Varmint
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Where did I go wrong (KClO --> KClO3)
I did the poor man's KClO<sub>3</sub> production, boiling down until crystals of NaCl just started to fall out, removed from heat, let
cool, then poured off the liquor into a fresh beaker.
I repeated the procedure a second time in order to have a larger volume to work with. Once the second batch had cooled, I added the liquour to that
from the first batch. (Label Volume2)
To that I added an equal volume of saturated KCl solution, stirred, and was rewarded with a sizeable crop of presumed KClO<sub>3</sub>
that precipitated out, which I filtered, keeping the crystals, discarding the liquor.
Recognizing the still appreciable smell of hypochlorite on the still wet crystals, I decided to clean the beaker, add the crystals back, add the same
amount of [distilled] H<sub>2</sub>O to get back to Volume 2, covered with a watch glass, and boiled for 15-18 minutes.
The solution lost virtually all of the hypo smell, but here's what I don't understand. At virtually the same volume, absolutely NONE, zero,zip,nada
crystals fell out of solution.
I was expecting a loss in precipitate (figuring the missing NaCl left more "room" for KClO<sub>3</sub> ), but nothing.
So, did I destroy some KClO<sub>3</sub> by the boiling, or did the not missing NaCl really leave that much more room for
KClO<sub>3</sub> and all I need to do is boil off some more water to get my (lowered) yield back?
Did the remaining NaClO "eat" my KClO<sub>3</sub>?
I know this is something fundamental I'm missing, but I can't see what caused the apparent loss.
Even more perplexing is I did this sucessfully once before, but instead of trying to boil off the NaClO, it simply let the crystals dehydrate and the
NaClO smell disappeared in sort order. I was then able to recrystalize the KClO<sub>3</sub> 2 passes, with better purity and prettier,
larger crystals each time.
Thanks for any insight.
DAS
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: corrected
formulæ]
[Edited on 2.8.13 by bfesser]
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Pulverulescent
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| Quote: | | I know this is something fundamental I'm missing, but I can't see what caused the apparent loss. |
Bleach weaker than advertised ─ interfering contaminants ─ lowered pH . . . take your pick . . .
NaClO3 is still available as weedkiller, AFAIK, albeit with added fire suppressant which might be separated by selective crystallisation!
"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones"
A Einstein
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Varmint
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Exact same bleach (same bottle), the disinfecting variety with "double the strength".
So, it's not the starting material, but something in my process that killed the KClO<sub>3</sub>.
DAS
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: corrected
formula, removed unnecessary quote(s)]
[Edited on 2.8.13 by bfesser]
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SM2
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Concentrate on your solubilities. Especially as it comes to KClO<sub>3</sub> in cold H<sub>2</sub>O. Now, you can buy USP
grade KCl pellets from the home Depaux for <$10 for like 50Lbs. KClO<sub>3</sub> really is not very soluble in freezing cold water.
Use this to your advantage. You might consider switching to high test hypochlorite (H-T-H) from pool supplies. I've made lots of
ClO<sub>4</sub><sup>-</sup> and ClO<sub>3</sub><sup>-</sup> using only either
<del>salt</del> [NaCl] or KCl, and a bunch of 150W solar panels. The electrodes were Ti plated. Really, it's worth it to just order 5-10
K
lbs KClO<sub>4</sub>. Hope it helps.
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: corrected
formulæ]
[Edited on 2.8.13 by bfesser]
"Old men who speak of victory
shed light upon their stolen life
they - drive by night- and act as if they're
moved by unheard music." B. Currie
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bbartlog
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Without quantities, it's hard to say whether what you're seeing is supersaturation or just the fact that you no longer have the competing ion effect.
As you suggest, there is 'more room' for KClO<sub>3</sub> to dissolve when you use distilled water rather than a saturated solution of
KCl. But whether this is enough to account for what you've seen depends on the mass of KClO<sub>3</sub> and the volume of the liquid that
was added. I would suggest that if you want to do something like this again, you should weigh the crude product and look up a
solubility-versus-temperature chart so that you can estimate a roughly appropriate amount of distilled water (or other solvent) for recrystallization.
Anyway, it seems highly unlikely to me that your potassium chlorate was destroyed.
The less you bet, the more you lose when you win.
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Varmint
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bbartlog:
Got to be the competing ion issue. I'll just boil away some more H<sub>2</sub>O and see where that gets me.
