The Home Scientist 020 - Isolating Bromine

[UC235]

2Br- --> Br2 + 2e-

H2O2 + 2H+ + 2e- --> 2H2O

Without a stoichiometric amount of acid, the reaction will not go to completion. It does not appear that you used enough HCl from the video. Others have had near theoretical yields of bromine when using a slight excess of acid.

[HazMatLabz]

Just wondering, is the aerial concentration of bromine from this reaction dangerous; chronically or acutely?

[MegaChemboy]

get your bromide salt, add just enough hydrogen peroxide to dissolve it, then add concentrated 98% sulphuric acid dropwise, in an ice bath, add ( by volume) aproximatly half the amount of bromide you used in sodium thiosulphate to clean to solution, then pipete out the bromine on the bottem of the vessel, all appuratus must be glass, the experement is life-threatining, attempt at your own risk, store the bromine in a flame-sealed glass vessel, a pipete for small amounts, a test-tube for large.

[nickbhalo]

I think the problem is too much water. You dissolved the sodium bromide in water, added hydrochloric acid, which is typically 64% water, and drugstore hydrogen peroxide which is 97% water. Also, bromine is a liquid, not like solid iodine, so the bromine was dissolved in the water.

[Digadogup]

@TheHomeScientist

is there any way to concentrate H2O2?

to increase reaction speed

[njx8]

Wow pro

[AlChemicalLife]

can i use 30% hydrogen peroxide cause that seem like it would work better cause it is stronger then 3% and should give better bromine

[ubuntupokemoninc]

How do i make hydrocloric acid?

[alessio3521]

you could write the formulas of the corresponding reactions?

[madjimms]

Can you bear my children?

[TheHomeScientist]

@madjimms

Sorry. I'm a guy.

[darrinr769]

@TheHomeScientist YOUR A BOSS BRO!

[FortNikitaBullion]

When I was a kid, I used to think red food coloring was bromine. They look so similar!

[98JMA]

Aren't the bromide ions REDUCED to elemental bromine rather than oxidized??

'OIL RIG' - Oxidation is Loss, Reduction is Gain.

[FortNikitaBullion]

@98JMA To go from bromide ion to elemental bromine, you would have to lose an electron. It's oxidation.

[98JMA]

@FortNikitaBullion

Oh, yes - I was accidentally considering bromide a cation rather than an anion. Thanks for pointing that out!!

[megamarko94]

Oh ok I look forward to it.

I am gonna start making videos soon I just need to buy hd camera ...

[megamarko94]

Why did you stop making videos

[TheHomeScientist]

@megamarko94

I haven't. I've simply put them on hold while I work on several projects that are high priority right now.

[blueduderanch]

@TheHomeScientist what kind of things are you working on?

[TomSteel101]

The problem with using hydrogen peroxide is that it is also a reducing agent.

H2O2 + HOBr --> O2 + H+ + Br- + H2O

It would be better to use sodium hypochlorite or chlorine gas. Chlorine gas will only add chloride ions, which will be added by the hydrochloric acid anyway. If you use sodium hypochlorite, you should add it before adding the hydrochloric acid to avoid creating chlorine gas.

[FortNikitaBullion]

Can you do this for chlorine as well, or is it just bromine and iodine?

[TheHomeScientist]

@FortNikitaBullion

Just bromine and iodine. There are cheaper, better ways to produce chlorine gas.

[spotlightman1234]

@TheHomeScientist you would have to use Hydrofluoric acid also right?

[acomaco2]

is this nurdrage?

[TheChemlife]

how do you remove the bromine from the solution onces it has reacted with the oxidizer? Because it's a liquid unless you freeze it you can't use filtration and heating it will loose a lot of product

[olympicfan2]

the most best way to make bromine is to bubble chlorine gas into a sodium or potassium bromide solution and than destill the bromine water^^ you would get almost 100% sodium or potassium bromide reacted.

[mewrox99]

You could make bromine electrochemical and distill it, that would be an awesome but dangerous experiment

[olympicfan2]

oh pleas dont use bleach. the best way is to destill that stuff and use manganese dioxide or some 30% hydrogen peroxide. the best acid for this is sulfuric acid.

[Kryptic890]

I did this in my backyard (several times) with quick, near instant results! Used 3% H2O2 with KBr dissolved in water and added to a long necked flask with a side arm. Put rooto H2SO4 in an addition funnel (~stoichiometric amount), put the funnel through a cork, attached some tubing to the side arm and led to a flask put in an ice bath. On addition the H2SO4 mixing with water produces strong heat which I think helps expel the bromine from the water, through the tube to condense in the receiver. 

