Unit5/unit 4 chemistry - EDEXCEL June 2012
Chemistry exam discussion - share revision tips in preparation for GCSE, A Level and other chemistry exams and discuss how they went afterwards.
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012your not required to know why they are coloured. It's not required for our syllabus.(Original post by iesians)
no ! i know why transition metal and their complexed are coloured.
i wanna know why are AZO DYES coloured .
the book just says ..."extensive electron bonding in N=N group'" i dont get it ..?!
Sorry if im patronising but you don't need to know. There might be some articles on the internet which could explain it, if your that curious....... -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012i was just concerned they may ask about it , its okay. i have one more question....why is phenylamine more soluble in water than butylamine..?!(Original post by James A)
your not required to know why they are coloured. It's not required for our syllabus.
Sorry if im patronising but you don't need to know. There might be some articles on the internet which could explain it, if your that curious.......
sorry if im annoying ya
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012....(Original post by iesians)
i was just concerned they may ask about it , its okay. i have one more question....why is phenylamine more soluble in water than butylamine..?!
sorry if im annoying ya
Last edited by Jukeboxing; 17-05-2012 at 20:07. Reason: Misread question. -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012Phenylamine has an -OH group?(Original post by Jukeboxing)
I'm guessing its because phenylamine can form more hydrogen bonds(dimers) with water, as it has an -OH group and an amino group where as butylamine just has an amino group.
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012OMG im so sorry i confused you with the question ! i had to ask why is phenylamine LESS soluble than butylamine !! SORRY(Original post by Jukeboxing)
I'm guessing its because phenylamine can form more hydrogen bonds(dimers) with water, as it has an -OH group and an amino group where as butylamine just has an amino group.
and i think you are confused between phenylamine and phenol.... -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012In that case, the large non-polarity of phenyl makes it less soluble.(Original post by iesians)
OMG im so sorry i confused you with the question ! i had to ask why is phenylamine LESS soluble than butylamine !! SORRY
and i think you are confused between phenylamine and phenol....
Sorry about my error earlier. -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012so what do we write ..?! that the london forces between phenylamine and water molecules do not release enough energy to break down existing hydrogen bonds between water molecules ??!(Original post by Jukeboxing)
In that case, the large non-polarity of phenyl makes it less soluble.
Sorry about my error earlier. -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012The benzene rings breaks more H bonds between H2O than are formed between the amino group and H2O, and water molecules disrupt van der waal forces between phenylamine molecules.(Original post by iesians)
so what do we write ..?! that the london forces between phenylamine and water molecules do not release enough energy to break down existing hydrogen bonds between water molecules ??!
All that is energetically unfavourable, making it less soluble.
From Chemguide -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012i dont geh it !!(Original post by Jukeboxing)
The benzene rings breaks more H bonds between H2O than are formed between the amino group and H2O, and water molecules disrupt van der waal forces between phenylamine molecules.
All that is energetically unfavourable, making it less soluble.
From Chemguide
does the lone pair on Nitrogen atom get involved in benzene's delocalised electron system , and thus strong hydrogen bonds cannot be made between phenylmine and water molecules ....?!!?! -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012Have a look here:
http://www.chemguide.co.uk/organicpr...ackground.html -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012how do we know if we have to use a burette or a pipette ?! in jan 2012 they asked ..
what would be the most suitable peice of apparatus to remove 10cm3 of sample form the solution?
i thought it could be both burette and pipette, but in the mark scheme answer was PIPETTE and BURETTE was in the reject list ..!! -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012This is the EDEXCEL thread.(Original post by IqraAli)
Can someone please post the link for the jan 2012 F332 salters B paper pls -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012the lone pair of the nitrogen atom does get involved in 'activating' the benzene ring, but this in effect makes the nitrogen atom less delta negative, hence less strong hydrogen bonds occur between water molecules.....(Original post by iesians)
i dont geh it !!
does the lone pair on Nitrogen atom get involved in benzene's delocalised electron system , and thus strong hydrogen bonds cannot be made between phenylmine and water molecules ....?!!?! -
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012ahaan i see someones alive here ...(Original post by James A)
the lone pair of the nitrogen atom does get involved in 'activating' the benzene ring, but this in effect makes the nitrogen atom less delta negative, hence less strong hydrogen bonds occur between water molecules.....
thank you very much, i think i got it ..! 
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012nice!(Original post by iesians)
ahaan i see someones alive here ... thank you very much, i think i got it ..!
I'm currently doing a little biology revision, but it's nice to ocassionally pop back on this thread to refresh my mind on chemistry.
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012hmmmm i reckon biology unit 5 ..?!(Original post by James A)
nice!
I'm currently doing a little biology revision, but it's nice to ocassionally pop back on this thread to refresh my mind on chemistry.
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Re: Unit5/unit 4 chemistry - EDEXCEL June 2012yhh, so much to revise!!(Original post by iesians)
hmmmm i reckon biology unit 5 ..?!
I'm giving these exams by best shot and after that, I deserve such a nice break!
thank you very much, i think i got it ..! 
