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    (Original post by Rstlss)
    What's the back up paper?




    Yea I'm pretty sure so
    its when the official paper is leaked there is a R paper instead which is harder
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    (Original post by Lilieeeeeee)
    My teacher said we weren't able to and we would have to resit the whole year again i hope thats not the case, I'm so unprepared for chemistry and I need at least a C!
    im not prepared either too many exam one after the other thats stupid
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    Can someone please explain the trends down and across for first ionisations energys and boiling points etc im seriously struggling, also could you explain which deviate from the trend and how mg and Al differ, thanks!


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    Any predictions


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    Hi,

    In OCR AS Chemistry, what do you do with recurring numbers?

    Like for e.g. 47.6(recurring). Would it stay as 47.6 or 47.7? I think my chemistry teacher said OCR ignore recurring decimals.
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    (Original post by chuckster111)
    Hi,

    In OCR AS Chemistry, what do you do with recurring numbers?

    Like for e.g. 47.6(recurring). Would it stay as 47.6 or 47.7? I think my chemistry teacher said OCR ignore recurring decimals.
    Write the recurring answer in your working and then round your answer to whatever decimal place the other figures in the question are given to


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    (Original post by Sexybadman)
    Can someone please explain the trends down and across for first ionisations energys and boiling points etc im seriously struggling, also could you explain which deviate from the trend and how mg and Al differ, thanks!


    Posted from TSR Mobile
    Go check chemguide
    Anything anyone will write is going to be on it so save everyone's time!
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    Kk, what past papers should I do. Any common questions that usually come up? Also, how to prepare for section B, or is that just by hammering the past papers and you get a feel for them? Cheeeers
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    (Original post by jshep000)
    Kk, what past papers should I do. Any common questions that usually come up? Also, how to prepare for section B, or is that just by hammering the past papers and you get a feel for them? Cheeeers
    Just do every past paper

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    How do you do this question? I did (17.1/342), then multiplied the answer by 6x10^23 and got the answer C?
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    (Original post by jshep000)
    How do you do this question? I did (17.1/342), then multiplied the answer by 6x10^23 and got the answer C?
    There are three sulphate ions per 'molecule' of aluminium sulphate, so multiply your answer by 3 to get D?
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    (Original post by Sexybadman)
    Can someone please explain the trends down and across for first ionisations energys and boiling points etc im seriously struggling, also could you explain which deviate from the trend and how mg and Al differ, thanks!


    Posted from TSR Mobile
    First ionisation energies increase as you go across the periodic table because
    Electrons added to the same she'll
    Increased nuclear charge

    First ionisation energies decrease down the groups because
    More e- so more shells
    Outer electrons further from nucleus so can easily be removed
    More shielding

    Boiling points increase as u go down the groups due to the increase in van der waals (also applies to carbon chains - longer the chain - more van der waals - high boiling point )

    Phosphorus and Sulphur deviate because sulfurs outer electrons repel eachother making it easier to remove an electron

    Magnesium to Aluminum deviate because Mg outer electrons is is 3s subs hell where as Al is in a higher subshell 3p

    Beryllium and Carbon deviate as beryllium outer shell electrons are in 2s subshell and carbons are in 2p subshell (a higher one)
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    Can someone explain the electrophillic addition of bromine water to cyclopentene? Thanks

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    (Original post by samwillettsxxx)
    First ionisation energies increase as you go across the periodic table because
    Electrons added to the same she'll
    Increased nuclear charge

    First ionisation energies decrease down the groups because
    More e- so more shells
    Outer electrons further from nucleus so can easily be removed
    More shielding

    Boiling points increase as u go down the groups due to the increase in van der waals (also applies to carbon chains - longer the chain - more van der waals - high boiling point )

    Phosphorus and Sulphur deviate because sulfurs outer electrons repel eachother making it easier to remove an electron

    Magnesium to Aluminum deviate because Mg outer electrons is is 3s subs hell where as Al is in a higher subshell 3p

    Beryllium and Carbon deviate as beryllium outer shell electrons are in 2s subshell and carbons are in 2p subshell (a higher one)
    Yoo thanks for taking the time to do this its helped me a lot ! Safe bro 😄


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    (Original post by purplefoot)
    When you're testing for halides, I know you would normally add nitric acid and then silver nitrate but what would be the reason for adding the silver nitrate first and then the nitric acid? Any help would be appreciated- just can't seem to think why you would do it that way!
    You have to add the Nitric Acid first as this removes any possible interfering ions. If you did this in reverse order a e.g. White precipitate may form but it might not be Silver Chloride like you expect it to be!



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    (Original post by Sexybadman)
    Yoo thanks for taking the time to do this its helped me a lot ! Safe bro 😄


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    It's ok it helps me remember it having to write it out! You're welcome
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    (Original post by TeaAndTextbooks)
    Can someone explain the electrophillic addition of bromine water to cyclopentene? Thanks

    Posted from TSR Mobile
    So the double bond repel the electrons in the Br-Br polarising it
    The Br-Br bond breaks and the Br closest to the double bond gives up its electrons to the other Br and sticks to the C atom
    The other C atom gets positively charged (carbocation)
    The Br- then bonds to the positive carbon
    It's just the same as you would do electrophilic addition with HBr
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    Has anyone get any useful links to videos for balancing equations please. Thatd be awfully helpful
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    IS anyone sitting the Edexcel AS chem unit 1 June 2015?
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    (Original post by ILOVEA-LEVELS)
    IS anyone sitting the Edexcel AS chem unit 1 June 2015?
    Yes I am
 
 
 
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