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Ramium
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Quote: Originally posted by blogfast25  | Gentlemen.
It does all depend a lot on the kind quantities one wants to produce. I prepared about 0.5 ml of wet bromine when I was about 15. I oxidised KBr and
collected the wet, undistilled Br2 with a small separating funnel. Enough to verify some its properties and to marvel at this dark liquid.
At such low quantities the risk to oneself is very small, especially if you still take the necessary care. |
i
just want a little sample for my element collection
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Ramium
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I will buy some condensing gear soon
I assume that is what i need
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diddi
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re glassware. there are a number of ebay sellers who offer organic chem sets and distillation sets. look on youtube for a demonstration of the Br
extraction (the ones that use gloves and fume hoods are prolly SM members). there is plenty of discussion about ebay sellers on SM
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Ramium
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Thanks heaps well have a look
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Texium
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The first time that I isolated bromine, I used 31% HCl with solid potassium permanganate and sodium bromide in a ground glass simple distillation
apparatus. It worked, but the yield was not great, and was contaminated with water. I used HCl because it was the only strong acid I had at the time.
Sulfuric acid is preferred because it absorbs whatever water is left in the mix and allows the pure bromine to distill over.
I was definitely not very experienced at the time that I did this, and it still turned out alright, so I'd say go for it if you're only trying to get
a few mL. It's not as dangerous as some make it out to be, and is fairly straightforward even if you don't have much experience. As long as you
understand the risks, listen to the advice of others (which it looks like you are), and take reasonable precautions, you should be fine. My own advice
to add is to just make sure that you're outside and well away from other people when you do it. Also, if it manages to escape the apparatus, don't try
to contain it, just stop what you're doing and get away from there until the fumes clear. If you go into panic mode in that scenario, that's when
you're most likely to get yourself hurt.
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blogfast25
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| Quote: Originally posted by zts16 | Sulfuric acid is preferred because it absorbs whatever water is left in the mix and allows the pure bromine to distill over.
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Care to explain that? Dilute H2SO4 doesn't absorb water.
Conc. H2SO4 does but cannot be used here because of the KMnO4 (possible formation of Mn2O7).
With a BP of 59 C the bromine can be distilled off easily.
Wet bromine can be dried further with conc. H2SO4, then distilled again if need be.
HCl isn't recommended here because KMnO4 can oxidise it to chlorine.
KMnO<sub>4</sub> + 8 H<sup>+</sup> + 5 e ==== > Mn<sup>2+</sup> + K<sup>+</sup> + 4 H2O
[Edited on 13-2-2015 by blogfast25]
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Molecular Manipulations
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You could probably get away with using ~85% sulfuric acid, which is still hygroscopic but most likely won't make much or any manganese heptoxide.
But potassium permanganate is not the best option, especially in combination with HCl (aq) as blogfast25 said.
I personally use 98% sulfuric acid and 35% hydrogen peroxide, I've found nothing that works better so far.
I've found potassium chlorate can oxidize bromide with dilute sulfuric or conc. hydrochloric acid, but it's very slow and not really that practical.
No matter how I isolate it I always dry it with 98% sulfuric acid, re-distill and ampule it.
-The manipulator
We are all here on earth to help others; what on earth the others are here for I don't know. -W. H. Auden
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Ramium
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http://orgchem.colorado.edu/Technique/Procedures/Distillatio...
would this distillation setup work for distilling the bromine???
if so where would I get all the parts (I live in new Zealand)
thanks
[Edited on 13-2-2015 by Ramium]
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Metacelsus
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The only thing I would be worried about is the rubber seal on the thermometer. If you can get a ground glass seal, that would be better. You could try
ordering from Laboy glass; I think they ship to New Zealand.
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diddi
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agree. get a GG thermo adapter.
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Ramium
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thanks
guys!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!
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Ramium
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I found this at laboy glass
http://www.laboyglass.com/chemistry-distilling-set-24-40.htm...
is it suitable???
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Texium
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Yep, I'm aware of that, but it worked fine for me, and I was simply saying that although it's not ideal, if
that's all that he had access too, he could do it. Plus, chlorine produced should react further with the bromide to liberate more bromine.
Also, I apologize about the sulfuric acid blunder, I did not really think about that before I posted it.
[Edited on 2-14-2015 by zts16]
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blogfast25
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| Quote: Originally posted by zts16 | Plus, chlorine produced should react further with the bromide to liberate more bromine.
Also, I apologize about the sulfuric acid blunder, I did not really think about that before I posted it.
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The time I made that bit of Br2, I actually used Cl2 gas. But Cl and Br form inter-halogens like BrCl, another reason not to use HCl or Cl2.
