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# OCR Chemistry F322~ 4th June 2013~ AS Chemistry watch

• View Poll Results: How did you find the exam
Hard A= 72
42
15.22%
It was okay A= 76
99
35.87%
Easy A= 79
75
27.17%
Very Easy A=82
60
21.74%

1. (Original post by nivvy21)
Someone help me with this question please! Thanks and much appreciated, in advance!
If this makes sense to you, great!
Attached Images

2. here you are!
Attached Images
3. F322-01Jan13.pdf (275.1 KB, 60 views)
4. F322_MS_Jan13.pdf (761.3 KB, 56 views)
5. This is the answer to the +82 question
Attached Images

6. (Original post by sid101)
here you are!
thaank youuu:d
7. Would be funny if you got a table with all the reactions and it asked for the specific temperature and pressure, lel

[12 marks]
8. (Original post by Joey952)
bump
For part a?

a) You need to use the vol/24 = moles formula from F321 to calculate the moles of hydrogen. It then gives you the energy released for 3 moles of hydrogen so divide your answer by three and times that by the energy released which will give you your answer.

Need help with anything else just ask!
9. (Original post by nivvy21)
Someone help me with this question please! Thanks and much appreciated, in advance!
I think the most obvious method of doing this is to calculate both ppm's into percentages and them calculate the difference.
So 380ppm to % is 380/1000000 x 100 = 0.038%
And 300ppm to % is 300/1000000 x 100 = 0.030%
So the difference is 0.038 - 0.030 = 0.0008

This is the same as (380-300)/1000000 x 100 so either way works.

EDIT: I may be wrong though, looking at how they word the question, I'm not sure if it means as an increase of percentage from the first value or an increase in general. Mine being an answer for an increase in general. Your's being a value for the increase in the last value.
So your answer comes out at 26.67% (increase from the previous value) which makes sense as well.
10. Oh god nearly 3 hours into the exam!!

I am revising now... haven't done TOO many past papers... just from 09-13
11. (Original post by GeneralOJB)
Would be funny if you got a table with all the reactions and it asked for the specific temperature and pressure, lel

[12 marks]
That would be great tbh
13. (Original post by CRW1996)
Maybe I'm just being stupid but I don't understand the answer to 4 e) ii) on the may 2012 paper. Could anyone explain it to me please? anyone?
I have the exact same problem, tried to do this last night and didn't have a clue, please let me know if you find out! thanks
14. Hi everyone,

Best of luck today!
15. (Original post by CT1995)
I have the exact same problem, tried to do this last night and didn't have a clue, please let me know if you find out! thanks
Whats the problem with the question?
Its this one right:
Methane acts as a greenhouse gas because it can absorb infrared radiation.
Explain how increased blah blah blah...? (2 marks)
16. (Original post by CT1995)
I have the exact same problem, tried to do this last night and didn't have a clue, please let me know if you find out! thanks
I may be able to help out here.
You want to make N20
so you see the first equation, you're going to need to take the reverse enthalpy of this (ie if you read it from right to left you get to N20) also then you notice that the CO and the C cancel out with the bottom equation so you're then left with the equation given in the question - don't know if I'm making sense.
So you want to take
+193-111 which will give you the right answer.

If you get a question like this in the exam today I wouldn't panic - it's only worth two marks anyway

Is this the question you're referring to?
17. Im in year 12, an di got a U in the mock, perhaps someone can help me, whats a hydrocarbon, ive got so much revision to do for this exam
18. (Original post by CT1995)
I have the exact same problem, tried to do this last night and didn't have a clue, please let me know if you find out! thanks
The way I think about it is if you put the equations under one another and cancel out the common molecules which leaves you with:
NO2 -> N2
1/2 O2

Formation is Products - Reactants
-193 - (-111) = +82

It requires light assumptions and guessing, but slightly makes sense in a dream world

EDIT: PAAHA, it gives -82 not +82. Yeh I don't get it either
19. (Original post by Zzzyax)
Im in year 12, an di got a U in the mock, perhaps someone can help me, whats a hydrocarbon, ive got so much revision to do for this exam
a compound that contains a carbon and hydrogen only
20. (Original post by Zzzyax)
Im in year 12, an di got a U in the mock, perhaps someone can help me, whats a hydrocarbon, ive got so much revision to do for this exam
A compound of hydrogen and carbon only
21. (Original post by hopefulmedic28)
I may be able to help out here.
You want to make N20
so you see the first equation, you're going to need to take the reverse enthalpy of this (ie if you read it from right to left you get to N20) also then you notice that the CO and the C cancel out with the bottom equation so you're then left with the equation given in the question - don't know if I'm making sense.
So you want to take
+193-111 which will give you the right answer.

If you get a question like this in the exam today I wouldn't panic - it's only worth two marks anyway

Is this the question you're referring to?
Actually makes sense thank you.
22. (Original post by Zzzyax)
Im in year 12, an di got a U in the mock, perhaps someone can help me, whats a hydrocarbon, ive got so much revision to do for this exam
I think you may have started a bit late... It's compound consisting of only hydrogen and carbon atoms

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