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2016 IGCSE Chemistry Paper 2 Unofficial Mark Scheme 2016

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Avatar for C_Yap
C_Yap
17
For me, worst case scenario would be 52/60, so yay :smile:

Btw, I put orange instead of red, because the question said 'neutralised', and it only turns red when acidic.

And omds :h:, the titration came up like the 4th year in a row, so it is like getting 8 free marks.
Original post by IGCSETANK
Anyone that put just CO2 and H2O got it wrong - the picture taken in the CGP is COMPLETE combustion - this asked for INCOMPLETE COMBUSTION. Aditionally red would be acceptable as I reviewed this w/ my teacher.


Guys supposing in the question it wrote that incomplete combustion produces carbon monoxide, its kinda obvious to include it in the equation lol
why did they heat the acid? was it to start the reaction or to increase the rate?
Original post by defenestrated
why did they heat the acid? was it to start the reaction or to increase the rate?


Increase rate, the same question was there in june 2015 1c.
Ok this has been annoying me, for the basic oxide and acidic oxide, i put sodium and chlorine respectively. Will i get marks?
Original post by Talkand...Talk
how much is an A*, i think i got 76%


Its going to be really high but not above 146.
Original post by rcmack
theres alot of questions missing from the mark scheme tho :/


thxs for reasurance :smile:
GUYS ON THE LAST PAGE, THERE WAS ONLY TWO QUESTIONS RIGHT

Like the two answer lines you put 2.75g and 1500cm3, you didn't have to right down the number of moles anywhere (apart from your working)
Reply 108
Avatar for rcmack
rcmack
OP
9
Original post by Castro300
Ok this has been annoying me, for the basic oxide and acidic oxide, i put sodium and chlorine respectively. Will i get marks?


since chlorine is a non-metal, it will produce an acid oxide, i just didnt put it in the exam as ive never heard of chlorine oxide
Original post by Abodee1
Its going to be really high but not above 146.


Damn it shouldn't go that high!! I would have though 140 is reasonable; like the papers weren't that easy
is silicion dioxide acidic?
Original post by Abodee1
Increase rate, the same question was there in june 2015 1c.


which paper? i just checked May 2015 it's not on there
Ok these are the questions im worried about, can anyone tell me the right answers:
Which stage insoluble impurities are removed in calcium oxide-i put 3

How do u know its in excess-i put solid formed at bottom

Why cracking is important, i put bigger demand for short chains and short chains more useful
Original post by Abodee1
im pretty sure its 8 because its an ion, it has lost its 2 outer electrons to form the outer shell and formed a shell with 8 electrons.


I think you can technically put either, I put 8 but im pretty sure I've seen mark schemes that accept both
Original post by Niclewis
Because it's methane...


Well I couldnt find any past papers with octane, but there's this webpage: http://chemistryhelp.net/basic-chemistry/941-chemical-monitoring-q-a and a few Yahoo Answers I found (while they are not necessarily reliable, many were in agreement), and probably several more sources if I could be bothered to look
Screenshot_2016-06-15-17-10-15.png
I think they will probably accept any balanced equation that has at least water and carbon monoxide
Original post by aaljhfgahsj
Damn it shouldn't go that high!! I would have though 140 is reasonable; like the papers weren't that easy


ikr!! Ifits 140 then i will prob get an A
Original post by Castro300
Ok these are the questions im worried about, can anyone tell me the right answers:
Which stage insoluble impurities are removed in calcium oxide-i put 3

How do u know its in excess-i put solid formed at bottom

Why cracking is important, i put bigger demand for short chains and short chains more useful


The insoluble impurities were removed at stage 2, as they were filtered out, leaving salt water.
Other 2 are correct
Original post by Niclewis
which paper? i just checked May 2015 it's not on there

http://qualifications.pearson.com/content/dam/pdf/Edexcel%20Certificate/Chemistry/2011/Exam%20materials/Question-paper-Paper-1C-June-2014.pdf
For "why do you heat the acid" i said to help the solid dissolve. Would i get it for that? And also for the excess one is it that the solid will sink to the bottom of the beaker?
It was 2014 june, my bad.

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