SM2:
Your home depot is beter than mine! something like $22 for my 40lb bag (all softener salts seem to be 40lb qty here).
But when you figure the KCl + almost free electricity (by comparison to the chemistry) I can end up with some really good yields and high purity with
none of the waste when my Pt clad [n]iobium screens get here!
I'll do the two tank route, 1st cell with chlorides always above 5g/100ml to preserve the anode, and I'll be recrystalising the
KClO<sub>3</sub> before it goes in the KClO<sub>4</sub> cell.
Also going to try the KClO<sub>3</sub> + Heat --> KClO<sub>4</sub> path to see how that works out...
thanks,
DAS
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: corrected
formulæ]
[Edited on 2.8.13 by bfesser]
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Pulverulescent
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IIRC, thermal disproportionation of NaClO3 is notoriously slow and difficult to drive to completion!
OTOH, the ClO4 salt itself, is fairly pricey!
"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones"
A Einstein
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Fantasma4500
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im not sure if you wrote that you did try to cool it down, in which is the most beatiful and yield increasing step in this procedure, cant tell if the
capitalization of the chemical formulas was too confusing (i have never witnessed NaCl written as NACL before, very new to me, lol)
as you recognize words by their shape when you read fast, i think its a must to write chemical formulas with correct capitalization..
anyhow..
when you add the KCl, boil it down again until you see NaCl crystals form, then add a littlebit of water to remove this effect, as NaCl does
precipitate in small amounts when you cool it
cool the whole solution as much as possible and filter
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Varmint
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Formulas:
Depends on the forum I guess. Early on in many or most chem forums since subscript was nigh to impossible, folks just adapted and used all caps and
didn't even bother with trying to subscript.
If this forum's preference is proper - NaCl - then I'm good to go, but keep in mind in the distant past I was chided for using that very smae thing.
Now all I've got to do is figure out subscript here...
With the BBS SW do it for me? (Test) KNO3 H2SO4
DAS
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bfesser
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I don't know what forums you speak of, but that's very unscientific and just plain wrong. Use proper notation, or you're going to anger a lot of
people (particularly me!). Quote: Originally posted by bfesser  | I feel that there's now no excuse not to use subscript and superscript in posting. Some time ago, I coded up some buttons that you will see on the
"Post Reply" page under the "Text Color:" dropdown (<strong>x<sub>y</sub></strong> and
<strong>x<sup>y</sup></strong> , and <a
href="viewthread.php?tid=18651#pid242812">Polverone was gracious enough to fix my errors and implement them</a>. For those who can type
BBCode tags, you can use [sub][/sub] and [sup][/sup]. Or for HTML junkies like
myself, use <sub></sub> and <sup></sup>.
<strong><a href="viewthread.php?tid=15528#pid201809">Subscript</a></strong> thread |
It's easiest to just type the tags out by hand, but you can also use these buttons: <img src="./images/xpblue/bb_subscript.gif"
/> and <img src="./images/xpblue/bb_superscript.gif" />
[edit] Please stop writing HOH. I'm sorely tempted to just trash those posts...
[Edited on 2.8.13 by bfesser]
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Varmint
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OK, let me try this out...
H<sub>2</sub>SO<sub>4</sub>
Well, I can see I'm going to want to keep a notepad doc with common formulas open while posting because that's just not fun enough to do manually
every time, and if people are going to actually get angry, well we wouldn't want to upset the apple cart.
DAS
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bfesser
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You get used to it. I can type out entire reaction equations properly formatted, about as quickly as I can type out a regular English sentence. I
don't expect anyone else to be able to do this, of course, but a little effort would be nice. Thanks for your willingness to adapt, it's greatly
appreciated.
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Varmint
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I'm adaptable! <del>You've since corrected SM2's use of HOH which is where I picked it up from, normally I woud have put H2O.</del>
But now it will be H<sub>2</sub>O from here on out.
I use HTML quite a bit actually, I write a lot of HTAs but the tags generally apply to whole lines or table cells, having to bounce around within a
word would make me batty, ergo my notepad helper doc is already under construction...
DAS
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: del]
[Edited on 2.8.13 by bfesser]
OK, so I jumped the gun.
Following a nice boil-down, I got back what looks to be a sizeable percentage of my expectation.
So, as bbartlog mentioned, it had to be the competing ion effect.
Since the liquor volume was so low I decided to use a graduated cylinder to watch the precipitation. Interesting to watch the size of the crystals
grow then diminish as the cylinder cooled.