[Kryptic890]

... naturally the tubing was attacked but I was able to isolate a few mL of liquid bromine in the flask. Enough to vigorously react with Al foil and zinc powder. Mixed with thiosulfate to convert back to bromide for cleanup.

[FortNikitaBullion]

I think the problem was the peroxide. The bromine probably reacts with it to form bromates, which are also colorless. Have you tried the reaction with bleach instead?

[TheHomeScientist]

@FortNikitaBullion

No. I used hydrogen peroxide because I didn't want to introduce impurities unnecessarily. I may try bleach next time.

[vmelkon]

What about electrolysis of a NaBr solution. It should form Br droplets at the anode.

[TheHomeScientist]

@vmelkon

Yes, that'll work. I wanted to use a chemical process rather than electrolysis, but if I actually need some bromine water I'll run current through a concentrated NaBr or KBr solution.

[vmelkon]

@TheHomeScientist Yes, that's one thing to worry about : a water bromine solution. Probably the best method is with high conc HCl or H2SO4 and NaBr.

[mikeysgame]

if we were able to isolate elemental bromine through this method would it be ok to store a small sample 0.5ml or less in somthing like a 1 dram glass vial with a plastic screw top My concern here is that the plastic screw cap would not be able to resist attack by the bromine. I have caps with and without polyseal and i dont know if either will work. Any ideas?

[TheHomeScientist]

@mikeysgame

You'd probably be okay with the polyseal vial, but it'd be better to use an ampule that you can melt closed.

Be extraordinarily careful if you deal with liquid bromine. It is truly nasty stuff. Work with a goggles and a face shield and under a hood, and double-glove.

[PyroErlend]

@mikeysgame I'd recommend you seal that vial with some teflon plumbing tape. It's dirt cheap at the hardware store and will probably keep that bromine in for some time.

[olympicfan2]

your best video ever!!! can´t get enough.:-)

[PEA1222]

Distill the bromine water.

[mrhomescientist]

Nice video! I imagine this reaction would work with lithium bromide as well? Any ideas why yours didn't turn out as you expected? I'm trying to find a good way to get elemental bromine for my element collection.

[TheHomeScientist]

@mrhomescientist

Lithium bromide should work fine, but be extremely careful handling the bromine you produce. I think my sodium bromide was the problem. Olympicfan2 repeated the experiment with KBr, 30% H2O2, and H2SO4 and got a good yield.

[CaptainDonou]

Bury college, Manchester, England. Its not to bad, we never use any chemicals that are potently harmful over one mole concentration in fact we rarely use anything of 0.900 mole Safety goggles are a must and lab-coats. We have safety inspectors and they clear us. We are also cleared for Radioactivity experiments this is the only time we wear gloves when handling a radioactive source but this is almost always done by the tutor.

[CaptainDonou]

my college forbids us to ware gloves for the danger that if they are exposed to heat they could melt to our skin. Is this really a danger i the lab? When not around Bunsen burners i mean

[TheHomeScientist]

@CaptainDonou

Wow. Which college is this? It sounds like they have a pretty strange set of priorities. I've never heard of anyone being injured by a glove fire, but I've sure heard of a lot of people who were injured or killed because they weren't wearing gloves or wore the wrong type.

[Neilidity]

I know it should make no practical difference really, but in your preparation I would not use HCl, preferring H2SO4 as then there can be no funny halogen interactions (although it should not matter anyway, as any Cl2 produced should in turn oxidise your bromide to bromine).

You mention in one of your replies that next time you would use electrolysis - what electrode would you favour for the production of bromine?

[TheHomeScientist]

@Neilidity

You're absolutely right. I used HCl because it should work fine and I get 31.45% HCl at the local big box DIY store for about $7 a gallon.

As far as electrodes, I'd probably use platinum on general principles, but I suspect carbon would also work.

[Neilidity]

Thanks for the info - I have platinum wire, but even this is not cheap :(

[adriiPortillo]

Humm... Too bad it didnt work. I would like to try to oxidize halogens, like bromine to hypobromite.

[TheCaptainLulz]

i tried bubbling chlorine gas through a 35% NaBr sollution and it formed nearly instantaneously. oh and for the guy talking about distilling it, it works but I've yet to find a container that will hold it for any prolonged period of time, it seems to find its way out of just about anything.

[chasson321]

Would you consider showing how to make sodium chlorite from sodium chloride?

