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Edexcel - Chemistry Unit 2 - 4 June 2013 Watch

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    (Original post by samsimmons)
    Can someone tell me the colours of Bromine gas, Bromine in aqueous solvent, and Bromine in hydrocarbon? Thanks.
    Chlorine - colourless in both water and hexane (polar solvent)
    Bromine - orange in water and orange in hexane (polar solvent).
    Iodine - brown in water and violet in hexane (polar solvent)

    Bromine as a gas is orangey/brown: https://www.google.com/search?site=&...mg.483-Psm4Ltk
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    (Original post by HarryMWilliams)
    Chlorine - colourless in both water and hexane (polar solvent)
    Bromine - orange in water and orange in hexane (polar solvent).
    Iodine - brown in water and violet in hexane (polar solvent)

    Bromine as a gas is orangey/brown: https://www.google.com/search?site=&...mg.483-Psm4Ltk
    Thank you! Textbooks say different things, it's so confusing!
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    Is it a good and a better idea to do section b and c first and then the damned MCQs.
    There will definitely be some difficult ones that one would leave for the end so why not do them at last. Also we could plan the time more effectively, doing section b & C in a hour and at most 70 mins...
    :rolleyes:

    What are your opinions? I tried it for UNIT 1 and I feel that I did well and better on the MCQs than otherwise
    .
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    (Original post by samsimmons)
    Thank you! Textbooks say different things, it's so confusing!
    No worries.

    (Original post by TheKingOfTSR)
    Is it a good and a better idea to do section b and c first and then the damned MCQs.
    There will definitely be some difficult ones that one would leave for the end so why not do them at last. Also we could plan the time more effectively, doing section b & C in a hour and at most 70 mins...
    :rolleyes:

    What are your opinions? I tried it for UNIT 1 and I feel that I did well and better on the MCQs than otherwise
    .
    I would get them out of the way, if you dont get an MCQ, leave it and come back to it. But make sure you do come back to it and not completely forget like someone I know did.

    Ideally, you would have 15 minutes after finishing the paper to go back through and read everything to make sure you've covered enough.
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    (Original post by TheKingOfTSR)
    Is it a good and a better idea to do section b and c first and then the damned MCQs.
    There will definitely be some difficult ones that one would leave for the end so why not do them at last. Also we could plan the time more effectively, doing section b & C in a hour and at most 70 mins...
    :rolleyes:

    What are your opinions? I tried it for UNIT 1 and I feel that I did well and better on the MCQs than otherwise
    .
    But the MCQs are the best bit! Haha.
    If it works for you, than you should do it!
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    Thanks posthumous and ramanan, very helpful


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    (Original post by rockstar101)
    Ok it is trigonal planar by the carbon atom forms 2 double bonds with two xygen atms and then the third oxygen provides its lone pair of electrons to form a dative bond thus the 2- value of co3 if im not wrong
    hmmm, I dn't think carbon can have that many bonds lol
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    (Original post by Baraf)
    hmmm, I dn't think carbon can have that many bonds lol
    Carbon forms 4 covalent bonds - in carbon dioxide, the carbon is double-bonded to each oxygen atom, therefore, the oxygen atoms have two lone pairs each left over.
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    (Original post by HarryMWilliams)
    Carbon forms 4 covalent bonds - in carbon dioxide, the carbon is double-bonded to each oxygen atom, therefore, the oxygen atoms have two lone pairs each left over.
    yes but can Carbon form two double bond with two oxygen and then on top of that a dative covalent bond with a third oxygen. ?
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    (Original post by Baraf)
    yes but can Carbon form two double bond with two oxygen and then on top of that a dative covalent bond with a third oxygen. ?
    I believe so, it's called carbontrioxide, although it's apparently very unstable.
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    (Original post by rockstar101)
    When it decomposes due to heat it produces co2 which makes the cake rise and soft. Lol. Dw
    Agh I thought of it but then I thought it was wrong eventually ran out of time leaving it blank how many marks was it ??? Thanks by the way :P
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    In ozone depletion reactions, like NO + O3 --> NO2 + O2, is 'NO' a free radical?
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    (Original post by SKK94)
    In ozone depletion reactions, like NO + O3 --> NO2 + O2, is 'NO' a free radical?
    Usually they accept it as a radical and not as a radical.
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    NO is a free radical. Sometimes in the exam they don't include the dot, just to confuse you.
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    (Original post by wbrian)
    Agh I thought of it but then I thought it was wrong eventually ran out of time leaving it blank how many marks was it ??? Thanks by the way :P
    aww lol it was one mark so no stress. just conc on unit 2 now
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    (Original post by posthumus)
    It was locked or something 4 days ago, but only for a couple of hours

    How'd you find unit 1 ?
    Oh right.

    Sorry for the late response, I've been exhausted.
    Last day at school last Friday and we had days of pure messing around. It was so fun all the pranks we played and just eating in the Chemistry labs and partying the same evening! Really took my mind off things but I need to get back to studying for Biology and German! Chemistry's on hold for about a week or two. (Although I know I'll wander back to it when I get bored)

    Unit 1: I just felt like they were trying to make us apply our knowledge of trends to unfamiliar elements so I did have to do a little bit more thinking on the isotope questions, and then the Hess Cycle I definitely messed up, as well as the Calorimetry and percentage error. Essentially, the mathematical bits. I know the more familiar organic chemistry was absolutely fine. It'd annoy me if I made silly mistakes on that, because those are the bits I absolutely knew.

    Multiple Choice was okay, but taxing on the mind to put in second electron affinity, but I put first electron affinity as exothermic in the end which seems to have been correct. I'm really terrible with Mean Bond Enthalpies, so I may well have lost 10 marks at minimum, more than that at maximum XD and I would really love high UMS, or as close to maximum as possible. If not, it's not the end of the world at all, it just means I have to be a boss at Unit 5 which isn't impossible, it's just a bit scary to put all your hope in the hardest paper :confused:

    How did you find it?
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    (Original post by samsimmons)
    Usually they accept it as a radical and not as a radical.

    (Original post by James A)
    NO is a free radical. Sometimes in the exam they don't include the dot, just to confuse you.
    Alright, thanks!
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    Hey guys,

    I was wondering if we could make a list of all the practicals we need to draw/ write about for unit 2, I should've done this for unit 1, as one of the questions I mucked up completely was the drawing the practical one -_- aha.... :/

    Thanks in advance!
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    (Original post by coolio41)
    Hey guys,

    I was wondering if we could make a list of all the practicals we need to draw/ write about for unit 2, I should've done this for unit 1, as one of the questions I mucked up completely was the drawing the practical one -_- aha.... :/

    Thanks in advance!
    That's a really good idea!
    The ones I can think of right off hand are... oxidation of alcohols/elimination/substitution...?
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    (Original post by rockstar101)
    aww lol it was one mark so no stress. just conc on unit 2 now
    yeahh dont want too screw that as well thankss
 
 
 
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