How to make KClO4

[TATER]

I was wondering if you could make KClO4 by electrolization just like KClO3. if anybody knows how please write back thanks

[woelen]

It can be made (with difficulty) by electrolysing a solution of a chlorate (free of chloride), with suitable really inert anode. But this process is not easy. Making KClO4 at home is not easy and requires quite some experience.

[TATER]

what would work as an inert anode?

[woelen]

Best results are obtained with a titanium anode, covered with a non-permeable coating of ruthenium dioxide.

Second best are platinum anodes, but these are corrodes quite badly already.

 

Both types of anodes are not something the average person has lying around. They are VERY expensive, but if you wish, every now and then, suitable materials are offered on eBay and for $100 or so you could make your own anode.

[TATER]

are their any toxic or dangerous bi- products i should know about?

[YT2095]

do you even know HOW to make a perchlorate?

[TATER]

Don't you have to electrolyze NaNO3 and KNO4 ?

[YT2095]

I`ll take that as a No then.

[John Cuthber]

Tater, a quick hint for you, where exactly did you imagine the chlorine atom in the middle of a perchlorate would come from if you electrolysed NaNO3 and KNO4 (whatever the hell that is)?

 

BTW while I'm quite happy to spell, for example, oxidise with a z ie oxidize, I get upset about "electrolyze" and "hydrolyze". It's not "just a matter of opinion". It's plain wrong. The words are derived from lysis meaning to split.

To make an oxide is to oxidi(s/z)e.

"Electrolyze" only makes sense if you think you are making an "electrol".

[TATER]

I guess i either misread the website or it was totally wrong to begin with. KClO4 needs an oxidizer and a chlorine donor right?

[bob000555]

I guess i either misread the website or it was totally wrong to begin with. KClO4 needs an oxidizer and a chlorine donor right?

 

I think you may have read a web site on the pyrotechnic uses for KClO4 (thou I’ve never herd of it being used as a chlorine donor). Any way electrolysis (with no z ) is very simple(at least for these purposes) : it oxidizes the anion. So if you want KClO3 use Kcl.

[woelen]

It is not simple at all.

 

From a theoretical point of view, it is not just a matter of oxidizing the chloride anion to chlorate. Things are much more complicated through a multi-step reaction over chlorine, hydroxide, hypochlorite and finally chlorate.

 

From a practical point of view, things also are not that easy. You need good electrode material, preferrably some way of current control (which can be as simple as a resistor network) and some means to prevent back-reduction at the cathode.

 

All these subjects, I have covered in more detail on SFN, use the search engine and you'll find.

[bob000555]

But he just asked how to make chlorate he didn’t ask for the chemical basis but here it is:

When an ionic compound dissolves in water it dissociates into it’s component ions in this case K+ and Cl-. As opposites attract the K+ is pulled to the cathode and the Cl- to the anode where its oxidized to Ocl (hypochlorite) the net reaction being Kcl+H2O+e-=>KOCl+H2. Next the same thing happens oxidizing the hypochlorite to chlorate 1KOCl+2H2O+2e-=>2KClO3+2H2. And finally KClO3+H2O+e-=>KClO4+H2.

 

In order to facilitate these reaction you will need a corrosive proof cathode such as titanium, platinum. A few AA or AAA batteries should do for power and remove the need for a limiting resistor. Finally you will need to let the reaction cell go for several days and replace the batteries as they get low. This is because to transform a single Kcl molecule to KCLO4 will require 4 electrons and you’ll most likely b dealing with trillions of Kcl molecules. Please don’t do anything stupid with the KCLO4 mixing it with sugar is fine, a few grams of flash powder maybe, but don’t mess with phosphors or CaC2(absolutely do not mix it with sulfur as it can react with unreacted KOCL or KClO3.

[woelen]

When an ionic compound dissolves in water it dissociates into it’s component ions in this case K+ and Cl-. As opposites attract the K+ is pulled to the cathode and the Cl- to the anode where its oxidized to Ocl (hypochlorite)

This is not true. It is oxidized to Cl2. At the cathode, water is reduced to H2 and OH(-). Only by good mixing, the Cl2 and OH(-) react to form ClO(-). Here is problem #1. The mixing in practical setups can be a serious problem. Chlorine gas tends to bubble out of solution.

 

the net reaction being Kcl+H2O+e-=>KOCl+H2. Next the same thing happens oxidizing the hypochlorite to chlorate 1KOCl+2H2O+2e-=>2KClO3+2H2

Again this is not true. The hypochlorite disproportions to chlorate and chloride, but it only does at acceptable speed at elevated temperature. The hypochlorite does:

 

3ClO(-) ---> 2Cl(-) + ClO3(-)

 

The Cl(-) then again can be oxidized to Cl2 at the anode.

 

 

. And finally KClO3+H2O+e-=>KClO4+H2.

This reaction only happens with great difficulty. As long as there is some chloride left, the formation of chlorine is strongly favored, even when only a small amount of chloride is left. Besides that, formation of oxygen and acid at the anode becomes more and more a problem.

Formation of perchlorate requires high current density at an inert anode. Even Pt-anodes are corroded severely under these conditions. A good anode is a RuO2-anode (usually Ti-metal covered by RuO2).

 

In order to facilitate these reaction you will need a corrosive proof cathode such as titanium, platinum.

The cathode is not that important. As long as a voltage is applied the cathode is protected, due to the strong negative potential at the cathode. Any cathode will do, but best results are obtained with cathodes, which also withstand the conditions of the cell for a some time, when no voltage is applied. A nickel cathode, or a titanium cathode are perfectly suitable, but if nothing else is available, even copper wire or stainless steel could do the trick, provided they are not allowed in contact with the liquid, when no voltage is applied.

 

For the anode, titanium is totally useless. It erodes quickly and no chlorine is produced at all. You get a flocculent precipitate of hydrous TiO2 with that. For chlorate production, Pt is very nice, but graphite also could be used.

 

A few AA or AAA batteries should do for power and remove the need for a limiting resistor. Finally you will need to let the reaction cell go for several days and replace the batteries as they get low.

Such small batteries are TOTALLY useless for chlorate production, let alone for perchlorate production. You need a sturdy power supply, capable of delivering plenty of current for prolonged times. Even at 7 A you only obtain at most 1 mol of KClO3 per 24 hours. Something which does work is a good lab power supply. You do not need such a fancy one with variable voltage and current regulation. A fixed voltage device can be used perfectly. If you don't want to spend much money, you could modify an old PC powersupply, often they can be obtained for free.

 

http://woelen.scheikunde.net/science/chem/misc/psu.html

 

If you don't want the hassle of modifying a PC powersupply, then something like this is suitable (you should be able to find something like that for around $50):

 

http://www.rigpix.com/psu/propower_ps1310.htm

 

It is not a state of the art power supply, but for the electrolysis it is perfectly suitable. With this, you also need a resistor network for current control, but that need not be a problem.

 

This is because to transform a single Kcl molecule to KCLO4 will require 4 electrons and you’ll most likely b dealing with trillions of Kcl molecules.

For each mol of KClO3 you need at least 6 mols of electrons.

For each mol of KClO4 you need at least 8 mols of electrons.

 

In practice you need more, due to back-reduction at the cathode, where hypochlorite or chlorate is reduced back to chloride.

[bob000555]

The formulas you provided work if completely ignore the anion and the hydrogen in the h20.