[TheHomeScientist]

Sorry, but no. Sodium chlorite is cheap and readily available. Synthesizing it is dangerous, involving extremely toxic and explosive chlorine dioxide.

[adriiPortillo]

How about auto-oxidation of hypoclorite to chlorite? no chlorine dioxide needed.....

[TheHomeScientist]

I've never done that. Details?

[adriiPortillo]

Well.... When heated, sodium (or caclium) hypcolorite decomposes oxidizing another hpyoclorite molecule, to form chlorite. Further decomposition makes it up to chlorate and even perchlorate. This can be done on a water solution safely if admixed with a stronger oxidizer than chlorate, like permanganate or persulphate. peroxide doesnt work. I tried it.

[recremkram]

why not distill it?

[TheHomeScientist]

Bromine water is nasty enough. You really, really don't want to mess with liquid bromine. About the only use I have for bromine in my lab is doing quick tests of organics for unsaturation. For that, bromine water works quite well, and is much, much less hazardous to store and use than liquid bromine.

[mario8401]

Yes you have right Sir , in chemistry on thing is on paper and other thing in practice , nice video ! 5/5

[waskaman94]

would i be able too use this same method too extract the elemental boron from sobium boride or manganese from sodium manganate

[imgeek1337]

to make bromine, you can distill a mixture of manganese dioxide, sulfuric acid, and sodium bromide. Nurdrage has a video about how to get manganese dioxide from batteries

[quantumdude]

Solution is transfered to 500 ml flask and 17.5g of potassium bromate is added by small portions with stirring. Stirring is continued until large drop of liquid bromine is formed in the bottom. Bromine is separated on separating funnel and dried with concentrated H2SO4. Yield is almost quantative, but some ammount of bromine remains dissolved in water (it is not large and depends from temperature).

[TheHomeScientist]

Alas, potassium bromate is an expensive chemical and not one that's readily available from other than specialty lab suppliers.

[quantumdude]

@TheHomeScientist I beg to differ, reagent grade potassium bromate can easily be synthesize by electrolysis of a solution of potassium bromide (KBr)and potassium dichromate (K2Cr2O7). A platinum wire or graphite rod can be used as anode.

[HazMatLabz]

@quantumdude it is expensive and why not use chlorate or something. sure, you can order it from like strem chemicals but that is for companies only.

[quantumdude]

Procedure is straight forward: 63g KBr is dissolved in 300 ml of water, 18 ml of 95% H2SO4 is added with stirring (car battery acid can be used to disslolve KBr, taken in such ammount that resulting H2SO4 concentration is about 10%).

[quantumdude]

A far superior method is to use potassium bromate as an oxidizer according to:

5KBr + 3H2SO4(aq.) + KBrO3 => 3Br2 + 3K2SO4 + 3H2O

[decibelchild]

exothermic?

[zbret]

I tried the same thing at one point, and i too wound up with a brown liquid. I figured, no problem, just get it up around the Br boiling point (under 60C). I had the darn thing near 100 and it was just barely vaporizing. My plan was to send the gas into a tube immersed in dry ice/acetone (-79C) to get Br crystals. The result was just a fuming mess with no yield. I concluded the Br water doesn't like to separate as much as you would think it would. I'd still love to make some Br sometime.

[panzuman]

why not use the dilute H2O2 to disolve the bromine salt? and possibly boil down the peroxide to concentrate it? (p.s. boiling does actually work ive done it many atime)

[TheHomeScientist]

Actually, I wanted the excess water. I thought I'd end up with about 4 grams of bromine. The room-temperature solubility of bromine is about 3.5 g/dL, so I figured the 100 mL of water (~25 mL to dissolve the NaBr and about 75 mL from the H2O2) would dissolve about 3.5 grams, leaving me with maybe half a gram (a few drops) of liquid bromine in the flask. Obviously, it didn't work out that way.

[mikeysgame]

do you thiink that reagent grade potassium bromide would work as well? also, will you be doing another video on this becuase i would love to know the best way to distill it.

[TheHomeScientist]

KBr should work fine.

I'm not planning to revisit this topic. Several of the comments have details about getting proper yields. The only time I'd produced bromine before was by electrolysis, and that's what I do again if I really needed some.

You really, really don't want to mess with distilling elemental bromine unless you just have to. It's extremely nasty stuff.

[Juiceton5000]

This reminds me of a lab my AP Chemistry class did. We were doing a synthesis of Aspirin, and something went very wrong for another one of the lab groups, and they ended up with only 3% yield. I know every chemist has had his or her fair share of error.

