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    F2 is a pale yellow gas, Cl2 is a green gas, Br2 is a red-brown gas and red-brown liquid (standard state), I2 is a purple gas and dark-grey solid (standard state).

    What are the colours of these in aqueous solution? Are they all the same? And are they same in an organic solvent (hexane or cyclohexane) as well?
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    (Original post by Big-Daddy)
    F2 is a pale yellow gas, Cl2 is a green gas, Br2 is a red-brown gas and red-brown liquid (standard state), I2 is a purple gas and dark-grey solid (standard state).

    What are the colours of these in aqueous solution? Are they all the same? And are they same in an organic solvent (hexane or cyclohexane) as well?
    you cannot have a solution of fluorine ...

    ... the other elements tend to display their atomic (gaseous) colours in non-polar solvents.

    In reality they react partially with water producing a mixture of halo(I) and hydrohalic acids. This allows iodine to give the brown/orange solution as the iodide ions from the HI interact with the iodine molecules making triiodide ions ...

    .. all fun stuff!
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    (Original post by charco)
    you cannot have a solution of fluorine ...

    ... the other elements tend to display their atomic (gaseous) colours in non-polar solvents.

    In reality they react partially with water producing a mixture of halo(I) and hydrohalic acids. This allows iodine to give the brown/orange solution as the iodide ions from the HI interact with the iodine molecules making triiodide ions ...

    .. all fun stuff!
    Haha I just love the memorization of solution colours :rolleyes:

    Yes I should have excluded F2 in my original post, it will form HF straight away in solution (ok, maybe some HOF etc., I don't know - my intuition is that it's mainly HF?). So Cl2 in solution will be green, Br2 red-brown, but I2 brown (the one difference from its standard gas phase appearance) - but then in organic solvent, Cl2 is green, Br2 is red-brown, but I2 now is purple because (since there's no I- with which to produce I3-) it's the same colour as in the gaseous phase. Why doesn't the trihalide effect occur with the other halogens?
 
 
 
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