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Author: Subject: KClO3 Stoichiometry questions
Manifest
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[*] posted on 27-4-2014 at 13:12
KClO3 Stoichiometry questions


Hello, I am planning on doing the boil down bleach method however I am unsure whether to make an equally concentrated volume with KCl or to use the stoichiometric amount in a saturated solution.
(Nurdrage says use equal volume, MrHomeScientist says use stoichiometric amount)

I am unsure whether I am doing this correctly:
First off, the disproportionation:
3 NaClO → 2NaCl + NaClO3
I have 5% bleach and I plan to boil down a litre so 5% of 1000 is 50.
50 grams NaClO = 0.67 moles

So I divide that by 3 = 0.67/ 3= 0.22 moles
0.22388794856 moles to grams = 23.83 grams of NaClO3

Next reaction is
KCl + NaClO3 → NaCl + KClO3
23.83 grams = 0.22
0.22 moles of KCl = 16.69


and 27.43g of Potassium Chlorate produced.

Is this accurate? Because that is pretty shit for a litre of Bleach.




You guys are all jealous of my scales, take the green shades off.

[Edited on 28-4-2014 by Manifest]
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plante1999
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[*] posted on 27-4-2014 at 13:15


Looks very similar to the pratical results I had obtained in the past. Electrolysis is the way to go.



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[*] posted on 27-4-2014 at 13:27


Quote: Originally posted by plante1999  
Looks very similar to the pratical results I had obtained in the past. Electrolysis is the way to go.

And that is with 100% efficiency.
Electrolysis is in process. I run it from 9 in the morning from when I wake up to 10 and night, that reminds me...

It's been running for 2 days this way now at 1Amp, 6 volt

When I switch to 12 volts for a second I get 5 Amps.
I figured this would have decreased due to loss of sodium chloride, maybe not.

Anyway, should I keep being patient or how do I know when electrolysis is complete?
How much KCl do I add? Should 50g be sufficient?



[Edited on 27-4-2014 by Manifest]
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plante1999
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[*] posted on 27-4-2014 at 13:31


Depends on you exact set-up.

Electrolysis should be kept at 3.3 to 5 V for maximum efficiency, over that you degrade your anode more then anything else.





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Chemosynthesis
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[*] posted on 27-4-2014 at 13:41


Not to nag, but it's "Cl" rather than "CL." The latter hurts my eyes.
Edit- thanks. Also, I agree with Plante99; for both chlorate and perchlorate production, electrochemistry is the way to go. I recall some friends of mine way back using industrial strength reagents to disappointing effect.

[Edited on 27-4-2014 by Chemosynthesis]
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[*] posted on 27-4-2014 at 13:42


Apologies, that was due to fast typing.I only do it on K̶C̶L̶ KCl
Corrected.

[Edited on 27-4-2014 by Manifest]
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[*] posted on 27-4-2014 at 13:53


What am I doing wrong with your formula Plante?
As per your PDF

Time(H)= ((171.6/amp)x saltm)x %100

x= ((171.6/1)*1*35 = 6006 hours?

250.25 days? That can't be right.
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plante1999
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[*] posted on 27-4-2014 at 13:57


EDIT

I made a small mistake.

It appears I made a mistake in the equation I gave!

You should divide by the %. As such 35 become 0.35 and you divide instead of multiplying.

Total run time approx : (171.6/1) x 1 / 0.35 = 490 hours

490/24 = 20 days at 35% efficiency.

[Edited on 27-4-2014 by plante1999]




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[*] posted on 27-4-2014 at 13:59


No, I have got 1 Mole in my cell at a efficiency of 35%

EDIT
Oh, I see.
20 Days straight though, will I get a shit result if I continue until Sunday?

[Edited on 27-4-2014 by Manifest]
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plante1999
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[*] posted on 27-4-2014 at 14:13


It will need 20 days straight to turn one mol of salt into one mol of chlorate with pH control at 35% efficiency with one amp. By pumping two amp it would be two time as fast.



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[*] posted on 27-4-2014 at 14:30


Would I not be better to apply 6 amps or would that rip the anode apart?

Should I add acid to bring the PH down?
Would Vinegar work or is it too weak?

[Edited on 27-4-2014 by Manifest]
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plante1999
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[*] posted on 27-4-2014 at 14:41


Hydrochloric acid is better.

Depends on your anode, mmo will work at 0.2 amp per square cm of surface area. The killer is the voltage, not the amps usually.




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[*] posted on 27-4-2014 at 15:15


Quote: Originally posted by Manifest  
I am unsure whether to make an equally concentrated volume with KCl or to use the stoichiometric amount in a saturated solution.


There are situations where double salts can be formed with excess KCl but not here I think.

Calcium hypochlorite is the way to go, if you want lots and want it today.




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[*] posted on 27-4-2014 at 16:15


Here is some information on chlorate production stoichiometry:
http://www.sciencemadness.org/talk/viewthread.php?tid=28777&...
I agree with S.C. Wack that calcium hypochlorite is the most efficient method if you want it fast - not the cheapest, but the fastest.




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[*] posted on 28-4-2014 at 04:55


Quote: Originally posted by Manifest  
0.22388794856 moles to grams = 23.830857132675grams of NaClO3



Were they expensive, your picogram scales? :D




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[*] posted on 28-4-2014 at 05:14


No, I struck a special deal, I got them for free when I bought the Hadron Collider!:D
[EDIT] Ah, I thought you were talking to me, I used nearly the same figures in the link supplied above.

