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

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Reply 2180

Unkempt_One

Original post by susan23

gradiet at what point?

The tangent you use to figure out the initial rate, ie.(0,0.010)

Reply 2181

tessfoley

Say you only worked out 2 half lives as 190 & 210 so said it was second order and wrote all the rest correct and folled through. With ECF how many marks do you think you would lose?

Reply 2182

VetApplicant2011

Original post by pavan pong

it didnt say it was endothermic did it? it said it took place at zero so must it be exo as it requires no energy

No but the process of going from a solid to a liquid means breaking bonds, which is endothermic, and if you think about the process in itself you have to put energy in in order to make something melt.. 0 degrees is just an arbitrary value we have created, its actually 273 Kelvin..

Reply 2183

pavan pong

Original post by tessfoley

Say you only worked out 2 half lives as 190 & 210 so said it was second order and wrote all the rest correct and folled through. With ECF how many marks do you think you would lose?

i think 2 or 3

Reply 2184

Unkempt_One

Original post by Sereni

Using lactic acid and its salt my ratio was 2.04:1

1/2.04=0.49 so that's what I got.

Reply 2185

Lissa-154

Got so much wrong in this paper by the looks of things :/ don't think i'll be getting into even my insurance choice now :/

Reply 2186

Oink123

Original post by blush.ox

thats what i did, although i did it wrong initially lol. What did you get for the pH on the opp page?

Well most people got 2.1 or something but I got 1.92/1.82 so I did something wrong somewhere. I hope I get marks for working :frown:

Reply 2187

Srai

I was kinda worried about the exam because I hadn't really done much revision, but it surprisingly wasn't that difficult.
The topics were all ones that I remembered being taught, and the rest, I worked out intuitively - and some logical thought.

Overall, I'd say not bad. Expecting 80%-90%.

Also, this is science guys. It's not merely an exam. The questions weren't that difficult if you had been trained to think critically - though, that would not entirely be the fault of you, as most curriculums focus more on solving repititive sets of problems rather then thinking critically and applying what you know to more complex phenomena and context.

Reply 2188

amyyy24

Original post by Kalamari Dave

?) % of Cu in Brass question
Equations with state symbols:
Cu (s) + 4HNO3 (l) --> Cu(NO3)2 (aq) + 2NO3- (aq) + 2NO + 2H2O
Cu2+ + 2I- (aq) --> CuI (s) + 0.5 I2 (aq)
(one more which i can't rememebr)

I think it was removing excess acid with OH-
so it was
H+ + OH- --> H2O

Reply 2189

boba

does anyone know the typical grade boundaries for this paper?

Reply 2190

Schoolio93

Original post by middle92

**** got
second order, but i think i got the working for the rest right.ECF ECF! drew a tangent to the initial rate then concentration decrease over time?

I got second order, too. Do we get ECF throughout?

Reply 2191

VetApplicant2011

Original post by 786girl

58/100 = A

plus a tangy sweet as compensation for mental torture.

did you make that up? I certainly hope its around that

Reply 2192

scienceboy

Original post by mathsmad

This is the second paper by OCR in a week that has just been way of the mark. We need to something about it.
The people who created the group on facebook for biology are telling us to stop moaning on the biology page (rightly so) ... someone make a chemistry facebook page? i dont have facebook (dont trust meself to not speand my life on it^^)
In my opinion... The governments are tied to the exam boards. If we mess up this year and dont get in.. we will be paying the higher tuition fees. So they win.
THIS HAS TO STOP.Anybody with me?

i had this exact discussion with the people from my class after the exam. i hate to be all conspiracy theorist, but it seems a TINY bit odd that the year before uni fees skyrocket to £9000 per year all the exams are ridiculously difficult. compare F324 and F325 this year with 2010 and there's a huge difference in the difficulty of the papers.

thanks OCR.

Reply 2193

Jtking3000

Original post by Kalamari Dave

I disagree with your monomer, they wanted 4,4 bipy not 2,2 bipy

Reply 2194

Kalamari Dave

Original post by boba

does anyone know the typical grade boundaries for this paper?

Last two times it was ~60/100 raw marks for an A (120 UMS).
Don't know how its gonna be this time, quite a few people thought it was good, quite a few thought it was horrible.

Reply 2195

Student21

Anyone else got F224 next week. I dont even feel like revising anymore. I was planning to go through that again for the 3rd time but after this i just feel OCR is going to **** us all again

Reply 2196

tessfoley

Original post by amyyy24

I think it was removing excess acid with OH-
so it was
H+ + OH- --> H2O

It was more complicated as it formed a solid precipitate so it didnt cancel

Reply 2197

CoventryCity

Does any one have an answer for the Kc Calculation and the hydration of Mg2+
I got Kc as 45
And the hydration of Mg2+ as -2300 or something similar can't remember exact value

Reply 2198

Gemma2010

Original post by Heatheroink123

For the weakest acid to strongest acid thing, I got ethanoic as the weakest and pyruvic as the strongest. My method being the higher the pKa, the lower the Ka and the lower the Ka, the weaker the acid. Can anyone confirm this?