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2016 IGCSE Chemistry Paper 2 Unofficial Mark Scheme 2016 Watch

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    (Original post by Droneon)
    Is it ok if I put remains 'brown' instead of 'orange' for the bromine water question?


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    Anyone? That's question 5c


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    (Original post by rcmack)
    Edexcel iGCSE Chemistry Paper 2C 15 June, sorry should have specified in the question...
    Please send the answers and the question numbers you remember
    Please also point out any mistakes or mistakes in question numbers

    1a) Glass rod / stirrer and Bunsen Burner
    1b) Liquids that dissolve is solvent
    1c) Colourless liquid is solution
    1d) Solid insoluble impurities removed in stage 2 (filtration), salt crystals removed in stage 3 (crystallisation)
    1d) Crystallisation point is when crystals begin to form
    1e) Water evaporates from the heat

    2a) Water levels rose as oxygen in air reduced as it reacted with iron to produce hydrated iron oxide, stopped as all oxygen had been used up
    2b) Cant remember what it asked but it was:
    iron? + sulphuric acid? -> iron sulphate + hydrogen
    2c) 2HNO3 + CuO -> Cu(NO3)2 + H2O
    2d) Warmed acid as it increased rate of reaction
    2e)In excess when solid starts to form at the bottom (stops dissolving)

    3a) Metal oxide is alkaline (e.g. sodium hydroxide) and non metal oxides are acidic (e.g. sulphur dioxide)
    The question asked for the element that would form oxides, so any metal (sodium, magnesium etc.) is correct for the first one, and any non metal apart from argon is correct for the second one. you did not have to specify the oxide, i.e. magnesium oxide, sulphur dioxide etc.
    3b) Dot cross diagram of MgCl with each with a full outer shell, and chloride ions with one donated electron, charges where Mg2+ and Cl- x2
    3c) Ionic bonding is transfer of electrons, producing a positive and negative ion(s), with electro-static forces of attraction between oppositely charged ions
    3d) Why ionic is strong: strong electro-static forces between oppositely charged ions which need a lot of energy to break

    4a) Titration
    4b) Pipette to add 25cm3
    4c) Methyl orange is yellow before, orange OR red when neutral
    4d) Fe2+ gives green precipitate, Fe3+ gives brown(/orange) precipitate
    4e) Burrette readings, can't remember exact values but values had to be given to 2 decimal places
    4f) 22.60, 22.45, 22.55 for the concordant results in boxes 2, 3, 4 with an average of 22.533....., 22.53 to have 2dp, like the given results


    5a) Isomer has the same chemical formula but different structural formula
    5b) Isomer of with 4 carbons and 8 hydrogens with a double bond
    5c) Test with bromine water, which goes colourless in the one with a double bond (but-1-ene i think?) and stays orange in the other one
    5d) CH3-CH2-CH2-OH
    5e) Cant remember the monomer but ( )n with the double bond broken and carbon bonds outside brackets

    6a) Refinery gas has lowest boiling point, bitumen was most viscous
    6b) Long chain hydrocarbon -> C10H20 and x number of ethene
    6c) Cracking is important as shorter chain hydrocarbons are in higher demand, as they are used for cars (i.e. gasolene etc..)
    6d) Long Hydrocarbon + Oxygen --> Carbon, Carbon Monoxide, Carbon Dioxide and Water
    i think it is C8H18 + 6O2 > 6C + CO2 + CO + 9H2O, variants without Carbon may be accepted

    7a) 2.75g
    7b) Using 0.0625 moles from A, 1500 cm3 of Carbon Dioxide

    cant remember question number but:

    3:1 ratio electrons:Al so 20/3 moles of Al
    mass= moles x mr so 6.666 x 27 = 180g






    Hope this mark scheme helped!!! Good luck in Triple Physics and the rest of your exams!
    Aren't there like 8 questions I thinks u missed a question the Faraday one ??
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    (Original post by aaljhfgahsj)
    Yeah i know now lol, thing is though, I always remember when i see the word 'mean' to give the exact answer, cause in maths igcse you are not supposed to round the answer if it asks for the mean - it should be the exact figure
    I mean if u only had a dot above the 3 then dont worry they probably wont notice it.
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    (Original post by Droneon)
    Anyone? That's question 5c


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    I have solved a similar question in a past paper and brown was ignored in the mark scheme.
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    (Original post by shahida sulaiman)
    Aren't there like 8 questions I thinks u missed a question the Faraday one ??
    It's the bottom part the 180g he just doesn't know the question number.


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    (Original post by Droneon)
    Anyone? That's question 5c


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    Essentially it stays the same colour which is usually orange/brown. You should be okay. Will probably allow "red/orange/yellow/brown in any combination"
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    (Original post by Abodee1)
    I mean if u only had a dot above the 3 then dont worry they probably wont notice it.
    Yeah that's what I meant
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    Does anyone know how many marks the incomplete combustion equation question was??
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    (Original post by Emilia1479)
    Does anyone know how many marks the incomplete combustion equation question was??
    the equation question was just 1 I believe
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    (Original post by Vigster)
    the equation question was just 1 I believe
    2 marks* one for the right reactants and products , and one for the correct balancing.
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    Okay thanks
    (Original post by Vigster)
    the equation question was just 1 I believe
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    for the dot and cross diagram I forgot to put the 8 electrons on the mg, but did it for everything else. what would I get /3?
    thanks
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    Oh okay thank you

    Do you know what the reactants and products were?? I'm pretty sure I managed to balance it wrong... 😡

    (Original post by Abodee1)
    2 marks* one for the right reactants and products , and one for the correct balancing.
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    Um... I'm pretty sure they would accept no electrons as I've seen it in the textbook (I think)

    (Original post by Hsevras)
    for the dot and cross diagram I forgot to put the 8 electrons on the mg, but did it for everything else. what would I get /3?
    thanks
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    Will I lose the marks for the colours of the Fe2+/3+ ions if I just said the colours, without saying precipitate? Gah what a silly thing to do. Oh well - only two marks.
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    GUYZ .. there was 1 question about incomplete combustion of hydrocarbon.... we needed to give the products... i was hard to balance also..

    what are the products.... water and carbon ( soot) OR WATER AND CARBON MONOXIDE;//.
    I WROTE THE CO....but my friend says it will be this.

    Reactants-----> C + CO + H20..... dont look for balancing...sample ...i think this is wrong... only CO must be there
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    (Original post by PlinyTheElder)
    And then to any other duty delegated to him...

    I think the equation was "C18H38 ----> C10H20 + #" so wouldn't # just be C8H18?
    Yeah that's what I got as well. Did the question say the product had to be ethene?
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    (Original post by Helper OF ALL)
    GUYZ .. there was 1 question about incomplete combustion of hydrocarbon.... we needed to give the products... i was hard to balance also..

    what are the products.... water and carbon ( soot) OR WATER AND CARBON MONOXIDE;//.
    I WROTE THE CO....but my friend says it will be this.

    Reactants-----> C + CO + H20..... dont look for balancing...sample ...i think this is wrong... only CO must be there
    I also wrote CO + H2O, but apparently it's C + CO + CO2 + H2O...
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    (Original post by PlinyTheElder)
    And then to any other duty delegated to him...

    I think the equation was "C18H38 ----> C10H20 + #" so wouldn't # just be C8H18?
    im pretty sure that cracking alkenes always produces a certain number of ethene, but im not sure!
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    (Original post by rcmack)
    im pretty sure that cracking alkenes always produces a certain number of ethene, but im not sure!
    I think cracking alkanes always gives at least one alkene, not necessarily always ethene.
 
 
 
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