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OCR Chemistry A - Chains, Energy and Resources (F322). POST EXAM DISCUSSION.

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Reply 380

Freerider101

ViralRiver

They will never ask about major and minor compounds, you just need to know that two different products can be formed.

Thats luckly then. That was something else I wasn't 100% sure on.

Reply 381

ViralRiver

At least that's what it says in the OCR book. It just says to research the guy's name if you want to know more (and doesn't say anything about the greater atomic mass or whatever you said). So, unless the OCR book is wrong, it won't come up.

Reply 382

CHILLIN-DRAGON

ghostkillah

I just did the Jan 2010 paper. Fairly difficult - stuff on there like Kyoto protocol for the answers but on the spec OCR says it cant be examined?. 79/100 so hopefully that was an A. Need to sort out esters - especially drawing them. eg: c6h10o4 - the formula is crazy. Can someone help me out with drawing esters??

ye i dont understand that because they say any change to the spec would have a black line and the kyoto protocol doesn't, when it says not examinable does that mean you can use it in an answer but they wont ask you about it?
please can someone confirm this alot of people have been asking this :frown:

Reply 383

CHILLIN-DRAGON

there are two cycles if they ask it for combustion, they would give you a table with the combustion values for each compound.

if its for the formation cycle they will give you the values from a table containing the formation values of the compounds.
:yep:

Reply 384

ViralRiver

How do you draw esters? o0

Reply 385

LazyWorseThanInfidel

http://www.knockhardy.org.uk/sci.htm

Reply 386

ViralRiver

Ok, I tried doing the structural formula for esterification between propanoic acid and butanol to make butyl propanoate. Can anyone tell me whether this is right?

CH_3CH_2COOH+CH_3(CH_2)_2CH(OH)\rightarrow CH_3CH_2CO(CH_2)_3CH_3+H_2O

Thanks.

Reply 387

jontylol

94/100 on june 09 :biggrin:

Most marks lost on the green chemistry questions... Must revise those later on....

Reply 388

benweil

97/100 on the specimen paper. :smile:

I am an idiot though, and misread the last question so forgot to talk about hydration of but-1-ene. Eurgh. Lost me two marks

Reply 389

LazyWorseThanInfidel

ViralRiver

Ok, I tried doing the structural formula for esterification between propanoic acid and butanol to make butyl propanoate. Can anyone tell me whether this is right?

Thanks.

an ester is a carbon with 2 oxygens on it. one of those oxygens will have a double bond. there is only one oxygen in your product so it must be wrong.

this is methylethanoate

CH3OCOCH3

notice how the oxygens are next to the carbon

Reply 390

CHILLIN-DRAGON

i think i found another mistake in the heinamann text book can someone confirm this

page 143 question 11

look at the answer by have they used c2h5 in the termination step when its butane reacting with bromine :s

Reply 391

JuanSheet

Good news, exams tomorrow and I'm averaging 96% on F322( and 100% on the two papers on this thread) lets just hope they don't put in to many ambiguous questions :frown:

Reply 392

Pedus

ffs im feeling sleepy even after having a little nap and nothings going in :banghead:

Reply 393

ViralRiver

LazyWorseThanInfidel

I misread my diagram >< . Is this the product?

CH_3CH_2COO(CH_2)_3CH_3

Reply 394

J00100

Can someone please help me?
I've just done the specimen paper and for question 6(b)(i) where it asks for a balanced equation for the complete combustion of heptane i got:
C7H16 + 11o2 -> 7CO2 + 8H2O
but the answer says 11.5 O2.
And i don't understand the answer for the polymer of but-2-ene (showing 2 repeat units) either on question 7?
i got..
.............CH3.....CH3......CH3......CH3
.............|........|..........|.........|
......... -- C --- C ------ C ----- C --
............ |........|.........|.........|
............ H........H.........H.........H

Is this right because the mark scheme says it isn't :frown:

Please help :smile:

Reply 395

intellectual1

Pedus

ffs im feeling sleepy even after having a little nap and nothings going in :banghead:

I thought you did every paper and was prepared :confused:

Reply 396

CHILLIN-DRAGON

Pedus

ffs im feeling sleepy even after having a little nap and nothings going in :banghead:

same here and it feels like ive forgotten all the green chem stuff :s

i feel like times running out now, im gonna try to revise till 11 hopefully then go to sleep.

btw does anyone know if we have to learn any apparatuses for reflux, or for Q=mct, because they are in the text book and even the revision guide and i haven't learnt them :frown:

Reply 397

LazyWorseThanInfidel

ViralRiver