Sciocrat
Harmless
Posts: 36
Registered: 30-3-2007
Member Is Offline
Mood: Scientifically curious
|
|
Separating KClO3 from KCl
I made some potassium chlorate by reacting a solution of potassium carbonate (0.180 mol) with chlorine (0.180 mol), made by reacting potassium
permanganate (0.072 mol) with conc. hydrochloric acid (0.576 mol). Chlorine was slowly bubbled into the K2CO3 solution, over a period of about 30-45
minutes. After the reaction, there was some crystallized solid on the walls of the beaker (probably KCl?), so I added some water to dissolve the
solid. Then I left the solution in the fridge to lower the temperature as much as possible. After 24 hours, there was a disappointing amount of
crystals sitting on the botom of the beaker - I guess I added to much water after the reaction. Later, I decided to evaporate the solution, and I got
about 28.8 grams solid material (KClO3 mixed with KCl, probably in roughly 22:7 ratio). Now I am trying to figure out how to separate these two
products, so I would be glad if someone could provide some advice...
Tnx in advance
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
Sciocrat's Old Fashioned Chlorate! I don't think anyone has used this method for about 150 years. 
First of all, does it still smell like chlorine? Did you boil it at all? You may have a lot of hypochlorite in solution. I suppose it's a moot
point now since you evaporated it.
KCl is about 10 times more soluble than KClO3 at cooler temperatures (under 40°C let's say), washing will suffice.
Tim
|
|
|
Sciocrat
Harmless
Posts: 36
Registered: 30-3-2007
Member Is Offline
Mood: Scientifically curious
|
|
I didn't find much information about this procedure on the internet, so I did assume that it is used rarely  However, I found the procedure interesting and wanted to give it a try.
The product does have a chlorine like smell, and it is definitely stronger then the smell of KClO3 I got by thermal decomposition of sodium
hypochlorite. I don't know if pure KClO3 smells like chlorine, but assuming it doesn't, I guess that the chlorate that I got from NaClO decomposition,
also haves some hypochlorite left in it (however, not enough to cause any unwanted effects, at least not when using it in pyrotechnic compositions).
Regarding the procedure, I brought the K2CO3 solution to boil lightly, and then started generating chlorine that was bubbled in the solution for some
time (while the solution was still kept at boiling temp). By the end of the procedure I added some water to dissolve a small amount of product that
crystallized (probably because of the loss of water during the reaction, and because of the fact that both products (KCl and KClO3) are much less
soluble than K2CO3). I boiled the solution for few more minutes, and then left it to cool.
Theoretically, from 0.180 mol K2CO3 (25 g), the product should contain 0.3 mol KCl (22.3 g) and 0.06 mol KClO3 (7.3 g). I will probably just add about
80 ml of 0°C distilled water to the product. This amount of water, at the given temperature, should be enough to dissolve most of the KCl, but
unfortunately it will probably dissolve some KClO3 too, although not more then 2-3 grams. So in the end, I expect 4-5 grams of KClO3. I will post
results when i'm done.
|
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
