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OCR Chemistry F322 June 2016

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What did you guys get for the c-o enthalpy? I did 1056/3 because there were three moles of H2 and I thought 1056 would be too big :/
Original post by NiniMCa
What did you guys get for the c-o enthalpy? I did 1056/3 because there were three moles of H2 and I thought 1056 would be too big :/


I think I put 1056
Original post by mercuryman
image.jpg Guys does this confirm that nitrogen dioxide can also be a source of NO oxides? Like it is technically right? Right? I Identified thunderstorms and no2 hopefully I don't lose yet another mark :frown:


NO2 itself IS a nitrogen oxide, so I doubt it'll be a mark. Sorry man
Original post by mattyk5
I got 14.0 for the mass, what did anyone else get?


That's exactly what i got
Original post by NiniMCa
What did you guys get for the c-o enthalpy? I did 1056/3 because there were three moles of H2 and I thought 1056 would be too big :/


There was only 1 mol of CO bonds, so I don't think dividing by three was correct (the actually average bond enthalpy is around 1056 KJmol^-1(1077) :/)
Reply 125
Avatar for Freyk2
Freyk2
2
I got 14.1 for the mass and 1062 for CO bond enthalpy
14655761773841084053885.jpganyone else also recognise these answers?
What were reagents and conditions on first page?
Original post by ali_t9001
NO2 itself IS a nitrogen oxide, so I doubt it'll be a mark. Sorry man



Ah you're right but n20 can form NO aswell which may be a mark, which is what I meant in my head but obvs I didn't put it down
Original post by mercuryman
What was the mass of excess magnesium ?

I got 0.302 something like that

25% + mass of magnesium no?


But my mates said it was 25% + mass of the other metal which gave the mass of excess magnesium


I got 0.38. 0.302 was the moles used, you needed to add 25%. So moles x 1.25
Reply 130
Avatar for Freyk2
Freyk2
2
But if it was as ester of F and G shouldn't the carboxylic acid be attached the alcohol that was propan-2-ol?
Original post by BrownGuyIrfan
Yeah...exactly that except i put the OH group below instead of above the carbon but it's basically the same thing.
Original post by nicoleemmak
What did everyone write for the one about adding acid and alkali to shift the equilibrium??


Well, when acid added, H+ conc increases so sift right to decrease it, thus went orange. When Alkali added, reacts with H+ and makes H20, so both factors mean sift left so orange
Original post by hollygc123
Did anyone get something like 0.38 for the mass of mg? because m=0.0125x24.3 =0.303. And then you multiply that by 1.25 to add the 25% which gave 0.379 so 0.38 to 2dp??


I got that
Original post by President J
I got 0.38. 0.302 was the moles used, you needed to add 25%. So moles x 1.25


Hmm I did it another away

(0.0125 x 24.3 ) x 1.25

Giving me 0.380g
Original post by jadder1224
14655761773841084053885.jpganyone else also recognise these answers?


Yep! the box at the top are the equations showing how NO catalyses the breakdown on O3, and the structures are the fragment ions I and II from the Mass Spec diagram, both of which i got as well :biggrin: (hopefully we're both right)
Original post by mercuryman
Hmm I did it another away

(0.0125 x 24.3 ) x 1.25

Giving me 0.380g


Sorry, that's what I meant.
Original post by hollygc123
Did anyone get something like 0.38 for the mass of mg? because m=0.0125x24.3 =0.303. And then you multiply that by 1.25 to add the 25% which gave 0.379 so 0.38 to 2dp??


Yep, that's definitely the right answer :smile:
What did everyone get for the litres question?
Reply 138
Avatar for xhxhxh
xhxhxh
2
Original post by President J
I got 0.38. 0.302 was the moles used, you needed to add 25%. So moles x 1.25


i got 0.38 too!
Original post by FluffyCommie
There was only 1 mol of CO bonds, so I don't think dividing by three was correct (the actually average bond enthalpy is around 1056 KJmol^-1(1077) :/)


Thanks :smile: I feel like I thought too much about the questions and didn't finish all of them :'( anyone remember how many marks each question was worth?

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