OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012

reading this makes me so nervous! did anyone else think it was quite a tough exam in comparison?

To be honest, I think it was one of their better papers. It seemed to test broad and shallow, rather than narrow and deep - if you see what I meant

Reply 3981

user977153

Original post by Yabdi1

Exam went okay, what did everyone get for the last question?

91.77%

Reply 3982

Alexdaman93

2

Original post by DoctorVertigo

did you have to put the moles in the buffer question or the concentrations?

Concentrations.

Reply 3983

karo16

What do you think the grade boundaries will be? Was it an overall hard or easy paper?
I thought it wasn't tooo bad... I could have done better on it.

Was confused about the shifting of equilibrium by bubbling of CO2 :s-smilie:

I heard it was meant to react with water to make H2CO3 ....

Reply 3984

user977153

Original post by Alexdaman93

Concentrations.

you sure?

Reply 3985

Cath-ay

Original post by DoctorVertigo

did you have to put the moles in the buffer question or the concentrations?

concentrations, but moles and concs were the same in this question anyway

Reply 3986

LifeIsGood

12

Original post by Chubba2394

If anyone remembers and and if you got it right (i think it was 98.1 or something) can someone put their working out the the last question the percentage purity. everyone i asked said they got 90 something and i didnt get anywhere near that and i really want to understand it... :frown:

I don't remember the exact figures

But I did:
1) n = c*v/1000 and that gives you the moles of MnO4-

2) I multiplied by 2.5 to get the moles of S2O3-

3) Then I multiplied it by 4 to get from 25cm^3 --> 100cm^3

4) I then calculated the molar mass of Na2... = 126.1gmol-1

5) Use n = m/M and find what m is so: m = n * M

6) Got the mass of 0.66.../(original mass given in the question) * 100 = 91.7%

Reply 3987

holahola

Original post by Tyrone-C

(Nh4)2PtCl6

Bond angle around Ptcl6: 90 degrees

Lol i asked to go to the toilet during the exam, i googled this up on my phone while there, little did they know i had my phone in my pocket.
A* please

naat good

Reply 3988

kingam

Original post by myyrh

0.94somthing

I got 1.something :frown:

Reply 3989

user977153

Original post by Cath-ay

concentrations, but moles and concs were the same in this question anyway

yayyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy

Reply 3990

SmithytheDrummer

6

For the bidentate ligands did anyone put the -.on each O atom, or lone pairs on the N atoms on the other ligand?

Reply 3991

Chubba2394

Original post by LifeIsGood

I don't remember the exact figures

But I did:
1) n = c*v/1000 and that gives you the moles of MnO4-

2) I multiplied by 2.5 to get the moles of S2O3-

3) Then I multiplied it by 4 to get from 25cm^3 --> 100cm^3

4) I then calculated the molar mass of Na2... = 126.1gmol-1

5) Use n = m/M and find what m is so: m = n * M

6) Got the mass of 0.66.../(original mass given in the question) * 100 = 91.7%

aaahmmaagaad i did exactly that except for multiplying by 4 oh dear :frown:

hopefully ill get method marks.. thanks for that

Reply 3992

myyrh

9

Original post by SmithytheDrummer

For the bidentate ligands did anyone put the -.on each O atom, or lone pairs on the N atoms on the other ligand?

Yeah I put minus charges on the O atoms and N atoms.

Reply 3993

Aa234

Original post by Tyrone-C

(Nh4)2PtCl6

Bond angle around Ptcl6: 90 degrees

Lol i asked to go to the toilet during the exam, i googled this up on my phone while there, little did they know i had my phone in my pocket.
A* please

Tut tut

This was posted from The Student Room's iPhone/iPad App

Reply 3994

Cath-ay

Original post by SmithytheDrummer

For the bidentate ligands did anyone put the -.on each O atom, or lone pairs on the N atoms on the other ligand?

i put - on the 2O atoms, but didn't put lone pairs on the N. do you think we had to?

Reply 3995

user977153

can't believe i got the Kc question wrong...

Reply 3996

mazE12

Original post by DoctorVertigo

anyone else thought the buffer question was far too simple for 5 marks?

i thought exactly this! i even put a star next to it so that at the end i could go back because i couldn't understand how it could possibly be 5 marks worth of question. Especially when other questions took far longer to work out and were only 1/2 marks

Reply 3997

gerrard1892

7

Original post by Tyrone-C

(Nh4)2PtCl6

Bond angle around Ptcl6: 90 degrees

Lol i asked to go to the toilet during the exam, i googled this up on my phone while there, little did they know i had my phone in my pocket.
A* please

Well you have done well lol, it asked for the metal ion being just pt and cl
Hope you put the NH3 in? serves you right if you have.

Reply 3998

AdamWeeden

1

Original post by Alexdaman93

To be honest, I think it was one of their better papers. It seemed to test broad and shallow, rather than narrow and deep - if you see what I meant

Comparing it to June 2011 with Magic Tang, it was fairly easy.

Reply 3999

user977153

Original post by Tyrone-C

(Nh4)2PtCl6

Bond angle around Ptcl6: 90 degrees

Lol i asked to go to the toilet during the exam, i googled this up on my phone while there, little did they know i had my phone in my pocket.
A* please

hahaha i hope they find out who you are and get disqualified you cheating bugger!

OCR Chemistry A F325 Equilibria, Energetics and Elements Wed 13 June 2012

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