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OCR Chemistry A Exam Thread (Breadth - May 27 2016 and Depth - June 10 2016)

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Like this, idk if that's Born-Haber

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Is it a mistake btw that it has Energy Change of formation? Might be an r actually, but I think I've read it as an f in the book before

Reply 441

Sarephine

Did You Do The Old Spec? Maybe Thats Why Your One Says 60

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(edited 7 years ago)

Reply 442

BTTaz

What was the molecule with no permanent dipole.
I put trans 2,3 dichloro but-2-ene (think it was B)

Reply 443

Jitesh

Original post by BTTaz

What was the molecule with no permanent dipole.
I put trans 2,3 dichloro but-2-ene (think it was B)

It gave E/Z options but yeah that would be E-2,3-dichlorobut-2-ene

Reply 444

tizzaclaire98

Original post by Clintbarton

Was it two marks or one mark? You usually get a mark if you wrote the correct equation. :smile:

Could be worse - I forgot to x100!!

Reply 445

ashbawa

Original post by CheeseIsVeg

Damn

Spoiler

Sometimes they allocate marks for both ways, as you added 50cm^3 to heat something up which happened to also be 50. it depends on the mark scheme. I did another question like this where they added magnesium to the solution and i did the mass of both added together but it also awarded marks for using the solution only

Reply 446

MsDanderson

Original post by iamDev

So pissed with myself. I clearly didnt read the question. I wrote CrCl3H12O6 and didnt realise is was water of crystalisation

Same

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Reply 447

oni176

Original post by KevinClyde

What did people get for (delta)H of reaction? I think I got 58.5 or something like that. Worked out q=4000(odd)J and divided by the mol of the substance you were provided with.

Yeah I got that too, -58.5..

Reply 448

oni176

My predictions for Depth:

- Drawing reaction mechanisms (didn't come up on breadth that much other than some of the basic questions on Multiple Choice where a question on identifying their names and the propagation step for free-radical substitution came up)

-Isomers

-Drawing Boltzmann distribution graphs and collision theory

- Ionic, covalent and metallic bonding structures

- Combustion of alcohols/alkenes + drawing equations

-Practical investigations - Titration is the famous one

-Percentage yield/ applying basic mole questions

- Polymers (why it is sustainable, drawing repeat units etc)

-Ozone depletion

-Trend in Group 2 elements, uses etc.

-Definition questions + average bond enthalpy calculations.

I have a feeling that one of the 6 marker is going to be based on one of the reaction mechanisms for some reason.

(edited 7 years ago)

Reply 449

Mancdude

Original post by Nikosunway

Total marks : 70.

80% out of total : 70* 0.8=56. Any questions?

Hey Dude my fault for the confusion.
Two OCR chemistry exams this morning.

We talking at cross purposes. 80% is normally threshold but if there are 60 or 70 marks available that makes a difference :smile:

My fault for the confusion.

Reply 450

oni176

Although the paper seemed alright with a couple of questions that requires thought and quite challenging, I think the grade boundaries will be:

My prediction:
A - 54
B - 47
C - 40
D - 33
E - 27

The paper wasn't too difficult apart from the last question, perhaps. However, this is a new specification so examiners will take that factor into account. Some questions also took a long period of time to complete as well, so some students may not have probably had sufficient time to check their answers at the end.

Reply 451

isaac_wood_

Did anyone divide 4.2 (grams of copper in the coin) by 63.5 (Ar of Cu in the periodic table) or by the value you obtained in the first part (63.166) get the mol of copper? The correct one should be by 63.166, if i did it by 63.5 would i get any marks?

Reply 452

woop185

What was the mole value in the enthalpy change of reaction question?

Reply 453

Azadi

Can anyone who can get hold of todays new as chemistry paper please forward it to me so i can see the way how the questions are being asked in this new spec as i am having a mock which will determine my predicted grade for uni. Many thanks.

Reply 454

oni176

What did people get for Question 3 on multiple choice that asked you the volume of the gas or whatever it was? I got 120cm3, can't remember which option it was.

Reply 455

11234

Can anyone remember the chemicals in the enthalpy change question

Reply 456

11234

Original post by oni176

What did people get for Question 3 on multiple choice that asked you the volume of the gas or whatever it was? I got 120cm3, can't remember which option it was.

I think I got 300cm3

Reply 457

Fish40

Original post by 11234

Can anyone remember the chemicals in the enthalpy change question

2KI and Something

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Reply 458

h3rmit

Original post by 11234

I think I got 300cm3

Original post by oni176

What did people get for Question 3 on multiple choice that asked you the volume of the gas or whatever it was? I got 120cm3, can't remember which option it was.

I got 300cm^3, the volumes are independent of the gases' molecular formula (for the n=v/24 approximation), so you essentially have 2.5 moles of gas. v=24000/2.5 = 300cm^3

Reply 459

11234

Original post by h3rmit

I got 300cm^3, the volumes are independent of the gases' molecular formula (for the n=v/24 approximation), so you essentially have 2.5 moles of gas. v=24000/2.5 = 300cm^3