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

1. (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 554341554343

Attachment 554341
Because cyclohexane is at the bottom, so to go from benzene to it is -205ish whereas from X is -360ish so bigger jump. If you took cyclohexane as your 0, then by definition upwards benzene is at +205 and x is at +360
2. (Original post by C0balt)
You mean high resistance

I agree
Yeah woops

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3. (Original post by Blazyy)
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.
The fact that one mole of benzene requires 15 moles of oxygen should sound TOO DAMN HIGH.

It cropped up in one of my lessons and it is said that complete combustion of benzene won't always occur because of this.
So instead of complete combustion you get incomplete combustion, hence the production of our favourites: carbon (and carbon monoxide).
4. (Original post by Blazyy)
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.
Because you only get carbon when there isn't enough oxygen to react with it to form co2. So if it requires a huge amount of oxygen to burn completely, it's more likely that there won't be enough oxygen available
5. (Original post by Wunderbarr)
The fact that one mole of benzene requires 15 moles of oxygen should sound TOO DAMN HIGH.

It cropped up in one of my lessons and it is said that complete combustion of benzene won't always occur because of this.
So instead of complete combustion you get incomplete combustion, hence the production of our favourites: carbon (and carbon monoxide).
I think I was wrong...
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6. (Original post by Blazyy)
I think I was wrong...
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It's all right

We're all here to learn.
7. Has chromium chemistry come up in much of the recent past papers? As well as uses of transition metals in industry? Could be something to revise if not.
8. Oh my god unit 5 papers are so longgggggg

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9. Do we need to know how to prepare cholesteryl benzoate and methyl 3-nitrobenzoate. Its in the cgp but its never come up in papers
10. (Original post by DonPedrodoc)
Do we need to know how to prepare cholesteryl benzoate and methyl 3-nitrobenzoate. Its in the cgp but its never come up in papers
Let's hope not
11. (Original post by DonPedrodoc)
Do we need to know how to prepare cholesteryl benzoate and methyl 3-nitrobenzoate. Its in the cgp but its never come up in papers
I'm pretty sure we don't need to know it although check the spec just in case
12. (Original post by Blazyy)
I'm pretty sure we don't need to know it although check the spec just in case
It says we do on the spec
13. Do you guys time yourself when you the past paper? I have never finish on time when I do lol . I am really worried I will run out of time tomorrow.
14. Why is Sulfuric Acid needed when oxidizing alcohols?
15. (Original post by DonPedrodoc)
Do we need to know how to prepare cholesteryl benzoate and methyl 3-nitrobenzoate. Its in the cgp but its never come up in papers
It's in the spec and I don't think I've come across it in past papers. Knowing Edexcel it's probably better to be familiar with those preparations
16. (Original post by DonPedrodoc)
Do we need to know how to prepare cholesteryl benzoate and methyl 3-nitrobenzoate. Its in the cgp but its never come up in papers
what page cgp??
17. (Original post by Bertie Paterson)
Why is Sulfuric Acid needed when oxidizing alcohols?
ensures theres enough H+ ions to oxidise the alcohol
18. (Original post by Rahatara Sadique)
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?
Bump
19. Which of the following reagents would enable you to separate iron(III) hydroxide from amixture of iron(III) hydroxide and copper(II) hydroxide?
A Dilute hydrochloric acid
B Aqueous ammonia
C Dilute nitric acid
D Sodium hydroxide solution
20. (Original post by Bertie Paterson)
Bump
I got that wrong but I think it's because the nitrogen has a lone pair which can be delocalised into the ring and making the ring more susceptible to further electrophilic attack

Edit
I'm wrong ignore me thanksss

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