 (e-)

Thus giving an overall equation of:

NaClO3 + Na2S2O8 + H2O --> NaClO4 + 2 NaHSO4

He uses 5mL of a 30g/L persulphate solution, which therefore contains 0.000630 moles of sodium persulphate.
He uses 1g of potassium chlorate, which is 0.00816 moles.

Therefore the molar ratio of persulphate : chlorate that he used is roughly 1:13, and if my half equations are right, it should be 1:1. I can't imagine it being anything like 1:13!!

Hence the shitty yields! :)

Hmm.... possibly it should read "300g/L"..?

I'm wondering too what the reduction of persulfates actually yields. A have a lab experiment which oxidizes I- to I2 and that goes along with the formation of SO4 2- although this could very well depend on reaction conditions..:confused:

You've got a weird way of writing half reactions, normally one only adds H2O to the left side of the half reaction when balancing charges and in basic solution.

I prefer this way:

S2O8(2-) + 2(e-) --> 2SO4(2-)

ClO3(-) - 2(e-) --> ClO4(-)

(I know this isn't mass balanced)

S2O8(2-) + ClO3(-) --> 2SO4(2-) + ClO4(-)

Now, we see that there is a 3- charge on the left side and a 5- charge on the right side.
Therefore we add 2 OH- on the left side and one H2O on the right side.

S2O8(2-) + ClO3(-) + 2OH- --> 2SO4(2-) + ClO4(-) + H2O

By luck, this reaction is directly mass-balanced, usually you have to correct that too.
Now you can adjust the counterions depending on the ones you used (K+, Na+, etc):

Na2S2O8 + NaClO3 + 2NaOH --> 2Na2SO4 + NaClO4 + H2O

It is favorable to use KClO3 here, since this will produce KClO4 which not only makes separation easier (KClO4 is badly soluble in cold water) but also forces the equilibrium to the right. This will also cause a small amount of K2SO4 to be formed, but this will be only minimal, because of the precipitation of K+ by KClO4.

EDIT: Did he work in basic solution? Because that could also be an explanation if you look at this equation (assuming it's correct).

EDIT2: Also, it is extremely important to keep your persulfate ABSOLUTELY DRY, otherwise it will decompose very quickly with the evolution of ozone.

Yeah the solution was basic.

If i remember correctly Sodium or Potassium Hydroxide was used to make the solution very alkaline. I think H+ formation eventually causes the reaction to grind to a halt without something to neutralise it.

H+ formation? Where would the H+ come from? Certainly not from my equation.

I wasnt refering to your equations, but instead to the method proposed by wouter visser.

H+ would come from the equation I guessed at, which is the same as yours, but without the hydroxide to neutralise the bisulphate.
Yes, he did make the solution up to pH 14, somehow I managed to overlook that.

My half equations probably are weird, there is a standard way to write them which I can never remember. But hey, it worked so I'm happy :).

Very quick ozone evolution, hey? Interesting....

That's exactly why you need to balance charges with OH- and H+, otherwise you can never be sure if it's got to be basic or acidic.

In this case it's clear it's got to be basic, so I don't see your problems with H+.

Quick ozone evolution with persulfate only happens in hot solution. Otherwise it's quite slow.
With quickly I meant that it would become useless if stored wet during a week or so.

Whats the solubility of Potassium Peroxydisulfate by the way? I've found one data sheet that claims only 1.1g/100g H2O at 20 degrees C. Thats not too soluble.

My chemistry encyclopedia says soluble in 50 parts of water. So I assume that 1gr dissolves in 50gr of water?

Don't try to dissolve it using hot water, because then it will simply decompose.

The low solubility of K2S2O8 is one more reason to use KClO3 as KClO4 is even less soluble, shifting the equilibrium to the right. If you were to use NaClO3 very soluble NaClO4 would form and the equilibrium would shift to the left.

If you didn't know it already, a equilibrium reaction in a solution shifts to the side of the less soluble salt.

Bollocks,

Sorry i meant Sodium Persulfate, what a retard. Also, theres something confusing going on here. Wouter Visser states:

Neither persulfates, chlorates or perchlorates are destroyed at a significant rate at the temperature of boiling water, so the reaction rate may be increased by boiling a solution containing the reactants.

But are they? It would explain the crappy yeilds (if the persulfates were decomposing).

I am fairly sure persulfates are unstable in a hot solution, they already start to decompose when kept moist.

How are they used when etching?

Ps Mods. Can this thread be moved to pyrotechnics, its pretty relevent to the whole pyro thing.

Only admin have mod powers in the RSS section. I was going to move it to chem related until I remembered that...