Australia's Science Forum

Morning everyone!

Yr 12 chem is doing a prac this afternoon with cyclohexene, cyclohexane and bromine water, I am sure you know the one I am talking about... I feel a bit lucky as the lady before me had purchased some already made up bromine water, so I dont have the hussle of making that up. But I am however a bit conserned as how to dispose of the waste once they are finished with it. CSIS doesnt say, at least not what I can find, it does say that solutions of <0.1% can be washed down the sink, but what do you guys do with solutions stronger than that???

Sassi

Dilute it with bucket loads of water? I'm not sure... I don't remember how we get rid of it.

We're doing that same experiment this morning! I use a solution of sodium thiosulfate to decolourise the bromine water and then flush it down the sink.
If you look at Appendix E in CSIS you'll find Disposal of Waste Chemicals. Bromine water comes under "16 Oxidising Agents".

Carol

After mixing with organics it should go into Halongenated organic waste

Thank you all for your input! I was thinking halogenated too, told the teacher and she muttered something like 'that doesnt sound right to me...' so then I got unsure. Just goes to show you cant listen to the teachers, shouldn't have doubted myself, grrrr!

Sassi

Disposal number 23 for both Cyclohexane & Cyclohexanene, Hold ready for collection, Your could even try evaporation in your fume cupboard.

We did that same experiment this morning too

I make the bromine water up from ampoules of bromine then put it into dropper bottles.
The waste from the test tubes that are mixed with Cyclohexane and cyclohexene go into our organic waste bottle. I put the dropper bottles back into the chemical store cupboardand then when the time comes around next year the water is completely clear so I can dispose of it down the sink and then fill my labelled bottles with the fresh solution.

Wierd thing though, It was initially wanted for first lesson yesterday so I made it up on friday but by monday morning it had totally lost all its colour and was useless! I don't know why, maybe I had the magnetic stirrer going too fast and caused most to vapourise or what ever it does, or left it too long before I put itinto the bottles.

It meant I had to do it all again this morning, Gown, gloves, rebreathing mask, the whole PPE, much to the amusement of the Yr 12 chem class

Wendy

Wendy try storing in the fridge

I had made it with Distilled water from the fridge and the ampoule had also been in the fridge. Then into brown bottles and back into the fridge.

Todays worked a treat though.

Wendy

There's a real easy method under 'Bromine' in CSIS Appendix F: just add a few drops of H₂O₂ & H₂SO₄ to dilute KBr solution.
I dispose of products in Halogenated Organic Waste bottle, and leave test tubes in fume cupboard to evaporate off residue. Cyclohexene is particularly horrible stuff.

Great tip, Xenon.

I make ours up using KBr, bleaching powder & sulfuric acid, but I've just read Appendix F, and think I'll give that quick method a go this time.

Many thanks,