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OCR B Salters - F335 Exam - 15 June 2011

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Reply 600

brendan.

Original post by beckyxo

also what did people put for the one asking about why would farmers argue using that herbicide is ok?

I put...

The benefits of the herbicide outweigh the risks.

There could be more stringent measures involved to prevent the herbicide getting close to humans or other mammals.

Reply 601

Cyanohydrin

Original post by brendan.

http://www.chemguide.co.uk/inorganic/redox/oxidnstates.html
Near the bottom it says how one element can be oxidised and reduced in same reaction, so it's possible. :smile:

yeah good old disproportionation :biggrin:

so lucky I did it in my courswork

Reply 602

HK11

Original post by SmileyGurl13

Yeah that's what I did :biggrin:

I know someone has already asked it but it wasn't really answered what did you guys put for the ox and reduction qs I also put both sulphur as someone else did but this can't be right, can it :s-smilie:

I was going to put both sulphur because I thought it went from 0 to +4 and then also to -2. But for some reason it just didn't feel correct, although on reflection it probably was. I should get at least 2/4 though.

Reply 603

RobG93

Original post by ManPowa

The answer could only be phenyl amine, because it was representing the diazotisation reaction.

Yes, phenylamine is definitely correct..

Reply 604

Tetanus

Original post by brendan.

I put...

The benefits of the herbicide outweigh the risks.

There could be more stringent measures involved to prevent the herbicide getting close to humans or other mammals.

No other suitable alternative? :biggrin:

Reply 605

brendan.

Original post by SmileyGurl13

I'm so confused :s-smilie:

I still think it's 19!! xD

Me too!

Reply 606

Jake200493

Original post by Tetanus

Clever School, eh? :holmes:

Oh, no, we're all a bit thick to be honset xD Well, speaking for myself anyway, I don't want to offend them xD But we're also the only 4 people who passed AS. Out of 30 xD

Reply 607

Paolat

Original post by beckyxo

i got 19g for the last one too :s-smilie:

mega hated the oxidation/reduction question, way simple but got me so confused it went to -4 and -2 or just -4?? ahh :frown:

also that SF6 dot cross was sp annoying, took ages drawing it then realised id only drawn 5 F's so had to start again :frown:

also what did people put for the one asking about why would farmers argue using that herbicide is ok?

I said that it increases crop yeilds lol

Reply 608

tom108

Im really confused. Didnt reductiction also occur is fluroine? Went from -1 to -4 ????????????

Reply 609

zahre

Original post by brendan.

I put...

The benefits of the herbicide outweigh the risks.

There could be more stringent measures involved to prevent the herbicide getting close to humans or other mammals.

??[/QUO

Yeah i put that as one of my answers but completely made up the other point.

Reply 610

Kooper

Original post by Conor 419

Did well until the last question, I ran out of time. So many marks gone...****.

What's the general consensus, low or high grade boundaries?

I would have said high coming out of the exam since there were loads of 1 markers, but judging by the reaction here, maybe it'll be slightly below average. It wasn't a technically hard paper (apart from a couple of maths questions, but even they weren't unreasonable), but they might adjust the grade boundary depending on how people do. Personally, I still reckon no less than 83 for an A.

Reply 611

SmileyGurl13

Original post by Tetanus

No other suitable alternative? :biggrin:

Yeah I put:
1. No other herbicide could kill those plants
2. If it's easily so it doesn't get into contact with human/animals and doesn't get into our watersuply.

Meh I hate them questions. ¬¬

Reply 612

ManPowa

What would be the 6 marks for the colour question?

Reply 613

meerar20

Original post by cleverbong

I forgot to put +ve sign as well.
Is it +9979 Jk^(-1)mol^(-1) ?

Did you need to put the units? I didn't even notice that! ):

Also, don't suppose anyone has uploaded the paper/ has a link to it? (:

Reply 614

fozzy143

Original post by tom108

I did that, but i dont think its right :frown:

I used both forumula in the Data sheet. The RBr + CN- -->RCN and then RCN--H+/H20--> COOH. I mean they where both on the Data sheet so they cannot be wrong I think :P

Reply 615

francescaxxx

What did people put for SF4 going to SF6??

And whats the conjugate acid of H2PO4^-???

Also whats the bonding in Li at 298K???

Reply 616

meerar20

Original post by Kooper

Id-Id I think since one of them had no dipole.

I think it should have been permanent dipole - induced dipole?
But I only thought of that after the exam! ):

Reply 617

ManPowa

Original post by francescaxxx

What did people put for SF4 going to SF6??

And whats the conjugate acid of H2PO4^-???

Also whats the bonding in Li at 298K???

H3Po4

Metallic bonding.. Lithium is a metal right?
And what were the other two?

Reply 618

Flynn

Well that went badly. It was the hardest F335 paper I've seen, and it didn't help that I went on tilt as soon as my mind went blank on the diazonium salt question. Almost every question that seemed to come up in most past papers didn't come up and it seemed like a lot of the questions were there to trick you into not seeing what it was actually asking.

On the question where they gave the table with compounds and their entropies and melting points and it wanted to know what the bonds were. Was it intermolecular bonds or the actual bonds between the atoms. I guessed they wanted to know the actual bond types (ionic ect.),but is it me or was it not particularly clear what they wanted?

Its frustrating because I revised harder for this paper than any I've ever revised for, at the expense of every other subject, but I'll still probably end up doing better in C3 tomorrow. Well I guess I'll hope for low grade boundries, try to do well in F334 so I can scrape a B and then somehow get an A in physics so I still get the AAB that I need.

Reply 619

04ayasin

I think I did well. I see a lot of people saying they found it hard. Good luck to everyone. I attempted all the questions a few people i know ran out of time. some people didn't learn the reactions so they got stuck on them.

I didnt get the question where you had to ring the bit on the molecule that went into the plant cell or something. Ringed the benzene ring. I also didn't get the oxidation state for sulfur, so I guessed that as well can't remember what I put.
For the hexaflouride question I guessed the following:
2SF4 + O2 --> SF6 + SO2 + F2
What did others put?