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    (Original post by Supergirlxxxxxx)
    Got full marks


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    oooo check you out! xx
    well done!
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    Well it's chem, not hard for me! Obviously some people find it hard but I genuinely think it's the easiest but good luck for tomorrow


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    My teacher seems to think there will be a large question on hess's law, anyone agree?
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    (Original post by lastminutelarry6)
    My teacher seems to think there will be a large question on hess's law, anyone agree?
    yeah! defo!
    no hess law last year
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    in the test bank on slide 10 the enthalpy change question why does the mass of the calorimeter 120g suddenly become 1.2 when doing calculations? help pls
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    (Original post by buckeybarnes)
    in the test bank on slide 10 the enthalpy change question why does the mass of the calorimeter 120g suddenly become 1.2 when doing calculations? help pls
    You aren't using the mass of the calorimeter, I believe that's only there to trip people up. 1.2g is the mass of fuel burned 43.56-42.36 = 1.2g used. Which you then convert to moles etc.
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    Hess Law will blow up this year too.
    So will the three hydrocarbon processes

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    Whats the difference between covalent and dative covalent?
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    Dative covalent is where an atom donates both of its electrons in a covalent bond


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    (Original post by barbiex)
    Whats the difference between covalent and dative covalent?
    NH4 is an example they like to use a lot
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    Anyone have a copy of the spec with the model answers included? I found one for F335 on here the other day but none for F331 yet
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    (Original post by Petulia)
    Anyone have a copy of the spec with the model answers included? I found one for F335 on here the other day but none for F331 yet
    Could you link the F335 one?
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    Can anyone explain Q 2d in the june 2014 paper
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    (Original post by Bruhh)
    You aren't using the mass of the calorimeter, I believe that's only there to trip people up. 1.2g is the mass of fuel burned 43.56-42.36 = 1.2g used. Which you then convert to moles etc.
    ah ok ty
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    (Original post by Harrycarter96)
    Could you link the F335 one?
    http://www.thestudentroom.co.uk/show....php?t=1307590

    F335 spec with model answers attached, I think she posted F334 a bit later as well.
    There's also OCR Biology specs there.
    Let me know if you find anything like this for F331!
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    If anyone has that spec please let us know or any notes.

    Thanks

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    can anyone give me a quick overview on calculating empirical formulae?
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    (Original post by buckeybarnes)
    can anyone give me a quick overview on calculating empirical formulae?
    Divide the percentage of each atom which is basically its mass in the compound by its atmoic mass to find the moles of it

    Do this for all the atoms in the compound .Now find the ratio of the atoms by dividing each of the atoms moles by the moles of the atom that he smallest mole

    This would give you a ratio e.g. 2:2:1. Then just put the ratio of each atom in the formula e.g. C2H2O
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    (Original post by buckeybarnes)
    can anyone give me a quick overview on calculating empirical formulae?
    Calculate the moles by doing mass divided by Mr
    Divide each of the moles by the smallest moles number
    Put them into a ratio
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    Somebody quickly go over Hess' law calculations for me please?
 
 
 
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