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Author: Subject: The Short Questions Thread (4)
j_sum1
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[*] posted on 6-1-2016 at 16:46


Quote: Originally posted by The Chemistry Kingdom  
Is it possible to obtain hydrogen peroxide from sodium persulfate

If you know the answer please reply I am cuurently looking at alternative methods for obtaining hydrogen peroxide because it is a bit costly

I was wondering about this a couple of days ago. I hadn't gotten to looking it up though.
If there is an answer, I would love to know it.




In answer to my own question. Arrowroot is a good soluble starch.
Ingredients: Tapioca Flour
Contains sulfites


I managed to get half a teaspoon to dissolve in less than 100mL of water. It is slightly cloudy but no sediment has formed overnight.




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[*] posted on 6-1-2016 at 17:49


In regards to the persulfate, I know it works because it came up in an electrolysis book in the SM library. Sorry, I can't provide a reference as it is late.



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[*] posted on 7-1-2016 at 01:19


for H2O2 maybe use sodium percarbonate ?
OTC OxiClean, Oxy Clean etc. non-bio whitener
(bleach, e.g. 2Na2CO3.3H2O2 → 2Na2CO3 + 3H2O2 ,when added to water)
better to buy 'pure' sodium percarbonate as the OTC is 15% to 30%

EDIT e.g. http://www.ebay.co.uk/itm/172032224041?_trksid=p2060353.m143...

[Edited on 7-1-2016 by Sulaiman]
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[*] posted on 7-1-2016 at 02:18


I want to grow sulfur crystals from toluene solution
What do you think is the best technique?
Cooling heated solution or slow vaporisation of toluene ??
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j_sum1
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[*] posted on 7-1-2016 at 02:33


Quote: Originally posted by crystal grower  
I want to grow sulfur crystals from toluene solution
What do you think is the best technique?
Cooling heated solution or slow vaporisation of toluene ??

I did it with xylene a couple of months ago. Pix are in the pretty pictures thread.

Procedure was simple. I heated the xylene in a beaker and stirred in sulfur as it heated. At about 110C I had a nice yellow solution with a lot of S in it. Maybe 40% by mass. Crystals grew as it cooled.

Interested in your results. Mine were long needles. I think toluene gives a more regular shape.




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[*] posted on 7-1-2016 at 06:48


Quote: Originally posted by j_sum1  
Quote: Originally posted by crystal grower  
I want to grow sulfur crystals from toluene solution
What do you think is the best technique?
Cooling heated solution or slow vaporisation of toluene ??

I did it with xylene a couple of months ago. Pix are in the pretty pictures thread.

Procedure was simple. I heated the xylene in a beaker and stirred in sulfur as it heated. At about 110C I had a nice yellow solution with a lot of S in it. Maybe 40% by mass. Crystals grew as it cooled.

Interested in your results. Mine were long needles. I think toluene gives a more regular shape.

Thanks for answer .
Aren't long needles more likely caused by high temperature than by type of dissolvent ??

[Edited on 7-1-2016 by crystal grower]




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[*] posted on 8-1-2016 at 17:27


have crude, dark KOH from oak ashes--decolorizing advice?



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[*] posted on 8-1-2016 at 19:14


Quote: Originally posted by arkoma  
have crude, dark KOH from oak ashes--decolorizing advice?


What you have is crude, dark K2CO3 from oak ashes.

Oak ashes don't contain any KOH, mainly K2CO3.

Try active charcoal or a bit of hydrogen peroxide to get rid of the brown stuff.


[Edited on 9-1-2016 by blogfast25]




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[*] posted on 9-1-2016 at 12:11


Thanx Blog. So to get KOH:

K2CO3 + HCl then electrolyze the resultant salt?

It was throwing me because of the high pH and the fact the leachate is referred to as "lye".




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[*] posted on 9-1-2016 at 12:36


Quote: Originally posted by arkoma  
Thanx Blog. So to get KOH:

K2CO3 + HCl then electrolyze the resultant salt?



