2016 IGCSE Chemistry Paper 2 Unofficial Mark Scheme 2016

Is it ok if I put remains 'brown' instead of 'orange' for the bromine water question?


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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!

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

Anyone? That's question 5c


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Aren't there like 8 questions I thinks u missed a question the Faraday one ??

Anyone? That's question 5c


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I mean if u only had a dot above the 3 then dont worry they probably wont notice it.

Does anyone know how many marks the incomplete combustion equation question was??

the equation question was just 1 I believe

the equation question was just 1 I believe

2 marks* one for the right reactants and products , and one for the correct balancing.

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

And then to any other duty delegated to him...

I think the equation was "C18H38 ----> C10H20 + #" so wouldn't # just be C8H18?

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

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!