[Edited on 14-2-2015 by blogfast25]
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Ramium
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| Quote: Originally posted by zts16 | Yep, I'm aware of that, but it worked fine for me, and I was simply saying that although it's not ideal, if
that's all that he had access too, he could do it. Plus, chlorine produced should react further with the bromide to liberate more bromine.
Also, I apologize about the sulfuric acid blunder, I did not really think about that before I posted it.
[Edited on 2-14-2015 by zts16] |
why cant I just use KMNO4 without any other oxidisers???
[Edited on 14-2-2015 by Ramium]
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blogfast25
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Nobody said you can't. You do need some acid too.
[Edited on 14-2-2015 by blogfast25]
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Ramium
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how about sodium bisulphate???
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blogfast25
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That would work, but you'll need 8 mol of it per mol of KMnO4.
Please edit your post upstairs, the one with all the !!!!!, it's buggering up the view of all posts on this page!
KMnO4 + 8 H+ + 5 e ==== > Mn2+ + K+ + 4 H2O
or:
KMnO4 + 8 NaHSO4 + 5 e ==== > MnSO4 + 1/2 K2SO4 + 4 H2O + 4 Na2SO4 + 5/2 SO4<sup>2-</sup>
And to complete it:
5 NaBr === > 5/2 Br2 + 5 Na+ + 5 e
[Edited on 14-2-2015 by blogfast25]
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Ramium
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| Quote: Originally posted by blogfast25 |
That would work, but you'll need 8 mol of it per mol of KMnO4.
Please edit your post upstairs, the one with all the !!!!!, it's buggering up the view of all posts on this page!
KMnO4 + 8 H+ + 5 e ==== > Mn2+ + K+ + 4 H2O
or:
KMnO4 + 8 NaHSO4 + 5 e ==== > MnSO4 + 1/2 K2SO4 + 4 H2O + 4 Na2SO4 + 5/2 SO4<sup>2-</sup>
And to complete it:
5 NaBr === > 5/2 Br2 + 5 Na+ + 5 e
[Edited on 14-2-2015 by blogfast25] |
sorry about the !!! Post i was very exited it wont let me edit it i
posted it on another computer .So could you tell me how much Potassium bromide sodium bisulphate and potassium permanagnate in grams???
[Edited on 15-2-2015 by Ramium]
[Edited on 15-2-2015 by Ramium]
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gdflp
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It depends on how much you want to synthesize. Blogfast gave you all of the information you need, you need a molar ratio of 1:5:8
KMnO4:KBr:NaHSO4 respectively.
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blogfast25
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| Quote: Originally posted by gdflp | | It depends on how much you want to synthesize. Blogfast gave you all of the information you need, you need a molar ratio of 1:5:8
KMnO4:KBr:NaHSO4 respectively. |
Ramium isn't well versed in moles. He needs to look that up and acquaint himself with it. Age, young or old, is no excuse here.
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Ramium
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lets say I want to make 20 ml of bromine
how many grams of potassium bromide potassium permanganate and sodium bisulphate would I need for that??????
[Edited on 15-2-2015 by Ramium]
[Edited on 15-2-2015 by Ramium]
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Magpie
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We get nervous when someone who doesn't know how to use moles asks how to make a very hazardous chemical.
Learn some chemistry first. You will also have more fun that way.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Ramium
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| Quote: Originally posted by Magpie | We get nervous when someone who doesn't know how to use moles asks how to make a very hazardous chemical.
Learn some chemistry first. You will also have more fun that way. |
I researched moles and work this.
If i started with 1 mole of KMNO4 i would need
KMNO4 =158.03 g
KBr = 5*119.00g = 595g
NaHSO4 = 8*120.06g = 960.48g
That would be too much, so 8 could divide by 10
So
KMnO4 = 15.80g
KBr = 59.5g
NaHSO4 = 96.05g
How much bromine would that make?
[Edited on 15-2-2015 by Ramium]
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Texium
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You need to know how to convert between moles and grams because that's the only way you can interpret chemical equations properly and find out how
many grams you need. If you hope to someday design your own procedures rather than following step-by-step instructions, it's the first basic skill
that you'll need.
Sure, we could spend a few minutes to do the calculations for you, but we call that "spoonfeeding" here, and that's not what we do, because you don't
learn anything, and will just keep asking these simple questions. Instead, how about if you go and find out how to do it yourself? I'll even get you
started: try googling "converting between moles and grams"
Once you've got that down, go check out oxidation-reduction and half-reactions, and that will help you with interpreting blogfast's equations.
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