[TheHomeScientist]

Better than the time in first-year organic that I got a 104% yield on a synthesis. Everything else was right: sharp melting point, IR, NMR, etc. But I apparently violated the conservation of matter rule, which would have gotten me a zero grade. Fortunately, one of the other guys confessed it had been a practical joke. All of them took a tiny bit of their product and added it to mine. Our professor was not amused with them.

[Juiceton5000]

Wow, good thing they confessed.

[tarsman013]

I love when even a successful chemist like yourself is not afraid to talk about their mistakes (and then pus safety). Great Job!!

[TheHomeScientist]

Any chemist soon learns that things sometimes don't go as expected. When I first shot this video, I was originally going to troubleshoot the problem and then reshoot the video to show things the way they were supposed to work. Then I decided that it'd actually be better to show the failure, because inexperienced home scientists often think a failure is their fault. Instead of just repeating the experiment and trying to figure out what went wrong, they give up.

[TheHomeScientist]

As my wife commented, chemistry really is a lot like cooking (which, after all, is just applied chemistry). A recipe that's worked every time for years can suddenly fail for no apparent reason. It may be minor differences in the materials used or in the reaction conditions, and exactly the same problems occur in chemistry labs.

[yahoorif]

you said you can oxidise the sodium bromide solution with laundry bleach. you mean sodium hypochlorite?

[TheHomeScientist]

Yes. Chlorine bleach (sodium hypochlorite) or bleaching powder (calcium hypochlorite) should both work. Of course, the sodium hypochlorite worked only marginally for me. I'm still thinking my crude sodium bromide was perhaps much less than 100% sodium bromide. I'd test it for purity, but I only had a few grams that someone gave me and I used all of it.

[yahoorif]

Thanks!

[meemoeuk]

Did you figure what went wrong?

I think there was too much water.

[TheHomeScientist]

I don't think the problem was excess water. If I had time, I'd reproduce the experiment using lab grade or better sodium bromide to see if the problem was with the starting material. It may be that instead of the relatively high percentage of bromide I assumed, this stuff was actually only a small percentage of sodium bromide.

[pyropakman]

Failure is always an option in science!

You could use electrolysis to do this with better yield, but that raises a question: I have titanium cathodes (my dad is an engineer), but where would you recommend I find cheap platinum or platinum-plated anodes? Graphite rods from a lantern battery work alright, but the particle contamination can be a real pain.

Thanks!

[TheHomeScientist]

Platinum is so expensive that cheap platinum electrodes is an oxymoron, but you can get platinum-plated electrodes at reasonable prices from most lab suppliers. I prefer the kind that are a grid or a mesh, because it increases the surface area of the electrode.

[pyropakman]

Thanks! Do you have any recommendations? Suppliers that have reasonable prices and good value?

Thanks again!

[hkparker]

I have isolated bromine before using the reaction Ca(ClO)2 + 4NaBr + 2HCl --> 2Br2(l) + 4NaCl + Ca(OH)2. The reaction occurred rapidly, and the Bromine produced was in a very concentrated solution that i distilled to yield pure bromine. I was working outside as the fumes were very nasty, I will try to shoot a video of the reaction sometime.

[BrotherBloat]

top notch stuff, as always! thanks :]

[HazMatLabz]

So since this is bromine water, is this acidic at all?

[isaisai9192]

Is it stable ?

[hkparker]

@isaisai9192 the bromine is quite volatile and slowly leaves the soln.

[twycross3]

Great video! Thanks for the info. I found it personally helpful.

[sciencoking]

i did this with potassium bromide and potassium permanganate as the oxidizer. The reaction went almost too fast for my taste (it became QUITE warm and lots of bromine evaporated... it was really nasty o0)

[antiswattt3]

sciencoking, gotta dilute the KMnO4 then :P just bought some today.. sure the best for FP ^^

[Chaoschemiker]

How about solve the bromine out of solution using benzene and isolating the bromine by destillation?

Or maybe directly use the benzeneous bromine-solution for brominating the benzene by adding a lewis-acid?

[tjiddles25]

cool reaction

just what i needed for my element collection. just buying is no fun at al.

and i think we have some sodiumbromide in our lab.

keep m coming!!

is it a good idea to use lab-grade 30% H2O2 or will that give unwanted or unsafe results?

[TheHomeScientist]

I've never done it with 30% H202, but it should work fine.

[antiswattt3]

tjiddles25, im sure higher concentration is just better (:

[farhmoha]

Cool