Thanks for all the input, positive and corrective!
DAS
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: merged
sequential posts]
[Edited on 2.8.13 by bfesser]
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TheChemiKid
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| Quote: Originally posted by Varmint | Exact same bleach (same bottle), the disinfecting variety with "double the strength".
So, it's not the starting material, but something in my process that killed the KClO<sub>3</sub>.
|
Did you check the MSDS to see if anything else was added as a stabilizer that might change the reaction (such as phosphoric acid or sodium hydroxide)?
When the police come
\( * O * )/ ̿̿ ̿̿ ̿'̿'̵͇̿̿з=༼ ▀̿̿Ĺ̯̿̿▀̿ ̿ ༽
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ElectroWin
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the whole procedure from second batch onward, seems borked.
you should be washing with a saturated solution of your desired product, KClO3, not of KCl.
please check and review the principles behind washing crystalline product.
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hyfalcon
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Since KClO3 has such a low solubility at cold temperatures, what he should be washing with is ice cold distilled or at least deionized
water. This will help strip any sodium ions left from the metastasis reaction.
[Edited on 10-8-2013 by hyfalcon]
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ElectroWin
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ok, must be ice cold KClO3 solution, then
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hyfalcon
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Not if you are wanting to strip the remainder of the sodium ions left over from the metastasis reaction. There needs to be some room in the solution
to do this. Look up the solubility curves for KClO3. You will loose very little at 00C.
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ElectroWin
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there is plenty of room for sodium to be taken up, even if the solution is saturated with KClO3. please look at
http://www.tannerm.com/images/solution1.gif
[Edited on 2013-8-12 by ElectroWin]
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hyfalcon
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You get a cleaner product by stripping with an unsaturated solution. That's all I'm gonna say about it.
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ElectroWin
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either way, the wash solution you use must remain unsaturated w.r.t. the small number of NaCl crystals you have in your product, (and enough volume to
dissolve all of those).
the reason to use a wash solution saturated with your desired product is so that you will not lose any of your desired product into the solution.
instead, the NaCl, being more-soluble than KClO3, will replace it in solution. i believe this principle is well established in the literature, and is
particularly effective for countercurrent extraction.
fyi, you can extrapolate from
http://www.freepatentsonline.com/3278275.pdf
[Edited on 2013-8-12 by ElectroWin]
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hyfalcon
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Anything that comes from that wash I recycle back to the cell for replacement electrolyte.
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AJKOER
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One path to Chlorate formation from NaOH (or KOH or Ca(OH)2...) requires high ionic strength, high pH and just mild heat (75 C).
Here is a design I am considering:
1. Place hot NaOH flakes (or be able to mildly heat) at the bottom of a large wide mouth container.
2. Place and start a Cl2 generator, from say, adding NaHSO4 to a solution of H2O + NaOCl + NaCl (chlorine bleach), in its own vessel in the large
container.
3. Close/seal the large container and place in a tray of hot water.
Reactions:
In the Chlorine generator:
NaHSO4 + NaOCl --> Na2SO4 + HOCl
NaHSO4 + NaCl --> Na2SO4 + HCl
HCl + HOCl = Cl2 (g) + H2O
In the large vessel:
6 NaOH + 3 Cl2(g) --> NaClO3 + 5 NaCl + 3 H2O
Note, any pressure buildup in the container will help push the reaction to the right.
Reference for the last reaction: See section 5.14.2 at http://www.docbrown.info/page07/redox2.htm.
-------------------------------------------------------------------
Here is a path that I have actually done that requires first, however, the preparation of a soluble Silver salt.
1. Prepare Silver acetate from slowly dissolving Ag source in a solution vinegar and H2O2 over a period of days. Leave the salt in its Acetic acid
solution.
2. Add NaOCl. If Chlorine Bleach is your source of hypochlorite, you will also be adding NaCl and possibly Na2CO3 depending on the brand of the
bleach.
3. Filter out the white insoluble AgCl (that is formed immediately!) leaving a solution of just AgClO3. Note, any NaCl present will also generate
Silver chloride so use sufficient Silver acetate.
Now, if you want KClO3 add KOH (or KCl). Filter again to remove new formed Ag2O or AgCl. Cool or evaporate to separate out your largely chloride-free
chlorate salt.
Do not throw out the AgCl as it can be combined with sugar and NaOH to reclaim the Silver.
[Edited on 14-8-2013 by AJKOER]
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