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ocr a f325 revision thread

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Original post by Jblake
Mass of CO2 absorbed by plants each year via photosynthesis (2 Marks)

Total Energy / Enthalpy Change = X moles

X*6*44 = CO2 in grams :smile:


do you get the moles by doing the energy of the co2 / x = deta H value

x being the unknown moles?
Original post by otrivine
for the equation between ethanoic acid and Al I REMEMBER putting a 1/2 for H2 at the end?

Someone else asked me about that- as long as it's a multiple; you're fine!
Original post by chocandy21
For the structure of the mad bidentate ligand did anyone notice on end there was an O-H whereas on the other end it was oxygen with a dashed line then hydrogen? Does that mean the hydrogen was on the other ligand?


YES! I thought that, I did on one side O-H and on the other just O-

Hope that's what you meant?

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Original post by Raj Kang
Am I right in thinking that the the structure molecule, 2 h's attached at the nitrogen group is wrong?

The H's attached to the OH? Yeah, I just wrote O- too...
Original post by otrivine
for the equation between ethanoic acid and Al I REMEMBER putting a 1/2 for H2 at the end?


I think thats what I did, as long as everything is balanced, having multiples is fine I think

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Anyone wanna give me rep for making the mark scheme?;D I think I deserve it for my efforts, making it after being in exam conditions for five hours!
33681795.jpg
Original post by itshollaaay
YES! I thought that, I did on one side O-H and on the other just O-

Hope that's what you meant?

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yes me too :biggrin:
Original post by IAMSODAMNFINE
I think that's a little too low..
I reckon:
FULL: 92
A*: 85
A:74
B: 65
C: 59
D:53
E: 47


The difference between each grade is usually constant.... that was just using Jan13 boundaries as an example anyway, not a prediction for ours :P
Original post by Kat12395
The H's attached to the OH? Yeah, I just wrote O- too...


I only noticed at the very last minute there was a dotted line meaning it was a hydrogen bond so there had to be another hydrogen present on the other oxygen, was quite close really :tongue:
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emah123
OP
5
can i possibly get 105 ums by dropping 35-36 marks in this paper? or is there no chance?

FEELING SO DEPRESSED RIGHT NOW.
Reply 4330
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drplease
Can you say oxidising agent is iodine? because that is technically reduced from +5 to 0
okay for the last question

1) I got the correct 7H2O

thing then i did mole ratios between Ni2+ and the product,

i did some sort of mole ratio, how many marks out of 7?
Original post by emah123
can i possibly get 105 ums by dropping 35-36 marks in this paper? or is there no chance?

FEELING SO DEPRESSED RIGHT NOW.


I am in exactly the same situation. The amount of past papers I have done and have got more than enough to get 105ums but this paper I have easily dropped 35 marks :/


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Original post by MathsNerd1
I only noticed at the very last minute there was a dotted line meaning it was a hydrogen bond so there had to be another hydrogen present on the other oxygen, was quite close really :tongue:

See I THINK it may have been O- on one and OH on the other, thinking about it... But I had half an hour to do the photosynth question onwards- so it was a pretty good attempt!;D I might get one mark!:L
Reply 4334
Avatar for emah123
emah123
OP
5
can i possibly get 105 ums by dropping 35-36 marks in this paper? or is there no chance?

FEELING SO DEPRESSED RIGHT NOW.
Original post by emah123
can i possibly get 105 ums by dropping 35-36 marks in this paper? or is there no chance?

FEELING SO DEPRESSED RIGHT NOW.


perhaps, yes. I'm sure you have done bettwe than you thought, you may get more marks from the allow section. :smile:
Original post by Kat12395
Depends on the grade boundaries. It'll be damn close that's for sure!


Tell me about it, typical that this exam I didn't finish it and I was panicking about the time issue so my mind was else where!
I really hope grade boundaries are low, very low! Otherwise I may as well sell myself for money if I don't get my A to get into uni hahaha

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Original post by drplease
Can you say oxidising agent is iodine? because that is technically reduced from +5 to 0


Thats what I thought?! Isnt it more reduced than IO3 (or whatever it was)

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Original post by itshollaaay
I am in exactly the same situation. The amount of past papers I have done and have got more than enough to get 105ums but this paper I have easily dropped 35 marks :/

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I'm in the same boat and we're not the only ones! Have hope- the grade boundaries may well drop! In Jan they were 63 for 105 (you could drop 37) and this paper's consensus is generally more difficult! Have faith- not all is lost!
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JimmyA*
5
Original post by Kat12395
See I THINK it may have been O- on one and OH on the other, thinking about it... But I had half an hour to do the photosynth question onwards- so it was a pretty good attempt!;D I might get one mark!:L

I think it was a H on both as it asked for the structure before it had reacted with NH3 which took the H+ off to form the ligand.

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