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Edexcel A2 Chemistry Exams -6CH04 (14th June) and 6CH05 (22nd June) Discussion Thread

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Well **** it's now less than a day away lol. Time flies.
@Don Pedro K. The voltmeter has to have high current so that it doesn't draw in current.

****, i am flunking tomorrow :lol:
June 2014 was a horrible paper wasn't it? I found it extremely tough
Original post by Blazyy
- Benzene does not decolourise bromine water because it doesn't undergo an addition reaction(because this would involve breaking up the delocalised system). However phenol reacts by addition reaction, the reason is because of the OH group which increases the electron density and makes it more susceptible to attack from electrophiles.

Screenshot_1.png <--- Click to enlarge

- Benzene burns with a smoky flame because it's carbon to hydrogen ratio is very low. Basically, lower the ratio, sootier the flame.

- I'm sorry I don't know because it's not in the spec :colondollar:


Surely the C : H ratio is very high in benzene (i.e. lot more C than H), which causes the sooty flame?
predictions for what is most likely to come up?
Original post by Ayman!
@Don Pedro K. The voltmeter has to have high current so that it doesn't draw in current.

****, i am flunking tomorrow :lol:


Haha I just want to get chemistry out of the way xD

Original post by Whizbox
June 2014 was a horrible paper wasn't it? I found it extremely tough


I'm about to do that today...wish me luck lol!
Original post by Don Pedro K.
Surely the C : H ratio is very high in benzene (i.e. lot more C than H), which causes the sooty flame?


Benzene is C6H6. Ratio is 1:1 which is very low.
Original post by Blazyy
Benzene is C6H6. Ratio is 1:1 which is very low.


oh yeah okay ahah
Original post by Don Pedro K.
Haha I just want to get chemistry out of the way xD



I'm about to do that today...wish me luck lol!


Let me know how you get on, it's scary
I have a gut feeling something on Organic Synthesis will come up where they ask you to describe a whole method - like Steam distillation or Solvent extraction. I really hope not though! I hate organic synthesis with passion 😓
Original post by MacroniCheese
I have a gut feeling something on Organic Synthesis will come up where they ask you to describe a whole method - like Steam distillation or Solvent extraction. I really hope not though! I hate organic synthesis with passion 😓


If something related to ligands comes up I will sue Edexcel
Original post by Don Pedro K.
Surely the C : H ratio is very high in benzene (i.e. lot more C than H), which causes the sooty flame?


Original post by Blazyy
Benzene is C6H6. Ratio is 1:1 which is very low.


Would discussing the necessary moles of oxygen required to burn one mole of benzene for COMPLETE combustion not be a better way of explaining the sooty flame?

C6H6 + 7.5O2 --> 6CO2 + 3H2O
(edited 7 years ago)
Original post by Whizbox
June 2014 was a horrible paper wasn't it? I found it extremely tough


Yes it was. Just a lot of annoying questions
@Ayman! @C0balt can you guys explain why the lines are in the order that they are? I thought that since benzene = -205 or whatever it was and structure X (Kekulé) = -354 (3 * -118), shouldn't the line for X be below that of benzene??

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Original post by Ayman!
@Don Pedro K. The voltmeter has to have high current so that it doesn't draw in current.

****, i am flunking tomorrow :lol:

You mean high resistance
Original post by Whizbox
June 2014 was a horrible paper wasn't it? I found it extremely tough

I agree
Also, thermodynamically stable is when delta S total < 0, and kinetically inert = high activation energy, right?
Original post by Wunderbarr
Would discussing the necessary moles of oxygen required to burn one mole of benzene for COMPLETE combustion not be a better way of explaining the sooty flame?

C6H6 + 15O2 --> 6CO2 + 3H2O


Forgive me if I'm wrong, but how does oxygen have anything to do with a flame being sooty? Soot = Carbon. Oxygen plays no part here.
Original post by Don Pedro K.
@Ayman! @C0balt can you guys explain why the lines are in the order that they are? I thought that since benzene = -205 or whatever it was and structure X (Kekulé) = -354 (3 * -118), shouldn't the line for X be below that of benzene??

Attachment not found




Capture.JPG

Lower the energy the more stable it is
Hi everyone, would appreciate if anyone can help me out in these mcqs:

1. If the temperature of of the nitration of benzene is allowed to rise too high, dinitration and trinitration can occur. This is the evidence that the:
A) nitro group is electron withdrawing
B) nitro group is electron donating
C) delocalisation energy of nitrobenzene is greater than that of benzene.
D) delocalisation energy of nitrobenzene is less than that of benzene.
Why is the answer A? I thought it was B.

2. June 2015 IAL Q17 Why is the answer B?
Doing IAL June 2015 and starting to feel the panic

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