Easier: react it with slaked lime:

Ca(OH)2(s,aq) + K2CO3(aq) === > CaCO3(s) + 2 KOH(aq)

Filter off CaCO3.




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[*] posted on 9-1-2016 at 15:57
Ordering 1st ground glass joint glassware


I'm ordering my 1st ground glass joint glassware. It will be Chinese made( all I can afford right now) I know it's not the best, but I have a question. Should I go with 24/29 or 24/40 joint sizes both seem to be about the same in pricing? I know that 24/40 is suppost to be the best, But there does seem to be more variety in the 24/29 joint sizes. Just ordering a distillation kit and a vacuum filtering kit.
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[*] posted on 9-1-2016 at 15:59


It doesn't really matter, both are pretty much interchangeable.
If you really want to pick one, pick the one most used in your region. (US or Europe?)




all above information is intellectual property of Pyro. :D
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[*] posted on 9-1-2016 at 16:45


I like 24/40. I think it gives a more robust joint. I have a little 24/29 and have not had any compatibility issues.

One advantage of the larger size: I chipped the edge of a flask. It is still usable. With a smaller joint there would have been insufficient surface left to make a join.




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[*] posted on 11-1-2016 at 20:26


I recently obtained some pool sanitiser -- active ingredient lithium hypochlorite.
On reading the MSDS I have found that it is only 30% LiOCl with the remainder, "alkaline components". A flame test gives the characteristic colour of sodium -- sufficient to mask any Li to the naked eye. I am going to guess in the absence of better information that the additional compound is either sodium hydroxide or sodium carbonate. I intend some stage soon to do a titration to determine how much hypochlorite is there.

Any suggestions on how I might best determine the composition of what I have and also how to obtain a relatively pure lithium compound from this mix?




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[*] posted on 12-1-2016 at 11:00


Is there any book or something where I can check a substance's important proprierties like...toxicity?Especially related to nitro groups and single/triple bonds.

[Edited on 12-1-2016 by Tabun]
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sad.gif posted on 12-1-2016 at 22:12
Sources of Phosphorus?


I would like to know about any other sources of phosphorus besides matchboxes. There is a website called onyxmet.com. I ordered a few grams of red P to make phosphorus tribromide,which I ultimately used for methyl bromide. Since I will likely be visited by police if I try to order any more phosphorus,I would like to know about any possible sources of P besides scraping matchboxes.

[Edited on 13-1-2016 by CitricAcid]
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[*] posted on 12-1-2016 at 22:16


See the thread on making phosphorus using an aluminothermic reaction.
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[*] posted on 13-1-2016 at 10:51


Why on earth would you use PBr3 for methyl bromide. A mixture of methanol, sulfuric acid, and NaBr is quite sufficient.
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[*] posted on 14-1-2016 at 03:15


An answer
Quote: Originally posted by The Chemistry Kingdom  
Is it possible to obtain hydrogen peroxide from sodium persulfate

If you know the answer please reply I am cuurently looking at alternative methods for obtaining hydrogen peroxide because it is a bit costly
Quote: Originally posted by The Volatile Chemist  
In regards to the persulfate, I know it works because it came up in an electrolysis book in the SM library. Sorry, I can't provide a reference as it is late.


I have done a bit of research on this. See this thread and the resource I added.
http://www.sciencemadness.org/talk/viewthread.php?tid=16151&...



Another answer
Quote: Originally posted by kemster90  
Is there a chemical which can decompose bleach into oxygen without being consumed like maganese dioxide for sodium chlorate


You can use CoCl2 as a catalyst. The hypochlorite will decompose quite readily liberating wet O2 gas. I don't think much Cl2 is liberated in the process -- certainly not enough to smell.
If you are careful to not let the container overflow, then you can attempt to recover the CoCl2.




