ocr a f325 revision thread

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dS was negative, so -TdS was positive; that was the point of why it is never feasible.

the guy above who did the equation between sn and io3- thing he put OH- as product it should be h2o if i remember correctly

Reply 4281

scorpio22

i think i lost 27 marks,
very very sloppy, hopefully i just made a safe high B or very very low A.

Reply 4282

Benjy100

Anyone think they'll allow

6H⁺ + 5Sn²⁺+2IO3- -------> 5Sn⁴⁺ + 2I₂ + 6OH-

Or have I assumed alkaline conditions? (absolutely no idea why I didn't just go for water, the safe option haha)

(edited 10 years ago)

Reply 4283

RnTf

Original post by scorpio22

i think i lost 27 marks,
very very sloppy, hopefully i just made a safe high B or very very low A.

that should be an A

Reply 4284

Funtry

Original post by Kat12395

WE HAVE FINISHED THE MARK SCHEME (Finally!)
https://docs.google.com/document/d/1WICd6ufVwBxfVz10_b4Hqd85oSv2FMQTrcll_t5qD0k/edit?usp=sharing
YOU'RE WELCOME!

Thanks! For the Chlorine question I put that the addition of OH- may react with the H+ ions to form water, and then this water will react with the Cl2 to form ClO- :smile:

Reply 4285

fayled

Original post by Benjy100

Anyone think they'll allow

6H⁺ + 5Sn²⁺+2IO3- -------> 5Sn⁴⁺ + 2I₂ + 6OH-

Or have I assumed alkaline conditions? (absolutely no idea why I didn't just go for water, the safe option haha)

Can't see why not, everything balances and charge is balanced so...

Reply 4286

wakaas

For the optical isonerisim i put both isomers but i didnt put brakets the charge and the line in the middle how many marks out of three will i get?

Reply 4287

Benjy100

Original post by wakaas

For the optical isonerisim i put both isomers but i didnt put brakets the charge and the line in the middle how many marks out of three will i get?

I think the brackets and the charge are necessary (or at least the charge). I doubt the line in the middle matters. Probably 1-2 marks

(edited 10 years ago)

Reply 4288

MathsNerd1

Original post by Funtry

Thanks! For the Chlorine question I put that the addition of OH- may react with the H+ ions to form water, and then this water will react with the Cl2 to form ClO- :smile:

Just out of curiosity how many marks do you think you got today from the MS?

Reply 4289

needtosucceed=)

Original post by wakaas

For the optical isonerisim i put both isomers but i didnt put brakets the charge and the line in the middle how many marks out of three will i get?

you'll probably get 2

Reply 4290

canabel

Original post by Kat12395

WE HAVE FINISHED THE MARK SCHEME (Finally!)
https://docs.google.com/document/d/1WICd6ufVwBxfVz10_b4Hqd85oSv2FMQTrcll_t5qD0k/edit?usp=sharing
YOU'RE WELCOME!

thx for the ms, i felt slight less panic right now, but still ....

=]

Reply 4291

Choco_Pig

Original post by Kat12395

WE HAVE FINISHED THE MARK SCHEME (Finally!)
https://docs.google.com/document/d/1WICd6ufVwBxfVz10_b4Hqd85oSv2FMQTrcll_t5qD0k/edit?usp=sharing
YOU'RE WELCOME!

Thank you thank you thank you for posting this!! Made my night a hell of a lot better!!! Thought I failed, but now I'm happy :smile:

so thanks again! :biggrin:

Reply 4292

MathsNerd1

Original post by Benjy100

I think the brackets and the charge are necessary (or at least the charge). I doubt the line in the middle matters. Probably 1-2 marks

Isn't it the line in the middle which represents a mirror that implies that they are optical isomers? I'm quite sure its necessary.

Reply 4293

needtosucceed=)

Original post by Kat12395

Question: If I put O- at the ends instead of OH will I get a mark?:L

Original post by PythianLegume

O- is the correct version of the ligand, so you will get the marks :tongue:

omg really? I put o- as well but I thought it was wrong, everyone was saying there should be hydrogens on the end or something

Reply 4294

scorpio22

Original post by RnTf

that should be an A

I'll take a B... i so messed up my biology but im slowly reedeming myself with chemistry...

role of f324 :unimpressed:

Reply 4295

1901

What do everyone's teachers think about the coursework grade boundaries? Mine seem to think they might be sligghhhtly lower than last year's ones as the papers were a bit harder in their opinion.

Reply 4296

Benjy100

Original post by MathsNerd1

Isn't it the line in the middle which represents a mirror that implies that they are optical isomers? I'm quite sure its necessary.

Well it mean it just wants you to draw the isomers, which are separated by brackets and a quite clearly reflections of eachother anyway. In order to back up my bold claims I shall cite page 213 of the text book :P

Reply 4297

emah123

So going by the mark scheme I think I got 61/100. I'm so screwed- will definitely not meet my offer for medschool :frown:

I worked the hardest for this paper but ocr just have to screw you over don't they?!

Reply 4298

Benjy100

Original post by needtosucceed=)

omg really? I put o- as well but I thought it was wrong, everyone was saying there should be hydrogens on the end or something

which question are you talking about here?

Reply 4299

MathsNerd1

Original post by Benjy100

Oh okay, yeah that's fair enough I just thought it was always needed but what you've said is correct so they should be perfectly fine if they forgot it, I always go for a worse case scenario so I can be pleasantly pleased on results day, at least I hope it to go that way :tongue: