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    tfw you're going through the test bank and you're on slide 10 of 189. gonna be a long night
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    (Original post by The fish inspect)
    Coordination number is the number of dative covalent bonds
    Yeah i know that just wasnt aware EDTA4- formed 6 bonds with a central atom. If so is it always 6?
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    hydrolysis of amides with moderately conc naoh reflux you get a sodium salt and amine, right?
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    (Original post by misteltain)
    For one of the questions they asked to draw an electrochemical cell for copper and iron. The copper electrode was copper metal but the iron was platinum. Why is that?
    you use platinum when it involves molecules and ions or just ions. fe3+ and fe2_ both ions so use platinum electrode
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    Guys, get a good night sleep, wake up early in the morning tomorrow, go for a walk or quick gym/ come back, go over the notes for the last time, and then smash this exam
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    (Original post by MathsAddict)
    Yeah i know that just wasnt aware EDTA4- formed 6 bonds with a central atom. If so is it always 6?
    They only mention edta4- so it will be six coordinate bonds. They shouldn't be cruel and use a different charge. You'know the bas***ds at OCR
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    (Original post by MrPolish)
    Guys, get a good night sleep, wake up early in the morning tomorrow, go for a walk or quick gym/ come back, go over the notes for the last time, and then smash this exam
    I've always been told not to revise on the day of the exam,
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    (Original post by misteltain)
    There was a past paper question asking you to name an ether though so I wouldn't risk it. It's straightforward anyway.
    How do you name ethers ?


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    (Original post by pinkgorilla)
    How do you name ethers ?


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    If you google it you should get plenty of resources, I'm not that great at explaining organic nomenclature. But basically it's -oxy -ane, the shorter part of the carbon chain is the oxy e.g. methoxy and the longer part is the -ane e.g. ethane = methoxy ethane.
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    (Original post by The fish inspect)
    I've always been told not to revise on the day of the exam,
    same it stressed u out more, but skimming over notes for recap should be fine.Its the learning thats the issue
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    Hey does anyone know what's going on in Jun 2013 4aiii) (with the 2 step hydrolysis question about the rate determining step). http://www.ocr.org.uk/Images/175448-...-materials.pdf

    I looked at the solution in the mark scheme but it doesn't seem to explain very convincingly. If you look at http://www.chemguide.co.uk/physical/...ordermech.html,
    near the bottom of the page, there's a section describing how to deal with a multi-step reaction with equilbrium.

    But if you look at the exam question from F334, surely you'd have Kc = [H3O+][OH-] / [H2O]^2, and since [OH-] = [H3O+], [OH-]^2 = Kc[H2O]^2, so taking square roots [OH-] is proportional to [H2O] and so plugging that back into the slow step, surely overall it should be first order with respect to [H2O]?
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    so its 4:00am and im still not ready
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    (Original post by qwepoizxcmnb)
    Hey does anyone know what's going on in Jun 2013 4aiii) (with the 2 step hydrolysis question about the rate determining step). http://www.ocr.org.uk/Images/175448-...-materials.pdf

    I looked at the solution in the mark scheme but it doesn't seem to explain very convincingly. If you look at http://www.chemguide.co.uk/physical/...ordermech.html,
    near the bottom of the page, there's a section describing how to deal with a multi-step reaction with equilbrium.

    But if you look at the exam question from F334, surely you'd have Kc = [H3O+][OH-] / [H2O]^2, and since [OH-] = [H3O+], [OH-]^2 = Kc[H2O]^2, so taking square roots [OH-] is proportional to [H2O] and so plugging that back into the slow step, surely overall it should be first order with respect to [H2O]?
    It's because the rate determining step is directly determined by the products in the first equation, and two H2O molecules are needed to produce 1 OH- so H20 has double the effect on the rate determining step than CH3Cl, if that makes sense?
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    Can someone please explain how cis- trans isomerism occurs when there are two chiral carbons
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    (Original post by misteltain)
    For one of the questions they asked to draw an electrochemical cell for copper and iron. The copper electrode was copper metal but the iron was platinum. Why is that?
    It's because for the redox reaction for iron is between fe2+ and fe3+ therefore neither can form a electrode because they are ions. So you use a platinum electrode in a similar mechanism to the standard hydrogen cell
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    (Original post by MathsAddict)
    Its like trying to put your left hand and right hand which are mirror images of each other. Put them on top of each other they can't fit in to each other they are non-superimposable.
    but how does that make glycine superimposable :/
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    (Original post by tealover96)
    Can someone please explain how cis- trans isomerism occurs when there are two chiral carbons
    Which question is this referring to?
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    (Original post by BrokenS0ulz)
    Which question is this referring to?
    June 13 3d
    I'm not sure exactly when this occurs so the way I asked the question is likely wrong
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    (Original post by tealover96)
    June 13 3d
    I'm not sure exactly when this occurs so the way I asked the question is likely wrong
    Yeah normally, chiral molecules wouldn't show cis-trans isomerism because they are usually just alkanes, so can freely rotate around the C-C bond. The reason this shows cis-trans isomerism is because the ring structure stops the C-C from rotating. Imagine if you created a ring of 6 carbons with a modelling kit, you wouldn't be able to twist the carbons around without snapping the bonds.
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    (Original post by BrokenS0ulz)
    Yeah normally, chiral molecules wouldn't show cis-trans isomerism because they are usually just alkanes, so can freely rotate around the C-C bond. The reason this shows cis-trans isomerism is because the ring structure stops the C-C from rotating. Imagine if you created a ring of 6 carbons with a modelling kit, you wouldn't be able to twist the carbons around without snapping the bonds.
    Ahh right thanks!
    We were taught that cis trans isomerism only ever occurs at c=c...clearly not
 
 
 
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