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[*] posted on 14-1-2016 at 16:30


Quote: Originally posted by j_sum1  
Soluble starch

I have searched the forum and a few other places but have not found good answers to this question.
I am after some soluble starch for use in redox titrations. I know I can buy some from a chemical supplier but I was wondering about otc sources and preparations. I didn't think it would be too hard -- in fact, it is probably so basic that no one writes much on it. Here is what I have tried and my thoughts so far.

1. I have thus far used white rice and washed it with cold water and collected the water from it. This has been somewhat successful in the past but my last attempt produced something that was not sensitive enough. I have also used hot water but always gotten a cloudy mixture that was not really any better for the task.

2. I have read a few very simple procedures for obtaining potato starch. Basically juice a potato and dry it. I am not sure how good this would be for iodometry. It is usually presented as a the first step in making a simple plastic product. I think that the starch obtained is quite soluble though.

3. There are quite a number of starchy products available at the supermarket. What the Americans call cornstarch is called cornflour here and I am not sure how it is processed or how it will act. Again, it is not that soluble. Arrowroot seems like it would be a better option. Alas, old-fashioned laundry starch has been replaced by ezi-iron.

4. There are numerous papers available that describe ways of making starch more soluble. There are modified starches. There are procedures for separating it from gluten and other proteins. It can be made into pre-gelatinised starch through a laborious process of soaking in DMSO and then baking for a long period. There is also the possibility of treating it with alkali or "a salt" to make it more soluble. I am not sure how one then effectively gets rid of the alkali or salt or even if it matters too much. I guess if I used ammonia then any excess would evaporate away.


So, (and I know I am probably overthinking this) what is the best course of action? Is juicing a potato ok? Or should I buy some tapioca flour? Is it worth treating it in any way? Or is best to spend a couple of bucks at a chem supplier?


did you see this: https://www.youtube.com/watch?v=rypuMg-r3zM?
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[*] posted on 14-1-2016 at 16:59


Thanks HeYBrO.
That is a cool procedure with the glycerine. I have found that arrowroot is pretty soluble and seems to work quite well. I wonder if I could get an even better product by combining the two approaches.

I also bookmarked that channel. It seems that there is quite a bit of good stuff there. Might be a language barrier in places however.




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[*] posted on 14-1-2016 at 20:06
How do I identify ammonium bisulfate vs ammonium sulfate (has it converted to bisulfate)


When I was working on purification of Amm Sulfate, I wasn't aware that it would decompose to bisulfate at 212F. I allowed a pot of water/amm sulfate solution to reach boiling and then evap'd some in an open glass dish at a temp above 212 (about 350 in oven actually). I had misread the properties of sulfate and didn't know about this on my first run and in the middle of second.

I'm curious if everything in the pot that was in solution would have decomposed into the bisulfate or if it should be alright. Also what about the part that was evap'd at 350.

I've tried finding info about the bisulfate and there is very little info about it and it's uses.

I can say that I noticed VERY little ammonia smell at any time during this process. I would say that the scent from a single spray of Windex would have smelled stronger and lasted longer than the boiling and I noticed no smell during evap.

I would think that since the bisulfate looses 1/2 the ammonia per weight then I would have had a pretty strong smell of ammonia when doing this.

What do you guys think? Is there a way to test this?
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[*] posted on 14-1-2016 at 20:11


If you dissolve some in water, ammonium bisulphate will be much more acidic than ammonium sulphate.



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[*] posted on 14-1-2016 at 20:54


Quote: Originally posted by DraconicAcid  
If you dissolve some in water, ammonium bisulphate will be much more acidic than ammonium sulphate.


Yes, and then you could neutralize it with ammonia and be back to ammonium sulfate.




Any other SF Bay chemists?
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[*] posted on 16-1-2016 at 07:57
Removing water from Ammonia Cleaner


I was thinking about how corn meal is used in removing the last bit of water from alcohol, I think I have read that things like anhydrous MgSO4 can be used as well.

Could either of these be used to absorb water from a standard ammonia cleaning solution?
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