3 replies to this topic

[overflow]

Hi all,
on the internet i've found many how-tos but i never found a chemical explenation, so i tried my own, correct me if i'm wrong.

Molecular weights:
H20 = 18 uma
NaClO = 74 uma
NaClO3 = 106 uma
NaCl = 58 uma
KCl = 74 uma
KClO3 = 122 uma

1 liter of 5% NaClO
1 liter of water -> 1000gr -> 56 moles of water
i'd guess (correct me!) that this means in a 5% solution there are 53 moles of H20 and 3 moles of NaClO

Thermal decomposition should follow this formula
3NaClO -> 2NaCl + NaClO3

So, every 3 moles you get one mole (122 grams) of NaClO3 and 2 moles (116 grams) of NaCl

We will now need 1 mole (74 grams) of KCl

NaClO3 + KCl -> NaCl + KClO3

Which will give us 1 mole (122 grams) of KClO3

Which isn't theorically too bad, but my calculations differ from those given here ( http://www.wfvisser....EN.html#thermal ) as he says to add only 28grams of KCl so i must be mistaken somewhere, but where?

Thanks!

[Mumbles]

The 5% is mass per volume, not molar percentages. So 1L of 5% NaClO has 50g of NaClO, not 3 moles, which is somewhere around 225g. So, now that you're off by a factor of approximatly 3 moles, the KCl discrepancy now makes more sense. They use an excess of KCl, so that is why the correction ratio isn't perfect.

[overflow]

The 5% is mass per volume, not molar percentages. So 1L of 5% NaClO has 50g of NaClO, not 3 moles, which is somewhere around 225g. So, now that you're off by a factor of approximatly 3 moles, the KCl discrepancy now makes more sense. They use an excess of KCl, so that is why the correction ratio isn't perfect.

Ah, thanks for the clarification!

The other day is tried to purify the chlorate i obtained (which had quite a bit of sodium residues) with the recrystallization method:
unlickily the chlorate had attached to the bottom of the pyrex container and didn't dissolve well in water.
As soon as i started heating it i started to hear quite a few micro-explosions and saw bubbles of gas (oxygen?) arising from the bottom.

The end product was a white powder which tends to clump alot together and doens't have any kind of oxidizer quality

My guess is that the concentrated heat at the bottom decomposed the chlorate into something else, maybe just in KCl :-/
Ideas?

Edited by overflow, 22 May 2007 - 05:05 PM.

[Bonny]

Ah, thanks for the clarification!

The other day is tried to purify the chlorate i obtained (which had quite a bit of sodium residues) with the recrystallization method:
unlickily the chlorate had attached to the bottom of the pyrex container and didn't dissolve well in water.
As soon as i started heating it i started to hear quite a few micro-explosions and saw bubbles of gas (oxygen?) arising from the bottom.

The end product was a white powder which tends to clump alot together and doens't have any kind of oxidizer quality

My guess is that the concentrated heat at the bottom decomposed the chlorate into something else, maybe just in KCl :-/
Ideas?

I made some KCL03 awhile back (before I found a source to buy it). I will get the info this weekend if you want. It was made by gently boiling KCL in 4l of household bleach for several hours until it read full on a battery charge meter. I'll post the details next week. I remember the yield being small, but the was likely due to my own error. However it did produce a nice blue colour when tested in a formula.