[Edited on 28-4-2014 by Zyklonb]




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[*] posted on 28-4-2014 at 05:58


Dang, that is one REALY ACCURATE scale there!

Say, can I borrow the Hadron collider on weekends if I pay the power bill?




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MrHomeScientist
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[*] posted on 28-4-2014 at 06:21


In my video I followed the procedure I'd seen elsewhere of combining equal volumes of boiled bleach and KCl solution, but as you mentioned I do think stoichiometric would have been better. Less water available for the chlorate to dissolve in should lead to better recovery. The only reason I can think of to have such a huge excess of KCl is maybe some sort of common ion effect further reducing solubility of the chlorate. I need to try this again with stoichiometric amounts.
I've also now done electrolysis, and it works very well. The bleach method is nice and simple, but if you have the apparatus for electrochemistry that's the way to go. I've only done one run for 24 hours, so I can't say anything about electrode life, but it went quite smoothly. It's nice to be able to just set it up and walk away while it does the work for you.
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[*] posted on 28-4-2014 at 10:17


Electrolysis is the way to go if you want a lot.
Don't use graphite unless you want to waist a lot of time and compromise the purity of the product. I am running a cell with MMO anodes currently, and I have plenty of MMO if you want to buy some.




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[*] posted on 28-4-2014 at 10:34


Quote: Originally posted by blogfast25  

Were they expensive, your picogram scales? :D


Haha you guys are assholes, I didn't feel like shortening it to two digits because I copy and pasted from the Google calculator.
It's more accurate anyways.
Yes, I know how to round off, Bert.

MrHomeScientist, did you record your electrochemical synthesis? I'd love to see it.


[Edited on 28-4-2014 by Manifest]
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[*] posted on 28-4-2014 at 11:42


We're the *ssholes? You don't think using numbers like that makes you look a bit silly?

Oh well...




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[*] posted on 28-4-2014 at 11:56


Unfortunately no I did not record it. I did the experiment as a last-ditch, emergency bid to make some chlorate I needed for a demonstration that weekend. So I really threw it together poorly and had little time to record and edit a video. Now that I know it works, though, I'll definitely produce a video on it.
I've made a commitment to myself that I'm going to do something in the lab every weekend. This is an effort to increase my YouTube posting frequency, but it doesn't necessarily mean a new video every week (though I'd love to do that). So far, the first two weekends have been taken up inventorying every one of my chemicals and developing a more organized and formal storage system. Turns out I have 155 unique chemicals in total!
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Manifest
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[*] posted on 28-4-2014 at 12:36


Quote: Originally posted by blogfast25  
We're the *ssholes? You don't think using numbers like that makes you look a bit silly?

Oh well...


assholes in a joking, non serious kind of way, don't take me literally.

I guess it does.

@MrHomeScientist
How much Chlorate did you obtain and what was your electrodes and what voltage and current did you apply?

Is chlorate better/worse/equal to KNO3 for pyrotechnics?


[Edited on 28-4-2014 by Manifest]
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[*] posted on 28-4-2014 at 15:48


Here are the stats on my thrown-together chlorate cell.

Anode: MMO mesh
Cathode: Ti mesh
Immersed elecrode area: ~3in2 (~19cm2)
Voltage: 4.8V
Current: 2.55A
Run time: 24 hours
Yield: 28.5g very crude, greyish product

Detailed write-up:
I made a solution of 78.3g KCl in 260mL distilled water. To this I added 0.3g potassium dichromate dissolved in 5mL distilled water. I poured about 210mL of the finished solution into a plastic Chinese take-out container (as I said, thrown together quickly and not intended to last), and acidified the rest with 0.5mL of 9.5M HCl and set it aside. I cut two slits in the lid of this container for the electrodes, and a small hole in the center to vent (this was done outside).
I only ended up adding 1mL of the acidified stock solution about halfway into the procedure, because the volume hadn't realy appeared to decrease at all. I immersed the container in a water bath, and the solution and bath were warm to the touch throughout.
After stopping electrolysis, I capped the container with a new lid and placed it in the fridge. After cooling and filtering off the liquid, I had 28.5g of product. This is extremely crude, and is a greyish-green in color. The grey color came from some powder that spalled off the MMO at the start of electrolysis, but the mesh doesn't appear degraded at all (it was the first time I had used it). Definitely needs a recrystallization.

I have no experience with pyrotechnics, but I've heard that you should avoid chlorate and use perchlorate instead, due to its decreased sensitivity.
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[*] posted on 28-4-2014 at 19:34


While the following disproportionation is widely promulgated:

3 HOCl ----) 2 HCl + HClO3

a commercial patent I have seen (see World Patent W091-03421-1, “High Purity Chloric Acid” , link http://www.google.com/patents/EP0490978A1?cl=en ) appears to imply the following scheme in a closed reaction:

3 HOCl ----) 2 HCl + HClO3
2 HCl + 2 HOCl = 2 Cl2 + 2 H2O
Net:
5 HOCl ----) 2 Cl2 + 2 H2O + HClO3

In other words, there is a possible loss of Hypochlorous acid to Chlorine so more likely around five moles of HOCl is required for each mole of HClO3 in a closed reaction chamber, and not three as is the common unqualified assertion.

[Edited on 29-4-2014 by AJKOER]
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