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Edexcel Official Chemistry Paper1:Core Inorganic and Physical Chemistry - 27th of May watch

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    (Original post by nav5678)
    what did people get for the multiple choice where is asked what happens when ammonium gas and bromine react? i wrote it decolourises
    White smoke would form. It's the same as reacting HCl with NH3
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    (Original post by damian21kk)
    Why would there be a peak at 80 in mass spectrometry of Bromine? There are only two isotopes of bromine- 79 and 81 so why would there be peak at 80?
    This is what I wrote:

    In the mass spectrometer, the two isotopes of Br79 ans Br81 combine to form Br2 with a mass of 160, however, the peak at 80 is due to the the charge of the Br2 being 2+ (so the m/z is halved 160/2 = 80) which forms the peak there. However it is very low because there is a very small abundance of that isotope being detected.
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    I think you will get most of the marks - you just forgot to times by 10
    (Original post by middleagedpotato)
    lets hope brother t-t
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    Was it nothing to do with carbon 13?
    (Original post by Florent venhari)
    This is what I wrote:

    In the mass spectrometer, the two isotopes of Br79 ans Br81 combine to form Br2 with a mass of 160, however, the peak at 80 is due to the the charge of the Br2 being 2+ (so the m/z is halved 160/2 = 80) which forms the peak there. However it is very low because there is a very small abundance of that isotope being detected.
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    What did everyone get for the theoretical amount of gas produced i cant remember the exact question but it was to do with magnesium and HCl
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    For the first 6 mark question, I wrote stuff like:

    • magnesium ribbon is big, so a lot of gas would be produced so use a smaller ribbon ( that's probably wrong because it said chemicals/ equipment)
    • measuring cyclinder has a low resolution so volume might be hard to measure, so use a gas syringe
    • the cyclinder was literally on the bed of the water bath, so the gas produced couldn't take up the volume of the cyclinder because the HCl couldn't escape the cycline ( Lol made that up)

    For the second 6 marker, I wrote about:

    Ionisation energy doesn't really link, but it does link with atomic radius and shielding, which affects how readily oxidized the metal is when reacting with water. So, overall, the rate is affected by atomic radius and it's oxidation ability, but not due to ionisation energy because that only occurs in gases but one can't get a metal gas. Some **** question.
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    (Original post by Marvin16)
    What did everyone get for the theoretical amount of gas produced i cant remember the exact question but it was to do with magnesium and HCl
    I think I got like 40 cm3 for the PV=nRT
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    (Original post by Shk)
    Was it nothing to do with carbon 13?
    I don't think so, but it could be....
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    (Original post by Florent venhari)
    For the first 6 mark question, I wrote stuff like:

    • magnesium ribbon is big, so a lot of gas would be produced so use a smaller ribbon ( that's probably wrong because it said chemicals/ equipment)
    • measuring cyclinder has a low resolution so volume might be hard to measure, so use a gas syringe
    • the cyclinder was literally on the bed of the water bath, so the gas produced couldn't take up the volume of the cyclinder because the HCl couldn't escape the cycline ( Lol made that up)

    For the second 6 marker, I wrote about:

    Ionisation energy doesn't really link, but it does link with atomic radius and shielding, which affects how readily oxidized the metal is when reacting with water. So, overall, the rate is affected by atomic radius and it's oxidation ability, but not due to ionisation energy because that only occurs in gases but one can't get a metal gas. Some **** question.
    I wrote
    -Use emery or sand paper to remove MgO from contaminated/impure Mg
    -Volume locked measuring cylinder (clamped as said in the question) so the pressure will increase if H2 forms, H2 volume will be compressed. As a result a wokable alternative would be to use a gas syringe which has an alterable volume capacity.
    -250cm3 volume with 30-40 cm3 of gas so there is a high % uncertainity. Thus, to reduce the % error. Use a gas syringe(gas syringes have lower volume) to reduce % error.

    For the 6 marks question:
    I know that Be doesn't really react with water and the reaction vigour with water increases down the group for group2. So I said that the lower the Total IE, the faster the rate.
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    (Original post by aipomaniac)
    It was definitely helpful, we carried it out under strict examination questions so it will be a true reflection of what we will actually achieve. I am not sure if that's a good thing this late in the course haha!

    The questions were slightly different to the past paper and I found the practice paper more difficult then the specimen paper that is available online, so that was useful to get more used to the new style of questions.
    Could you please upload those papers if you can?
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    (Original post by Florent venhari)
    I think I got like 40 cm3 for the PV=nRT
    Same! Something like 40.3
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    Anyone have any ideas on grade boundaries for this year?
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    (Original post by Raffparente)
    Anyone have any ideas on grade boundaries for this year?
    I have a feeling that:

    A - 64
    B - 58
    C - 51
    D - 46
    E - 39
    U - < 38

    Hopefully they're lower!
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    How did yiu draw the dot and cross diagram?
    And wgat did you answer for Nitrates question? ( why is MgNO3 decompose more readily than some other nitrate)
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    (Original post by Florent venhari)
    I think I got like 40 cm3 for the PV=nRT
    Same here, 40.2 cm3 i think
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    [QUOTE=amiliar;65238635]How did yiu draw the dot and cross diagram?
    And wgat did you answer for Nitrates question? ( why is MgNO3 decompose more readily than some other nitrate)[/QUOTE

    The dot and cross diagram is lower down the page here.
    http://www.chemguide.co.uk/atoms/bonding/dative.html

    For the second part, it was basically about thermal stability and polarisability
    • group 1 cations are more stable than group 2 cations
    • Mg has a 2+ charge, where as K has a 1+ charge
    • Mg 2+ has a smaller atomic radius than K+, so there is a larger electron density in Mg2+
    • therefore Mg2+ polarises the carbonate anion more than K+ does
    • so Mg(CO3)2 readily decomposes more than KCO3 because it is less thermally stable
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    [QUOTE=Florent venhari;65239027]
    (Original post by amiliar)
    How did yiu draw the dot and cross diagram?
    And wgat did you answer for Nitrates question? ( why is MgNO3 decompose more readily than some other nitrate)[/QUOTE

    The dot and cross diagram is lower down the page here.
    http://www.chemguide.co.uk/atoms/bonding/dative.html

    For the second part, it was basically about thermal stability and polarisability
    • group 1 cations are more stable than group 2 cations
    • Mg has a 2+ charge, where as K has a 1+ charge
    • Mg 2+ has a smaller atomic radius than K+, so there is a larger electron density in Mg2+
    • therefore Mg2+ polarises the carbonate anion more than K+ does
    • so Mg(CO3)2 readily decomposes more than KCO3 because it is less thermally stable
    Sorry, there shouldn't be a carbonate ion there. It should be the nirate
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    I think I got most of it correct. Just a couple of niggling errors such as in that horrid titration question and that balacing which just was hard to do. Second 6 marker wasn't that nice either, although seems I mentioned the poitns others have
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    (Original post by SolomonP)
    I think I got most of it correct. Just a couple of niggling errors such as in that horrid titration question and that balacing which just was hard to do. Second 6 marker wasn't that nice either, although seems I mentioned the poitns others have
    The balancing was:

    S8 + 8AgF2 -> 4S2F2 + 8AgF
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    (Original post by Florent venhari)
    The balancing was:

    S8 + 8AgF2 -> 4S2F2 + 8AgF
    I see
 
 
 
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