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

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Original post by defenestrated
wait were they both the same solution??


I thought they were both HCl, but I misread loads of questions on that paper so idk..
Original post by jamesj477
I thought they were both HCl, but I misread loads of questions on that paper so idk..


Yes they were, but different concentrations
Original post by conradliebers
Yes they were, but different concentrations


omg do you know this for definite?????

SFDHGHDEJEWKEFNVGFDS I SAID ONE WAS MORE REACTIVE THAN THE OTHER
i thought they were different solutions :frown:

why do i NEVER READ THE QUESTION
Original post by defenestrated
omg do you know this for definite?????

SFDHGHDEJEWKEFNVGFDS I SAID ONE WAS MORE REACTIVE THAN THE OTHER
i thought they were different solutions :frown:

why do i NEVER READ THE QUESTION


It was because it said they were both Hal, so if one had less of a temperature rise, it was due to a lower concentration as the same volume of acid was added.
For 3f, I swear it was a trick question about protons because protons only exist in the nuclear and it was on about the outer shell which was electrons....anyone else agree? I put nothing because there aren't protons present
All wrong
https://www.youtube.com/watch?v=iygdPjtFu28
Original post by Tash Lewis
For 3f, I swear it was a trick question about protons because protons only exist in the nuclear and it was on about the outer shell which was electrons....anyone else agree? I put nothing because there aren't protons present


The number of electrons = the number of protons
Original post by Himtiaz


Why are you putting a link to a mark scheme of a different exam board?
Original post by conradliebers
It was because it said they were both Hal, so if one had less of a temperature rise, it was due to a lower concentration as the same volume of acid was added.


how many marks was that question do you remember
i think they screwed up a little with the solid x y z bit

calcium hydroxide reacts with c02 to form calcium carbonate ... however this also produces water which it didnt put in another box, yet in all the other equations it did... that's why i am some others thought it was suitable to write calcium hydrogen carbonate since that seemed the most suitable considering the circumstance.

i think they will realise their mistake and award a mark for both calcium carbonate and calcium hydrogen carbonate
someone pls put me out of my agony!
1. Can O2 be found in unpolluted air??
2. for the calcium experiment, could you have written calcium carbonate instead of calcium hydrogen carbonate?
Thank you!
Original post by defenestrated
how many marks was that question do you remember


2 marks.
Original post by pixiedust16
someone pls put me out of my agony!
1. Can O2 be found in unpolluted air??
2. for the calcium experiment, could you have written calcium carbonate instead of calcium hydrogen carbonate?
Thank you!


1. No, it asked for a compound.
2. It is CaCO3.
What do you think the grade for an A will be?
4 (f) is incorrect

The acid is already in excess and so the temperature will not be affected. Therefore there is no temperature change in comparison to experiment 1.
Original post by Togarty12
4 (f) is incorrect

The acid is already in excess and so the temperature will not be affected. Therefore there is no temperature change in comparison to experiment 1.


I already went through this. They doubled to volume of acid used, so even though its already in excess, because the reaction will give of the same amount of energy, because the volume has doubled, it requires more energy for the same increase in temperature, so the rise in temperature is less.
Original post by conradliebers
I already went through this. They doubled to volume of acid used, so even though its already in excess, because the reaction will give of the same amount of energy, because the volume has doubled, it requires more energy for the same increase in temperature, so the rise in temperature is less.


that makes no sense?
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Avatar for Gdmn
Gdmn
1
I said one was more acidic than the other so it provided a more vigorous neutralization reaction for the solution x and y thing
I thought if at 25cm3 was in excess, all the magnesium has reacted, adding more acid doesn't change that, all the magnesium will react at the same rate the same way. increasing heat given out can only be affected by the mass of magnesium used.

someone explain i am probs wrong

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