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

Reply 1940

acetic acid is ethanoic acid lol

but i realised i square rooted something along the way which is wrong, so you are probably right.

Oh right lol, and IDK im not that confident on that one =S

Reply 1941

akhan123

can sum1 plzzzz make a unnofficail mark scheme

Reply 1942

Vidja

Original post by Student21

I put enthalpy positive cos its endothermic and entropy negative as solid to liquid is more disordered. Am i right?

Solid to liquid means it's more disorded

Entropy is a measure of disorder

More disorder means higher entropy

It was positive.

Reply 1943

Student21

8

Original post by RodrigoB

exactly what i put
f***k yeah

Well at least i got one right. 1/100 - big time fail! :frown:

Edit: using the above post i now know i got it wrong :frown:

0/100 now

Reply 1944

Lissa-154

Original post by Student21

I put enthalpy positive cos its endothermic and entropy negative as solid to liquid is more disordered. Am i right?

If something's becoming more disordered, the entropy is increasing, so it's positive i'm afraid :/

I also put enthalpy as positive because of bonds being broken when ice melts :smile:

Reply 1945

joe3469

Original post by Heatheroink123

For the ice melting thing, I put entropy positive, enthalpy negative, and then changed enthalpy to positive as it's endothermic? Anyone else get this?

Yeah me too :smile:

Had to think for about for a while though but then it became obvious. Breaking bonds = energy required = endothermic!

Reply 1946

GiraffePoacher

Was definitely a toughie! Biggest problem was lack of time.

Wasn't sure about the precipitate in step 4 of the last question... what did everyone else get?

In the "magic tang" question I discussed that a buffer at pH 3.5 (or whatever it was) would most likely be lower than that in a human mouth (I'm no biologist) so as it reacts in the mouth the equilibrium of the buffer would work to counteract the effect of the higher-pH mouth by dissocating into H+ ions, which the question earlier stated was responsible for the "magic tang". This is significant, because had the buffer been a pH higher than the mouth, H+ would associate with the salt instead and it would taste bitter. Thoughts?

Reply 1947

may bug :)

'magic tang' 'one giant slap in the vadge!' I just innocently chatted about buffers in the hope i could save myself.... a little

ps. gee wee if you're out there... smile :smile:

Reply 1948

blush.ox

15

Original post by cawse879

wasnt sure about the condensational polymer question deffo no marks for that.
was the co ordiantion number 4 and molecualr formual c10h8n2? Buffer question was tricky.
the entropy one was easy but the last tick i put decreased cause just looked at gaseous moles.
for the long transition element question you didnt have to always use nickel did you?
bond angle- 90 degress.
precipitate- ni(oh)2
first formular i put ni(cl)4 2- ?
the isomerism in the complex ion was optical wasnt it?
the battery i got ni reduced +3 to +2.
and cadmium oxidised 0 to +2.

I got all of this, apart from the buffer Q, had to leave it out :sigh:

.

Reply 1949

RodrigoB

4

Original post by Amit619

Haha, I got 33% too, fiddled with the numbers and ended up with that. I'm so depressed, and F324 resit is gonna finish me off.

SAME situation mate

I WAS supposed to be doing great on this chem papers
but so far I am flopping like ****

FUTURE CHEMICAL ENGINEER DEGREE = FAIL

Reply 1950

Vidja

"When counting from [Whatever that bidentate ligand was] you count from the carbon connecting to the other ring"

....
.....
........
...........
..............what the ****?

Reply 1951

susan23

3

Original post by Student21

I put enthalpy positive cos its endothermic and entropy negative as solid to liquid is more disordered. Am i right?

i put enthalp was negative because temperature was 0 making S xT = 0 so the only way G could be less than 1 for feasability was if delta-H was negative?!??!

OMG nooooo thats probably the only thing i thought I got right!?!!?!?

