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Edexcel Chemistry IGCSE 1C Unofficial Mark Scheme 19th May 2016 Watch

  • View Poll Results: How did you find this exam?
    Very easy
    13.97%
    Easy
    28.19%
    Okay
    43.87%
    Hard
    10.78%
    Very hard
    3.19%

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    (Original post by conradliebers)
    I agree but I think they'll make paper 2 harder considering this one wasn't.
    Definitely - I'm thinking electrolysis (with Faraday calculations), harder mole questions, the contact process and more industrial processes in general, ionic and covalent bonding, condensation polymerisation - and maybe some actually chemistry knowledge?!

    I wish the paper had been harder, but with more defined answers...
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    (Original post by conradliebers)
    I really want to add them in but do you know roughly which question they came in?

    I think this exam was a lot easier than previous ones - especially people in my school - so I think they could be raised, but an A* will be around 75-80 %.
    what do you think an A will be
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    (Original post by gameofno)
    what do you think an A will be
    120/180
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    UGHHH i put 2 bromines i think i got the empircal formula for Y wrong too
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    do you know what the two observations were for the q where it asked what observations can be made when the calcium reacts with water?
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    Question about mass of water is 0.9g of water in CuSO4.5H20
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    (Original post by gameofno)
    do you know what the two observations were for the q where it asked what observations can be made when the calcium reacts with water?
    fizzing (hydrogen is given off) & the solid disappears (it dissolves)
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    Empirical formula for Y cannot be CH2......
    Y was an alkene it had a double bond, its formula was C3H6. C3H6 was the empirical formula because, they can both be divide by 3 to give CH2 (methene), but methene cannot exist as an alkene MUST HAVE A DOUBLE BOND. CH2 has one carbon therefore it cannot have a double bond and cannot exist.
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    (Original post by gameofno)
    do you know what the two observations were for the q where it asked what observations can be made when the calcium reacts with water?
    Effervescence/Fizzing
    Cloudy solution (MAYBE)
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    (Original post by Pedaly7)
    Empirical formula for Y cannot be CH2......
    Y was an alkene it had a double bond, its formula was C3H6. C3H6 was the empirical formula because, they can both be divide by 3 to give CH2 (methene), but methene cannot exist as an alkene MUST HAVE A DOUBLE BOND. CH2 has one carbon therefore it cannot have a double bond and cannot exist.
    Im pretty sure it is CH2
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    (Original post by defenestrated)
    fizzing (hydrogen is given off) & the solid disappears (it dissolves)
    woops will i get marks if i said bubbles of hydrogen appeared? lol
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    (Original post by HKHASSAN)
    Im pretty sure it is CH2
    i thought it was C3H6
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    (Original post by HKHASSAN)
    Im pretty sure it is CH2
    methene cannot exist.....
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    (Original post by Pedaly7)
    Empirical formula for Y cannot be CH2......
    Y was an alkene it had a double bond, its formula was C3H6. C3H6 was the empirical formula because, they can both be divide by 3 to give CH2 (methene), but methene cannot exist as an alkene MUST HAVE A DOUBLE BOND. CH2 has one carbon therefore it cannot have a double bond and cannot exist.
    that's why it can't be the molecular formula
    empirical formula is just the simplest whole number ratio
    (i think)

    (Original post by gameofno)
    woops will i get marks if i said bubbles of hydrogen appeared? lol
    yeah you should
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    (Original post by Pedaly7)
    methene cannot exist.....
    It is CH2 because it asked for the empirical formula - simplest ratio of atoms - so C3H6 goes to CH2.
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    (Original post by gameofno)
    do you know what the two observations were for the q where it asked what observations can be made when the calcium reacts with water?
    Eventually disappears, moves, floats on surface.
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    (Original post by HKHASSAN)
    Question about mass of water is 0.9g of water in CuSO4.5H20
    Yeah what question no.?
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    (Original post by conradliebers)
    Tell me the questions which I'm missing out - I'll add them in.

