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Original post by Motorbiker
Find a carbon with four different groups.


Hint, one of the groups is a benzene ring and another is a H.

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Thanks!

I thought it was the carbon attached to the benzene ring which gives 4 groups. However, can carbon actually be attached to O (i.e. C-O bond) as one of the groups? I thought that each of the groups must be attached by a C-C bond
Original post by Motorbiker
Tbh I just completed a degree in chemistry and think memorization is how to do the exams even at a uni level.

There's a finite number of questions they can ask a finite number of ways. Memorise 98% then the stretch and extend questions you just hope for the best.

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I guess you're right; what do you mean by stretch and extend Q? The AQA ones?
Original post by ps1265A
Thanks!

I thought it was the carbon attached to the benzene ring which gives 4 groups. However, can carbon actually be attached to O (i.e. C-O bond) as one of the groups? I thought that each of the groups must be attached by a C-C bond


Yea, as long as it's a single bond the carbon can be bonded to anything.

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Original post by ps1265A
I guess you're right; what do you mean by stretch and extend Q? The AQA ones?


I think we had extra questions at a level, that were called stretch and extend. They were supposed to be slightly off syllabus but work out able.

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Original post by Motorbiker
Yea, as long as it's a single bond the carbon can be bonded to anything.

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Thanks!
Hi guys just wondering if anyone can help. I studied a b-tec at college a few years ago and now i have applied for chemistry at uni 2015 entry. As I didn't study a-level chem. I would like to know what a-level chem books to buy. I know it's AS and A2. Should I go for an AQA or an OCR etc. and which books would you recommend??

Thanks guys


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Original post by Ahhteeyah
Hi guys just wondering if anyone can help. I studied a b-tec at college a few years ago and now i have applied for chemistry at uni 2015 entry. As I didn't study a-level chem. I would like to know what a-level chem books to buy. I know it's AS and A2. Should I go for an AQA or an OCR etc. and which books would you recommend??

Thanks guys


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Well, any standard A Level textbook should do, tbh.

I'd also recommend this site: http://www.chemguide.co.uk
Original post by ps1265A
Thanks!

I thought it was the carbon attached to the benzene ring which gives 4 groups. However, can carbon actually be attached to O (i.e. C-O bond) as one of the groups? I thought that each of the groups must be attached by a C-C bond


You need to realise that each C atom has 4 electrons to share out in terms of bonds. Hence, Carbon can have a maximum of 4 bonds.

Hence, in an ester, the carbonyl carbon is bonded to an oxygen, and two other groups but it has 4 bonds (one double bond and two singles).
Original post by Motorbiker
I think we had extra questions at a level, that were called stretch and extend. They were supposed to be slightly off syllabus but work out able.

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Yeah it's off syllabus. :/

Sadly.
Can someone help me with this question?
d) 0.30 moldm-3 NH4Br (Ka of NH4+ = 5.6 x 10-10 moldm-3)

I'm struggling with the fact that they gave Ka of NH4+, wouldn't it be more useful if they gave Ka of NH4Br? And how do we use this... Ka of NH4+ = [H+][NH3]/[NH4+]... but how do we figure out conc of NH4+ in the first place?
Original post by ps1265A
Can someone help me with this question?
d) 0.30 moldm-3 NH4Br (Ka of NH4+ = 5.6 x 10-10 moldm-3)

I'm struggling with the fact that they gave Ka of NH4+, wouldn't it be more useful if they gave Ka of NH4Br? And how do we use this... Ka of NH4+ = [H+][NH3]/[NH4+]... but how do we figure out conc of NH4+ in the first place?


It looks challenging but can you post the full question by taking a photo?

It's because i get confused easily by these symbols. :smile:
This looks like a buffer question hang on...

Wait what's your question in the first place?
Original post by Jacksgap
It looks challenging but can you post the full question by taking a photo?

It's because i get confused easily by these symbols. :smile:


I'm sorry, I wrote this down in class :tongue:
Compound F contains C, H and O only and contains 54.2% oxygen by mass. The molar mass of compound F is 118g per mole. Using this info show that the molecular formula of compound F is C4H6O4. A2 chemistry question


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Have I got the structure correct? Thanks

edit: I can't seem to upload the pic just ignore this message
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(edited 9 years ago)
Original post by MissMedical
Have I got the structure correct? Thanks

edit: I can't seem to upload the pic just ignore this message
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You can describe the structure and the reasons you chose it.

E. G. Butanol, because blah.

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Guys can I have some help with question 6 pls. I have done part A but have no clue how to do the rest
ImageUploadedByStudent Room1421149973.424137.jpg1.2KB
anyone have the unofficial markscheme for may 2014 ocr chemistry b salters exam for chemistry for life- F331
In an equilibrium reaction why does the endothermic forward/backward reaction have a lower activation energy compared to the exothermic reaction?
Would anyone be interested in doing a level chemistry revision over skype?
Personally, I find it easier to revise if I have someone to discuss a problem with as if I explain my logic out loud to someone, they can point out where I'm going wrong and vice versa. If anyone would want a revision partner, or just someone to talk chemistry with, inbox me.

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