Reply 1952

ruby321

11

Original post by Nymthae

I didn't spend very long deliberating on questions I couldn't do, gently skipped through things and gradually went back to them. I had quite a lot of time but there were a lot of marks I technically didn't attempt so that's probably where my time was from :redface:

If you're confident and fairly quick in your answers you can pick up a lot of time. There wasn't a lot of rubbish reading to do, like the F324 paper in January seemed to have.

Yes that's what I did! Any question I found hard I just left it and I did the last question first because I knew I could do it, just in case I didn't have time! But I know definitely did muck up a lot of questions.

Agree, sometimes most of the information they give you is invalid so you just need to learn how to skip over it and pick out the things you want!

(edited 12 years ago)

Reply 1953

joe3469

Original post by Jtking3000

Anyone else get around 5x10^-3 s^-1 for the rate?

I got something like that, I think about 3 x 10^-3.
Finding a tangent's grandients without differentiation is very vague!

Reply 1954

2141

Original post by susan23

I actually couldnt do the majority of the paper!! I coundlt even do the buffer question1?!??! i dont why it just didnt make any sense?!?! I cudnt do the last question either?!?!? everything about that paper was so ****ed up ...i cudnt do the 3D structure properly...WT ...I dont understand...I revised so much and now I **** it all up....and there were like 4 -9 marker questions...I;ve probably lost 50+ marks...I actually feel like **** now...I seriuosly hope the grade boundaries are REALLY LOW im sorry I dont want 60/100 to be an A I want atleast 40/100 to be an A because that exam was so unfair..well half of it was unfair...CUDNt do ****ing ionic equations....stupid half equations...and they waffle so much...I dont give a **** if you want to make TANGY SWEeTS!¬!! I just want to do the work that was set in my BOOK not your ****ing imagination OCR!"!!! everyone should write emails to OCR...seriously..even if you FOUDN it Ok...because u dont know....!

I couldnd't do those questions either, and I ran out of time. I think I have failed this. I actually feel more confident about F215. Argh, if only I had more time. I don't think the paper itself was bad though, it's just that there wasn't enough time.

Reply 1955

Acta Non Verba

7

Those who put 33%:

Most likely that will only lose you one mark due to ECF. I put 33% as well, so here's hoping.

Reply 1956

Student21

8

Original post by susan23

I actually couldnt do the majority of the paper!! I coundlt even do the buffer question1?!??! i dont why it just didnt make any sense?!?! I cudnt do the last question either?!?!? everything about that paper was so ****ed up ...i cudnt do the 3D structure properly...WT ...I dont understand...I revised so much and now I **** it all up....and there were like 4 -9 marker questions...I;ve probably lost 50+ marks...I actually feel like **** now...I seriuosly hope the grade boundaries are REALLY LOW im sorry I dont want 60/100 to be an A I want atleast 40/100 to be an A because that exam was so unfair..well half of it was unfair...CUDNt do ****ing ionic equations....stupid half equations...and they waffle so much...I dont give a **** if you want to make TANGY SWEeTS!¬!! I just want to do the work that was set in my BOOK not your ****ing imagination OCR!"!!! everyone should write emails to OCR...seriously..even if you FOUDN it Ok...because u dont know....!

I went through the syllabus 4 ****ing times and still ****ed up! 4 times, 4 ****in times. what the hell were we sitting today a PHD paper? i bet even those are easier lol.

Reply 1957

Oink123

7

The questions I know I have got right:

transition metal 7 mark thing (maybe not all the marks but was pretty decent)
1.25 volts thing
oxidation and reduction (it was cd oxidised from 0 to +2 and ni reduced from +3 to +2 right?)
definition of lattice enthalpy
definition of standard electrode potential
why mg has a more exothermic than ca lattice thingy

Reply 1958

gradu

8

Well either I will take a 2nd gap year OR go to uni... tough paper.

Couldn't do last question, and draw that polymer thing hah.

Hopefuly 50% is a C :biggrin:

DDDDDDDDDDDDDDDDD