    1.a)
    Condensation. (1)

    1.b)
    Energy: average ke of particles decreases.
    Arrangement: the intermolecular spaces decrease (as some intermolecular
    forces between particles start to form).
    Movement: particles in liquids slide over each other. (3)

    2.a)
    Filtration. (1)

    2.b)
    Arrow drawn into solvent inside beaker.
    Arrow drawn onto chromatography paper.
    Arrow drawn onto the line on the chromatography paper. (3)

    2.c)
    There are for 4 dyes present in the substance as the original substance
    dissolved into the solvent and 4 dyes were drawn up. (1)

    3.a)
    Hydrogen molecule bonding - two circles that cross over each other and at the
    point of intersection there is a cross and a dot. The circles both have letters H
    inside of them. (1)

    3.b)
    Element in the air - argon. (1)

    3.c)
    Compound present in unpolluted air - H2O (water) or CO2 (carbon dioxide). (1)

    3.d)
    Isotopes are atoms with specific number of neutrons independent to the number of protons that defines the element. (2)

    3.e)
    H1 - 1 proton, 0 neutrons, 1 electron.
    H2 - 1 proton, 1 neutron, 1 electron.
    H3 - 1 proton, 2 neutrons, 1 electron. (3)

    3.f)
    Atom with 3 protons - the diagram with 3 dots.
    Atom in period 3 - the diagram with 15 dots (phosphorous)
    Atom with 15 electrons - diagram with 15 dots (phosphorous)

    4.a)
    Simple filling in the temperatures - to 1 dp. (4)

    4.b)
    Max temperature produced by magnesium. (1)

    4.c)
    Ice used to cool down and condense the water vapour. (1)

    4.d)
    Products formed - magnesium chloride and hydrogen (gas). (2)

    4.e)
    Increasing volume of acid to 50cm3 - not so great a rise in temperature as increase in volume of acid means that more energy is required for the same rise in temperature. (2)
    4.a)
    Copper pile turns black because the oxygen in the air reacts with it in a combustion reaction to form Copper oxide (black solid). (2)

    4.b)
    The gas is cooled down before it is measured so that its volume can be recorded at rtp (as the original volume had been measured in these conditions). Heated gases = expansion of volume. (1)

    4.c)
    Why didn't the small heap of copper turn black - because all of the oxygen in the air had been used up in the previous reaction hence no combustion reaction to oxidise copper. (1)

    4.d)
    Percentage of oxygen - 16.6 (recurring) or 16.7%. (2)

    5.a)
    In order of reactivity - Q, R, S, P. (4)

    6.a)
    Graph - draw straight lines of best fit, both lines must intersect. (4)

    6.b)
    Volume used - 12.5 cm3. (1)

    6.c)
    33 degrees celcius. (1)

    11.a)
    Propane. (1)

    11.b)
    C4H10. (1)

    11.c)
    W, X, Y. (1)

    11.d)
    Empirical formula for Y - CH2. (1)

    11.d)
    A hydrocarbon with a double carbon = carbon covalent bond.
    A hydrocarbon is a organic compound made of hydrogen and carbon only. (3)

    11.e)
    Displayed formula should have only 1 Br atom in it. (1)

    11.f)
    Condition required - UV light. (1)

    16.a)
    Draw graph line - steeper and levels off first but at same level. (2)

    16.c)
    Increase in concentration = increase in particles per unit volume, hence increase in no. of collisions per unit time hence increase in no. of successful collisions per unit time, hence increase in rate of reaction. (3)
    Holy moly I've done so bad At least I'll never have to do chemistry again
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    For the equation for H2 +O2, the answer is water.
    However, would H202 (hydrogen peroxide) be correct
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    (Original post by Chloe010300)
    For the equation for H2 +O2, the answer is water.
    However, would H202 (hydrogen peroxide) be correct
    Do you know roughly which question?
 
 
 
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