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STAR976
are there any revision noted for this on tsr? i only started revising today and im worried!!!!!! how hard do u htink it will be? have the year below done the first unit exam yet@;...does anyone know when it is?


You just started revising for this exam which is tomorrow? Good luck!
No the year 12's are doing the first unit tomorrow aswell. Both are on the same day.
Well, for me last years was hard, seeing as a I got a D. I don't know what the grade boundaries for last years was and no one can say whether it is going to be easier or harder this time round, although I would love for it to be easy.
tcdc09
Addition reactions that only make one product have 100% atom economy because they are the only product made so every atom is used. Subsituition reactions have two products, which means it cannot have an atom economy of 100% because you are making an unwanted product too

Does that make sense or did i explain it really poorely?

ohhhh thanks! yeah i understand now. :biggrin::biggrin::biggrin:

Another Q: how can you have a high % yield and low atom economy?
STAR976
are there any revision noted for this on tsr? i only started revising today and im worried!!!!!! how hard do u htink it will be? have the year below done the first unit exam yet@;...does anyone know when it is?

haha I'm starting today too... i always seem to do this. Really got to break this habit. <<procrastinator>>

and don't worry, I realised that there's actually very little to memorise. Most of it is just understanding the concept. Just do some past papers after reading your notes/textbook. :smile:
Reply 43
I Have No Imagination
You just started revising for this exam which is tomorrow? Good luck!
No the year 12's are doing the first unit tomorrow aswell. Both are on the same day.
Well, for me last years was hard, seeing as a I got a D. I don't know what the grade boundaries for last years was and no one can say whether it is going to be easier or harder this time round, although I would love for it to be easy.



i got an A time im just resitting for a higher one...i just ceebed before so ill do a bit of cramming. yeah i've done about 2 hours now, probs do another 2 later and then like 2 more tomorrow moring?
Reply 44
Original post by &#37011
ohhhh thanks! yeah i understand now. :biggrin::biggrin::biggrin:

Another Q: how can you have a high % yield and low atom economy?


It is like % yield is how much you obtained compared to how mcuh you started with whilst atom economy is about how you used the atoms - i think but i would double check with a textbook lol
Reply 45
Original post by &#37011
ohhhh thanks! yeah i understand now. :biggrin::biggrin::biggrin:

Another Q: how can you have a high % yield and low atom economy?



You can have a reaction which gives a good yield of the desired product but also has lots of useless by-products
STAR976
You can have a reaction which gives a good yield of the desired product but also has lots of useless by-products

ohhh ok ok cheers. :biggrin:

Sorry... i got another Q (hahaha :o:): how do you process waste polymers? it's a bit confusing in the textbook.. :confused:
STAR976
You can have a reaction which gives a good yield of the desired product but also has lots of useless by-products

ohhh ok ok cheers. :biggrin:

Sorry... i got another Q (hahaha :o:): how do you process waste polymers? it's a bit confusing in the textbook.. :confused:
Reply 48
Original post by &#37011
ohhh ok ok cheers. :biggrin:

Sorry... i got another Q (hahaha :o:): how do you process waste polymers? it's a bit confusing in the textbook.. :confused:


you can sort them into different types and then recycle them
you can combust them and use teh released energy in another process

hope this helps.
Reply 49
What could be the long essay type questions be on?

for june 2009 the two were about E/Z isomerism and infra red spec
Reply 50
????
STAR976
you can sort them into different types and then recycle them
you can combust them and use teh released energy in another process

hope this helps.

oh ok. So no more detail is needed? cos the textbook goes into so much detail, I wasn't sure if it was necessary. okay thanks.
Reply 52
.......so......
Reply 53
:yawn:
Do any of you have a special way of remembering the effect of a change in temp, conc, and pressure on the equilibrium... i'm finding it so hard to memorise. T_T
Reply 55
thanks.....
Reply 56
so guys what do you think they will ask about extract treating the public water supply
Reply 57
btw is this ocr salters or just ocr?
Reply 58
OCR Chemistry A...not salters
Reply 59
man i just realised what the time is...i need to revise mehnsss!!!! i started at around 6 and stopped about an hour and a half later...ah well, i've done chaps 1 and 2....i mihgt do 3 and just leave 4, its more or less common sense anyway and 3's easy! x are u guys all ready?

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