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# Equilibria, Energetics and Elements (F325) - June 2011 Exam. watch

1. (Original post by Student21)
You have to understand the amount of pressure and frustation we were feeling in the exam so these guys were probably concentrating 100% on the exam and had no notice of the time limit until it was too late.
Thanks
2. Delta g is decreased as temperature increases only if delta S is a positive number. Delta S was negative wasn't it? Therefore, delta g would increase as temperature increased.
3. OCR can suck MY magic tang.
4. Anyone got an idea of how many people may have taken the exam nationally? Just curious as the number on the facebook page is creeping closer to 1000
5. (Original post by jam.wa)
OCR can suck MY magic tang.
Important question! Did anyone else think that Magic Tang sounds like a porn name? I mean, seriously. Tang.
6. (Original post by LauraBritton)
I only found out through a friend...we were all so stressed out, working out the timings wasn't the first thing on our minds

8. (Original post by CoventryCity)
75% reacted so 0.6 moles of NO using the molar ratios that mean 0.3 moles of the other reactant reacted. 0.6 moles of product formed as the ratio was 22
This means the equilibrium moles of each were 0.2, 0.4 and 0.6. Divide by 2dm3 for concentration and sub in to Kc
You still dont get anything above 5, kc of products are found out by the moles which have reacted and the equation was 2N0 + o2 = 2No2
Moles start 0.80
Moles reacted 0.20
Moles equib 0.60 0.20
Just an example not the real thing.
9. (Original post by science7)
LOL I wish! I have 4 more exams!

But I remember now. I got Delta G as -108 and the reaction was feasible.
i have -108 too!
10. OCR just can't get it right.

Did anyone do the Biology paper on monday??
11. Can someone post the link for the FB group against this exam?
Thanks
12. (Original post by woods.vanessa)
Can someone post the link for the FB group against this exam?
Thanks
thats what i want aswell, plz someone post it
13. Aw, I want to see this paper, and see how well my year group would do.
It sounds horrible.
14. (Original post by vinit92)
You still dont get anything above 5, kc of products are found out by the moles which have reacted and the equation was 2N0 + o2 = 2No2
Moles start 0.80
Moles reacted 0.20
Moles equib 0.60 0.20
Just an example not the real thing.
mate, 0.8 moles of NO to start with, and 0.7moles of O2.
0.8x0.75 = 0.6 reacted, so equilibrium amount is 0.2
2:1 so 0.3 reacted of O2, so thats 0.4 at equilibrium, meaning theres 0.6 moles of product.

divide them all by 2 to get concentrations
0.3^2/0.2x0.1^2 = 45. you can check it as many times as you like, it will always be 45.
15. [QUOTE=vinit92;32205048]You still dont get anything above 5, kc of products are found out by the moles which have reacted and the equation was 2N0 + o2 = 2No2
Moles start 0.80
mole of NO at equlibrium=0.25x0.80=0.2mole
mole of O2 at eq=0.7-(0.6/2)=0.4 mole
mole of NO2=0.6mole

volume of 2dm^3

therefore con was 0.1M NO,0.2M O2, 0.3M NO2.

Kc=(NO2)^2
----------- = 45dm3mol^-1
(NO)^2(O2)
16. "Comment on the validity of this claim" for Magic Tang. What did people write?

I said that the pH was low and would impart an acidic taste on the tongue, hence the claim was correct
17. (Original post by vinit92)
You still dont get anything above 5, kc of products are found out by the moles which have reacted and the equation was 2N0 + o2 = 2No2
Moles start 0.80
Moles reacted 0.20
Moles equib 0.60 0.20
Just an example not the real thing.
So for my Kc I had [0.3]^2 / ( [0.1]^2 x [0.2] )
when I tapped that in I got 45

Kc is calculated by using the concentrations of what is present in the equilibrium mixture, not the moles that have reacted.

Check pg 129 heieneman text book
18. (Original post by wilsea05)
mate, 0.8 moles of NO to start with, and 0.7moles of O2.
0.8x0.75 = 0.6 reacted, so equilibrium amount is 0.2
2:1 so 0.3 reacted of O2, so thats 0.4 at equilibrium, meaning theres 0.6 moles of product.

divide them all by 2 to get concentrations
0.3^2/0.2x0.1^2 = 45. you can check it as many times as you like, it will always be 45.
phewww I got the same moles as you. Hope thats right.
Don't know what I got at the end though?
19. I'm just waiting to see the mark scheme comments

ans: 88.4 ----- e.c.f just allow any numerical number

ans: correct diagram with bond angles ----- e.c.f allow any diagrammatic image, even those consisting of male genetalia with a note of 'Suck my **** OCR' written above

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