binaryclock
Hazard to Others
Posts: 121
Registered: 9-4-2013
Location: Canada
Member Is Offline
Mood: Organic
|
|
Metathesis of KClO3 from NaCLO3
Hello:
I've recently created a batch of crystals of NaCLO3 that were in electrolysis cells for three days in a solution of NaCl.
After three days, I boiled the solution to remove any hypochlorates and then added the same amount of KCl to the mixture and allowed it to perform
metathesis. Some crystals formed immediately and sank to the bottom. After a while I took the solution and put it in the freezer to about 0c. At
0c, almost half the beaker was filled with crystals so I harvested them by decanting the liquid solution and putting the crystals on filter paper to
dry.
Once dry, when burned the flame was yellow/red. It was not purple like my KCl syth crystals. It seems that I have more NaCLO3 than KCLO3 in my yield
from the NaCl cell. What did I do wrong here?
Now that I have about 40g in dry crystals, how should I best go about getting them converted to KClO3 crystals?
Thanks
Current Project: Playing with my new Laboy advanced distillery kit!
|
|
|
chemcam
Hazard to Others
Posts: 423
Registered: 18-2-2013
Location: Atlantis
Member Is Offline
Mood: I will be gone until mid-september, on a work contract.
|
|
Even a small amount of NaClO3 contamination will discolor the flame of KClO3 you most likely have more K than Na so I would take advantage of their
different solubilites and do a 0C water wash. You will lose some product but gain purity.
|
|
|
binaryclock
Hazard to Others
Posts: 121
Registered: 9-4-2013
Location: Canada
Member Is Offline
Mood: Organic
|
|
Thanks for your reply. I'll try that tomorrow and see how it goes. I wasn't aware that a small amount of NaCLO3 discoloured the flame.. thanks for
the info!
Current Project: Playing with my new Laboy advanced distillery kit!
|
|
|
ScienceSquirrel
International Hazard
Posts: 1863
Registered: 18-6-2008
Location: Brittany
Member Is Offline
Mood: Dogs are pets but cats are little furry humans with four feet and self determination! 
|
|
Sodium floods everything in flame tests, your product could be at 99% pure and the sodium would still show up.
http://chemistry.about.com/od/analyticalchemistry/a/flametes...
|
|
|
binaryclock
Hazard to Others
Posts: 121
Registered: 9-4-2013
Location: Canada
Member Is Offline
Mood: Organic
|
|
Cool thanks for the link. Scumbag sodium 
Current Project: Playing with my new Laboy advanced distillery kit!
|
|
|
hyfalcon
International Hazard
Posts: 1003
Registered: 29-3-2012
Member Is Offline
Mood: No Mood
|
|
That's why many of us start with KCl when we want the end product for use in pyrotechnics. If the sodium is never there then it can't ruin the show!
|
|
|
phlogiston
International Hazard
Posts: 1376
Registered: 26-4-2008
Location: Neon Thorium Erbium Lanthanum Neodymium Sulphur
Member Is Offline
Mood: pyrophoric
|
|
Fortunately, the solubilities of KClO3 and NaClO3 work in your favor:
1. good recovery
KClO3 solubility varies strongly with temperature and it is only moderately soluble in cold water, so the recovery of recrystallizations is quite
good.
2. Big difference beteen solubility of NaClO3 and KClO3
NaClO3 is -very- soluble, even at low temperatures, so it is doable to get rid of even small impurities of NaClO3. For best results, use suction on
filtration (buchner filter works very well) to remove recrystallisation liquor and wash once/twice with ice-cold water in the filter.
-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
There's a thread on converting NaClO3 (used to be in some weed killers) to KClO3 on this forum.
|
|
|
Fantasma4500
International Hazard
Posts: 1677
Registered: 12-12-2012
Location: Dysrope (aka europe)
Member Is Offline
Mood: dangerously practical
|
|
i would say even just using cloth for filtration and then squeezing it would be enough, a neat little tip is to take tissue paper, fold filter in half
and suck the water out of both the insoluble and the filter with the dry tissue paper
this can be done with normal filter paper ofc.. very very handy especially if you can combine that with ether then you could do it in literally less
than 10 mins
in short
squeeze out the liquid of the filter, or scrape the crystals onto tissue paper and let them dry, then you shouldnt need to purify it further by
recrystallization
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
