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

1. I think ppl need to say it in the news about how unfair
the exam was!!!! Too much reading and too much random questions!!!
2. does anyone actually know weather the answer to the last question was 66.6/7/8 or 33.? %?!
Seems like there is an evenish spilt between the two answers..?
3. does anyone have any clues about the coursework ums? and what kind of raw mark (out of 40) would be an a?!
4. (Original post by HEC14)
does anyone actually know weather the answer to the last question was 66.6/7/8 or 33.? %?!
Seems like there is an evenish spilt between the two answers..?
2.8g of brass, all the stuff before step 4 was irrelevant tbh.
the equation for copper and KI is
2Cu2+ 4I- -> 2CuI + I2

then that was titrated against sodium thiosulphate with the eqation
2S2O32- + I2 -> S4O62- + 2I-

so 2 moles of thiosulphate = 2 moles of copper
0.0298x0.1= moles of thiosulphate = moles of Cu2+
=0.0029x10 = moles in the 250cm3, x 63.5 = 1.8923g/2.8x100 = 67.58...%
answer asked for one decimal place so its 67.6%
5. (Original post by blush.ox)
Lol i was basically just asking what 55 raw marks would equal in terms of UMS and you've answered my Q soo thankyou . Well good bye A in chemisty, it was never going to happen anyway .

Yes i know what you mean. I just wanted to know where i would stand with UMS based on if i got like 55 marks on this paper, which i've just looked through. That would help me see how many i would need in the F324 paper :/ to get an A, but it seems impossible, i might not even make the B :/.
I think you usually multiply it by like 1.6-1.8 to get to UMS..
Going by Jan's grade boundaries 65x 1.85 =120 UMS (ish)
so 55x 1.85= 102UMS

Although it's not quite like that..... this is just a (very) rough estimation!
6. (Original post by susan23)
calculate your whole A level UMS marks...not indivitual grades in each module...because even if you get A grades in all your modules and practicals you STILL DONT GET AN A overall in A level....

so add up your...

unit 1
unit 2
practical AS
unit 4
unit 5 (assume)
practical A2

add them in terms of UMS!

and if its 480 or above...it would be an A ...
Well i've misplaced my marks for those units. Is there any way of getting hold of them. Do OCR send them out if requested and is there a fee?
7. (Original post by Rickesh)
I didnt get that, nor did a few people I asked, they said its not a first order, as it didnt have a constant half life. when i worked it out i didnt get a constant half life?
yeah i got second order
but i messed the rest of the question up
oh well a couple marks for stating the half life and saying it was second order hopefully
8. (Original post by wilsea05)
2.8g of brass, all the stuff before step 4 was irrelevant tbh.
the equation for copper and KI is
2Cu2+ 4I- -> 2CuI + I2

then that was titrated against sodium thiosulphate with the eqation
2S2O32- + I2 -> S4O62- + 2I-

so 2 moles of thiosulphate = 2 moles of copper
0.0298x0.1= moles of thiosulphate = moles of Cu2+
=0.0029x10 = moles in the 250cm3, x 63.5 = 1.8923g/2.8x100 = 67.58...%
answer asked for one decimal place so its 67.6%
Thankyou!
This is exactly what i did
However, all the very clever people at my school seem to have got half of my answer :/
9. (Original post by wilsea05)
2.8g of brass, all the stuff before step 4 was irrelevant tbh.
the equation for copper and KI is
2Cu2+ 4I- -> 2CuI + I2

then that was titrated against sodium thiosulphate with the eqation
2S2O32- + I2 -> S4O62- + 2I-

so 2 moles of thiosulphate = 2 moles of copper
0.0298x0.1= moles of thiosulphate = moles of Cu2+
=0.0029x10 = moles in the 250cm3, x 63.5 = 1.8923g/2.8x100 = 67.58...%
answer asked for one decimal place so its 67.6%
thats 9 marks gone... lol , do you remember what all the ionic equations where for 1 and 2?
10. (Original post by wilsea05)
2.8g of brass, all the stuff before step 4 was irrelevant tbh.
the equation for copper and KI is
2Cu2+ 4I- -> 2CuI + I2

then that was titrated against sodium thiosulphate with the eqation
2S2O32- + I2 -> S4O62- + 2I-

so 2 moles of thiosulphate = 2 moles of copper
0.0298x0.1= moles of thiosulphate = moles of Cu2+
=0.0029x10 = moles in the 250cm3, x 63.5 = 1.8923g/2.8x100 = 67.58...%
answer asked for one decimal place so its 67.6%
I got roughly 67.6% too. As soon as my calculator display showed this figure, I knew it was correct. The past paper questions seem to indicate this percentage anyway with brass questions.

Do you remember what you put for the 3 ionic equations? and also how many marks were they worth?
11. (Original post by Killmepls)
thats 9 marks gone... lol , do you remember what all the ionic equations where for 1 and 2?
yeah you had to know that Cu2+ goes to Cu1+ otherwise you would've got the mole ratios wrong.

urmmmmm

step 4 was 2Cu2+ +4I- ->2CuI + I2
cant remember the other 2 and cbaaa to figure them out haha
can you remember how many marks the question was in total?
12. (Original post by Andygunner93)
I got 33.8% as well
same
most ppl got 60 odd percent though, but if we do get it wrong hopefully we get ECF
13. (Original post by susan23)
calculate your whole A level UMS marks...not indivitual grades in each module...because even if you get A grades in all your modules and practicals you STILL DONT GET AN A overall in A level....

so add up your...

unit 1
unit 2
practical AS
unit 4
unit 5 (assume)
practical A2

add them in terms of UMS!

and if its 480 or above...it would be an A ...

What would be a B?
14. (Original post by percy93)
What would be a B?
420 in the overall A level.
15. anyone know how many marks the Kc question was worth?
16. and also how many marks was it to work out the rate constant?
17. (Original post by pan_93)
anyone know how many marks the Kc question was worth?
6y?
18. can someone who remebers or has the paper put down all the marks required for each question?? thanks
19. (Original post by Flint_09)
6y?
6 marks?

im just trying to add up my total....

you know how many marks for working out the rate constant using the graph?
20. (Original post by pan_93)
6 marks?

im just trying to add up my total....

you know how many marks for working out the rate constant using the graph?
either 5 or 6 and for rate constant...7 or 9 marks.

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