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Aqa chem 4/ chem 5 june 2016 thread

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Original post by 12284
No you don't need to include it.
And yep it is on the spec but I haven't seen a question on it yet.


What do we need to know about the M+1 peak?
Original post by Kaya22
if you divide by the volumes you get the wrong ph


well i got the correct answer when dividing by the new total volume 1.005dm-3
Original post by Guls
Na2CO3 + HCl NaCl + NaHCO3
NaHCO3 + HCl NaCl + H2O + CO2
The conjugate acid produced from the first equation is so weak that it can accept another proton to form NaCl creating two concentrations of where the [OH]=[H+]


I think I kind of get that :s-smilie:

But then how this gets the moles of ethanediocacid I don't know
Original post by dingdon
how did you know where double bond goes?


it will go to where there is a hydrogen on the adjacent carbon to C-OH. Hard to explain. I'll draw a quick diagram hold on
Reply 424
Original post by Sniperdon227
well i got the correct answer when dividing by the new total volume 1.005dm-3


my calculator played up like 5 times ahaha i knew exactly what i was doing but my i hope my calculator doesnt do that in the exam!
Original post by dingdon
how did you know where double bond goes?


well it cant be c-c-c=cooh because the 1st carbon counting from the c in cooh would have 5 bonds so it can only be c-c=c-cooh
For questions that ask for equations, particularly fragmentation equations, I always end up drawing out the compound (instead of writing CH3CH2CH2 etc.) will I lose marks?????????
Original post by dingdon
how did you know where double bond goes?




The arrow from the OH bond is where the double dond would be. In other compunds there could be multiple places the double could go which leads to isomers
Original post by dingdon
how did you know where double bond goes?


draw out both scenarios and you'll see
Original post by lahigueraxxx
For questions that ask for equations, particularly fragmentation equations, I always end up drawing out the compound (instead of writing CH3CH2CH2 etc.) will I lose marks?????????


No
Original post by SirRaza97
No


phew, thank you!
Original post by lahigueraxxx
phew, thank you!


Sometimes they specifically want a displayed formula as well so it's safe to do so. Unless they speficially ask for the structural formula then you should be ay-okay
Original post by lahigueraxxx
For questions that ask for equations, particularly fragmentation equations, I always end up drawing out the compound (instead of writing CH3CH2CH2 etc.) will I lose marks?????????


they are never clear what they want, whether that be the structural formula or displayed, so i think both are accepted
(edited 7 years ago)
Original post by Sniperdon227
they are never clear what they want, whether that be the structural formula or displaced, so i think both are accepted


awesome, thank you! No they are never clear but it would be really annoying to get marked down on something like that
Original post by SirRaza97
Sometimes they specifically want a displayed formula as well so it's safe to do so. Unless they speficially ask for the structural formula then you should be ay-okay


Will keep that in mind - thanks again!
http://filestore.aqa.org.uk/subjects/AQA-CHEM4-QP-JUN12.PDF

4fii it asks about indicators' colour change, without telling us any detail about its colour in acid or alkali, are we supposed to memorise that?
What are the predictions for this year?
I don't understand what they could ask about gas chromatography? Any guesses
Original post by Seclusion
http://filestore.aqa.org.uk/subjects/AQA-CHEM4-QP-JUN12.PDF

4fii it asks about indicators' colour change, without telling us any detail about its colour in acid or alkali, are we supposed to memorise that?


Supposed to know the Phenolpthalein and Methyl Orange colour changes.
Original post by Seclusion
http://filestore.aqa.org.uk/subjects/AQA-CHEM4-QP-JUN12.PDF

4fii it asks about indicators' colour change, without telling us any detail about its colour in acid or alkali, are we supposed to memorise that?


you should know the colours of phenopthalein and methyl orange in acid and alkali
Original post by Parallex
Supposed to know the Phenolpthalein and Methyl Orange colour changes.


Original post by Sniperdon227
you should know the colours of phenopthalein and methyl orange in acid and alkali


Ah! Thank you. It's just that I don't see it on the spec? Maybe I am missing it?

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