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# A2 OCR Chemistry B F334 - June 2015 watch

1. (Original post by strugglingstdnt)
what ums do we need for an A out of 600?
480/600 for an A
2. (Original post by strugglingstdnt)
what ums do we need for an A out of 600?
480 for an A.
3. I got 1.26V too. It was the more positive SEP - the more negative SEP. 1.00V-(-0.26V) = 1.26V
4. (Original post by harry4625)
another awful question. You had to convert the time into rate by dividing by 1. then when you compared the increases it was clearly 1st order. another horrible way of making a question more difficult than it needed to be by OCR
I think you've over complicated it, it's just that it had a constant half life of something like 120 hours i think which shows its first order
5. (Original post by strugglingstdnt)
what ums do we need for an A out of 600?
480 (80%)
6. (Original post by TikiLodge)
I just put C=ON-H.
OK, thank you. That's what I did too. its realy hard sometimes to know what to put as I always doubt my answer when it looks wired like that :P

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7. 100% need to retake this exam next year, what was the answer to the IR
spectrometry?
8. right do you guys reckon this answers OK for the DNA thingummy....
CG = 3 hydrogen bonds (pyrimidine)
AT = 2 hydrogen bonds (purine)
Hydrogen bonds break between bases and two strands of DNA are reformed using DNA polymerase via semi-conservative replication

Btw why were we doing the ocr biology exam today, I swear that we were meant to have f334 CHEMISTRY exam today..... :/
I think you've over complicated it, it's just that it had a constant half life of something like 120 hours i think which shows its first order
But it said to use the data, no indication of half life there.
So I realised that there was a difference of 70 hours between 30 and 100, then 220 and 290. I calculated the ratio between the concentrations for both times and I got 0.77 for both of them, so it was first order.
10. (Original post by thedontom)
That DNA question was do-able but the different amounts of hydrogen bonding was just there to give the biologists a hand..
I knew the number of hydrogen bonds because of biology, but you could figure it out from the diagrams of the bases because C and G have 3 OH groups to form hydrogen bonds with, A and T only have two...
11. i worked out that i need 96-106 in f335 for an A to be secured if i am still going to uni
12. (Original post by TheRAG)
But it said to use the data, no indication of half life there.
So I realised that there was a difference of 70 hours between 30 and 100, then 220 and 290. I calculated the ratio between the concentrations for both times and I got 0.77 for both of them, so it was first order.
It was using the data because you could show between certain time values the concentration had halved and it was the same time taken for the concentration to half again. There was indication of the half life in the data because you could work out how long it took for the concentration to half and that is half life...
i worked out that i need 96-106 in f335 for an A to be secured if i am still going to uni
same man, its a piss take
14. Whose got OCR b physics g494 tomorrow. That'll be fun!!!
15. (Original post by BFP=big fat poo)
right do you guys reckon this answers OK for the DNA thingummy....
CG = 3 hydrogen bonds (pyrimidine)
AT = 2 hydrogen bonds (purine)
Hydrogen bonds break between bases and two strands of DNA are reformed using DNA polymerase via semi-conservative replication

Btw why were we doing the ocr biology exam today, I swear that we were meant to have f334 CHEMISTRY exam today..... :/
I was stupid and crossed out the no. of hydrogen bonds do you think ill get a mark for saying CG has more hydrogen bonds? I put all the other stuff you said
16. (Original post by BrandonRendell)
Hydrolysing that big polymer with the arene groups should have gotten you one with NH3+ and the other with a carboxyl group and the OH untouched,

Percentage by mass question I got 97.1%

The choking gas I wrote ethanoic acid

The toxic gas from the steel recycling bit i wrote chlorine gas

The thing that reacts with iodine was the one under it in the table

TLC question was nice

the biology DNA replication was nice, my teacher used some retarded way of remembering that guanine and cytosine form three H bonds so that made me smile when it came up

Drawing two amino acids reacting together is a godsend OCR y u give free marks thanks very much, aswell as the enzyme v ph graph <3

I just thought the paper was the nicest they've given in a long time. Think about it, no long ass question about rates, multi step reactions etc, no strange curveball mole calculation

I reckon the only things I know I got wrong was the IR spectra, and the two 1 markers about combinational chemistry and improving medicines
**** i forgot the + on the NH3 in the resultant compound for the hydrolysis bit, I couldn't decide between NH2 and NH3
17. (Original post by Marseille013)
In the Electrochemical cells diagram, all ions were in solution right? with 2 platinum electrode
I put this
18. honestly that exam was the worst thing ever I did last year's paper last night and I got 88/90 and I'm not even sure if I've even scrapped an A in that paper

Why are OCR trying to mess with our lives
19. (Original post by Mars256)
Whose got OCR b physics g494 tomorrow. That'll be fun!!!
Me i dont see any point in doing past papers i am going to do hard questions that i can find on mechanics in my maths book and online thermal questions
20. (Original post by Jaz_ace)
same man, its a piss take
They are pricks tbh i don't even do biology i couldn't do that well in that question if i wanted to.

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