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AQA CHEM5 A2 Chemistry - 19th June 2013

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In terms of periodicity and burning flames and fumes what do we need to know exactly!
Reply 1521
Avatar for im7
im7
2
Original post by flyylikejetz
In terms of periodicity and burning flames and fumes what do we need to know exactly!


Sodium burns with a yellow flame
Magnesium burns with a bright white flame
Sulfur burns with a blue flame
Phosphorus burns with a white flame

I can't think of any others though
Guys how would you do question 4biv and 4c??? and 5bii and 5cii???
i have no ideaaa :frown:
questions.rtf105.3KB
Original post by _jamie
The bidentate ligand H2NCH2CH2NH2


eg

[Cu(H2O)6]2+ + 3H2NCH2CH2NH2 --> [Cu(H2NCH2CH2NH2)3]2+ + 6H2O


3+ ions one is a strange one, eg

2[Al(H2O)6]3+ +3H2NCH2CH2NH2 --> 2[Al(H2O)3(OH)3]+ + 3[H3NCH2CH2NH3]2+

They asked this back in 2012
Reply 1524
Avatar for Zytex
Zytex
Original post by flyylikejetz
In terms of periodicity and burning flames and fumes what do we need to know exactly!


Attached is the flames
periodicity flames.png9.6KB
Original post by im7
Sodium burns with a yellow flame
Magnesium burns with a bright white flame
Sulfur burns with a blue flame
Phosphorus burns with a white flame

I can't think of any others though


Na- Yellow flame
Mg to Phosphorous- White flame and White fumes
Sulphur- Blue flame and choking gas

For the bits highlighted in bold, there are other acceptable answers.
Reply 1526
Avatar for _jamie
_jamie
4
Original post by 16dan2life
eg

[Cu(H2O)6]2+ + 3H2NCH2CH2NH2 --> [Cu(H2NCH2CH2NH2)3]2+ + 6H2O


3+ ions one is a strange one, eg

2[Al(H2O)6]3+ +3H2NCH2CH2NH2 --> 2[Al(H2O)3(OH)3]+ + 3[H3NCH2CH2NH3]2+

They asked this back in 2012


Thank you!
Can someone help with the born haber cycle?
Reply 1528
Avatar for BerryB
BerryB
January 2010 paper. Question 3c.
http://filestore.aqa.org.uk/subjects/AQA-CHEM5-W-QP-JAN10.PDF
The answer is:
Pt|H2(g)|OH(aq),H2O(l)||O2(g)|H2O(l),OH(aq)|Pt
but i dont understand why the OH and H2O are seperated with commas instead of lines, because they are different phases, arent they?
Reply 1529
Avatar for crc290
crc290
14
Original post by BerryB
January 2010 paper. Question 3c.
http://filestore.aqa.org.uk/subjects/AQA-CHEM5-W-QP-JAN10.PDF
The answer is:
Pt|H2(g)|OH(aq),H2O(l)||O2(g)|H2O(l),OH(aq)|Pt
but i dont understand why the OH and H2O are seperated with commas instead of lines, because they are different phases, arent they?


Aqueous isn't really a phase of its own - its still liquid
Reply 1530
Avatar for AmyLH
AmyLH
10
It doesn't matter if we put lines instead of commas does it? Our teacher just told us to put lines as they still accept it on the mark scheme.
Original post by AmyLH
It doesn't matter if we put lines instead of commas does it? Our teacher just told us to put lines as they still accept it on the mark scheme.


I put lines if they change state, comma if they are the same state.

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Reply 1532
Avatar for BerryB
BerryB
Original post by crc290
Aqueous isn't really a phase of its own - its still liquid


Oh okay thank you
Reply 1533
Avatar for simanana
simanana
Original post by edward28
Well on page 189 it explains why aluminum oxide has extra covalent bonding. But then on page 190 it shows that magnesium oxide has the highest melting point.


yes, the extra covalent bonding is what actually makes it have the higher melting point...cause theyres stronger bonds... or something like that haha
Original post by AmyLH
It doesn't matter if we put lines instead of commas does it? Our teacher just told us to put lines as they still accept it on the mark scheme.


I've seen on mark schemes that they accept commas instead of lines, vice versa. So it doesn't matter
Reply 1535
Avatar for BerryB
BerryB
Suggest why the electron affinity of chlorine is an exothermic change?
Does anyone know how to answer this?
Original post by BerryB
Suggest why the electron affinity of chlorine is an exothermic change?
Does anyone know how to answer this?

Attraction between the +ve nucleus and the -ve electron me thinks
Reply 1537
Avatar for popnit
popnit
14
Original post by lifeisgood2012
Guys how would you do question 4biv and 4c??? and 5bii and 5cii???
i have no ideaaa :frown:


I think emf would increase but can't really explain it very well..basically the eqm will shift to the right to oppose the change. Is the answer increase?
Reply 1538
Avatar for popnit
popnit
14
What would you guys give as a reason why TM are coloured? I just want a standard answer. Say for example if it was a 2 mark question.
Hi
Could anyone help me with this question - http://filestore.aqa.org.uk/subjects/AQA-CHEM5-QP-JUN12.PDF, question 2B.
The answer is 0.098kJ K-1 mol-1 and -∆S/∆S but I don't understand why and how.

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