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Edexcel IGCSE Chemistry May 2015 (14th)

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Is exothermic, or giving heat energy off an observation?
what did you put for the question about Solid A in the hydrogen peroxide question?
Reply 61
Avatar for torilee
torilee
9
Original post by AlSahHim
Is exothermic, or giving heat energy off an observation?
what did you put for the question about Solid A in the hydrogen peroxide question?

What was the question? I don't remember it :confused:
It was a ... paper all the questions were repeated wish i could have payed attention to the pastpaper questions.The last question got me totally nuts like oh god and i missed the whole moles question though it was easy i think i lost my 5 marks there and the last mass question didnt know that actually i suck at calculations and lost some marks in the pressure question and obviously some other marks here and there like i dont know i was so tensed that i forgot the observations for magnesium reacting with oxygen lol.Should get 80+ btw can anyone here please solve that whole alkanes alkenes question here,the reactions and all :smile:
Reply 63
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an123._
In the moles question, did you multiply the NaOH by 3 as the equation stated it had 3 moles?
Reply 64
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SIZ99
Original post by an123._
In the moles question, did you multiply the NaOH by 3 as the equation stated it had 3 moles?

We had to divide by 3.
Reply 65
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kunikos
The NaOH was the one where you had to work out concentration and amounts of moles? I'm pretty sure, if it was the first question was 0.045 and the second was 0.015 or maybe a zero out I can't remember. Then the concentration was 0.0530 mol/dm³. You did volume of the naoh in dm³ which was amount in cm³/1000 then multiply by the concentration which was 0.180mol/dm³. Then itbwas 3NaOH + the acid which means that one mole of acid reacts with 3 moles of sodium hydroxide. Ratio is 3:1 which is the same as 0.045:0.015 so the amount of acid on moles was 0.015 (can't remember what acid it was)
Reply 66
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Ijazx1
4
Yeah you have to divide the answer of part 1 by 3 as ratio was 3:1
Posted from TSR Mobile
Reply 67
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l.coxx
2
what did everyone put for the bromine question at the front and the one where it asked how gas particles were arranged?
Reply 68
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l.coxx
2
and the empirical formula question??
Can anyway remember the last question pressure one and the nitric acid one ?
Reply 70
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l.coxx
2
on the cold water in the conical flask one was it boiling and condensing or evaporating and condensing
Reply 71
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l.coxx
2
Original post by PalwashaAyubb
Can anyway remember the last question pressure one and the nitric acid one ?


i thought the nitric acid was to remove carbonate ions and their weren't any in the equation
Original post by l.coxx
i thought the nitric acid was to remove carbonate ions and their weren't any in the equation

The question was something like why we dont put in nitric acid first
Reply 73
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kunikos
Original post by l.coxx
and the empirical formula question??


To do that one you had to divide the percentages by the ram and you got a ratio of 3:6:3 which in empirical formula os 1:2:1 so the formula was CH2F and then the molecular was C2H4F2 because the rfm lf the empirical was 33 which goes twice into the actual RFM which was 66
How did everyone find 1C?
Original post by l.coxx
on the cold water in the conical flask one was it boiling and condensing or evaporating and condensing


I crossed Part A dont remember what that was
Original post by JHorsnall
How did everyone find 1C?

Hm it was fine but paper 2 shall give us a tough time
Reply 77
Avatar for kunikos
kunikos
Original post by l.coxx
on the cold water in the conical flask one was it boiling and condensing or evaporating and condensing


Evaporating and condensing, boiling has to be 100°c
Original post by l.coxx
on the cold water in the conical flask one was it boiling and condensing or evaporating and condensing


It was evaporating and condensing, I believe. Boiling, I think, only occurs when you apply heat to it. It was cold water, closed off with a bung, and left for a few minutes (?).

Correct me if I'm wrong.
Trust me whoever did pastpapers would easily get an A* i guess A this time will be 125-130/180

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