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

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I think ppl need to say it in the news about how unfair
the exam was!!!! Too much reading and too much random questions!!!

Reply 2861

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..?

Reply 2862

Jsmalley1

does anyone have any clues about the coursework ums? and what kind of raw mark (out of 40) would be an a?!

Reply 2863

wilsea05

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%

Reply 2864

LilacTweet

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 :biggrin:

. Well good bye A in chemisty, it was never going to happen anyway :getmecoat:

.

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!

Reply 2865

Student21

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?

Reply 2866

Thuzz

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 :frown:

oh well a couple marks for stating the half life and saying it was second order hopefully

Reply 2867

HEC14

Original post by wilsea05

Thankyou!
This is exactly what i did :smile:

However, all the very clever people at my school seem to have got half of my answer :/

Reply 2868

Killmepls

Original post by wilsea05

thats 9 marks gone... lol , do you remember what all the ionic equations where for 1 and 2?

Reply 2869

Masderchef

Original post by wilsea05

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?

Reply 2870

wilsea05

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?