Colour changes of Alkenes and Bromine Water

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Hi, we've been told for a test coming up we need to make sure we know the reactions of Alkenes with Bromine water, and what colour the solutions change to.

I have nothing in my booklets - can anyone give me a brief summary? Thanks!

Posted Sat 5th May, 2012 @ 16:58 by Becky

6 Answers

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Molecule (alkenes) with c=c Carbon carbon double bonds turn bromine water coulourless... other molecules show no change x

Answered Sat 5th May, 2012 @ 17:05 by Edward Pinches
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Thanks a lot! Is that all I need to know?

Answered Sat 5th May, 2012 @ 17:06 by Becky
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I'm doing C3 AQA, and yeah that's pretty much you need to know for Unsaturated Hydrocarbons. (C=C bonds)

But remember to do memorise the flame tests, and the NaOH reactions, as they do come up often! (From looking at past papers)

Good luck! (: 

Answered Sun 6th May, 2012 @ 08:36 by Nishat Ahmed
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i can never remember what colour calcium burns any tips on how to memorise this

Answered Sun 6th May, 2012 @ 16:15 by Nathan
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C=C bonds ( unsaturated these are alkenes ) --- Colourless

C-C bonds ( saturated these are alkanes ) --- Stays the same (orange)

Make sure for C=C bonds you write, it goes colourless or decolourises because if you say it turns clear you won't get the mark.

Answered Sun 6th May, 2012 @ 17:30 by :) PurpleJaguar (: - Team GR
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@ Nathan
Hi there! :) 
Well Calcium always burns Brick Red, most people get it mixed up with Lithium that burns Bright red..
Im not sure but try making up a mnemonic 

If you need any other help, feel free to ask me! (:

Answered Sun 6th May, 2012 @ 19:36 by Nishat Ahmed