CCEA AS unit 2 chemistry exam june 2012

Katieh007

7

Hey!

Any idea on what could come up?
Hows your revision going?
and how are you revising??? :smile:

Reply 1

Katieh007

OP

7

what do you think will come up??

Reply 2

Katieh007

OP

7

Please help me with this question!!

15cm3 of a gaseous hydrocarbon at 100degrees wa mixed with excessB] oxygen and exploded. Cooling the products caused a reduction in the volume equivalent to 30cm3 at the orginal temperature. A further reduction of 30cm3 occured on exposure to conc. alkali.

What is the formula of the hydrocarbon??

Reply 3

Fladam

Hi Katie , for a question such as this the formula :
C_XH_Y+ x+y/4 O₂ ---> xCO₂ + y/2 H₂O

May be useful, in the case of cooling the liquid to room temperature the water will condense leaving no water vapour, you should also note that passing through an alkali removes the carbon dioxide, with this you should be able to compare moles or volumes from the equation I have given you above ( ie. Adding alkali reduced by 30cm3 so you can say XCO₂ = 35 cm3)

Hopefully that should lead you along the correct path! Apologies if any of the subscripts are wrong I'm only a new member :smile:

Reply 4

Fladam

Can't seem to edit that on my phone but I meant XCO₂ = 30cm3 not 35

Reply 5

Fladam

Thought it went well enough though I made a few silly mistakes here and there! How did you all find it?

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

Reply 6

BLUERUN

I thought the paper was a lot better then I expected it to be , what mistakes did you make?

Reply 7

Fladam

It definitely wasn't as bad as other years! I got the wrong propagation step for the multiple choice and I said electronic vibrations for one which I think might be wrong... Also drew my E-Z isomers out in full instead of condensing them into the carbon-carbon double bound with two bonds to either carbon... I drew something like

H H H H
| | | |
H-C-C=C-C-H
| |
H H

For the Z isomers but most people did it in the form ( not the exact bonds like this just ah example)

H H
| |
C=C
| |
CH3 CH3

So I don't know if the way I did it was worth any marks.. Rest of it seemed fine.. Especially the 7 marks for the flame rest :biggrin:

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

Reply 8

BLUERUN

Original post by Fladam

It definitely wasn't as bad as other years! I got the wrong propagation step for the multiple choice and I said electronic vibrations for one which I think might be wrong... Also drew my E-Z isomers out in full instead of condensing them into the carbon-carbon double bound with two bonds to either carbon... I drew something like

H H H H
| | | |
H-C-C=C-C-H
| |
H H

For the Z isomers but most people did it in the form ( not the exact bonds like this just ah example)

H H
| |
C=C
| |
CH3 CH3

So I don't know if the way I did it was worth any marks.. Rest of it seemed fine.. Especially the 7 marks for the flame rest :biggrin:

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

Yeah I think it was molecular vibrations although for the E-Z isomers they should still give you the marks if the drawing is correct. I couldn't believe the flame test came up again especially since it came up in January as1 : D. How did you find he 2nd multiple choice question you know the one asking about the RFM of the hydrocarbon?

Reply 9

Fladam

Think it was molecular vibrations. So good job :smile:

.. How many / 75 do you think on that paper for 80 UMS? Sometimes if it's too easy they scale down if you're below average and scale up above average... Lost around 4 there in the multiple choice and maybe 6-8 in the rest of the test ( assuming they mark those isomers wrong and giving myself a few more incase I did something that I'm not aware of yet)

I thought that question was definitely different, I played around with some numbers for 40 seconds though and managed to get 44 (B) as the answer which everyone I asked seemed to get! Fingers crossed... It was practically sheer luck lol

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

Reply 10

BLUERUN

Really not to sure hopefully I haven't lost too many : D ,

Yeah I looked at the question and hadn't a clue what to do so i did ip dip die blue and out but you and got B (44) : D, Although i went back at the end and managed to figure it out and got 44 again.

You know the very last question bond braking and making can you remember you enthalpy change of combustion? , I think mine was -2689 or a couple of hundred around that.

Well all our exams are finished now , can finally stop thinking i should be doing some work : D

Reply 11

Fladam

Just realised how silly my Isomers looked on the pc :P I drew those on the mobile and they were perfect looking on the app, was so proud of myself haha... never mind I guess!

Good job on getting that question, it was definitely one of the hardest multiple choice questions!

Really not to sure hopefully I haven't lost too many : D ,

I'll be hoping the boundary for an A is 60 :P Although apparently they move it up to 62/75 sometimes if the paper is easy :frown:

and Im not sure if that paper was overly difficult lol...

I think mine was -2689 or a couple of hundred around that.

I think I might even have gotten exactly -2689 or so, a lot of my friends said they got the same after the exam!

Well all our exams are finished now , can finally stop thinking i should be doing some work : D

Haha lucky for you, I still have one module left, AS Business studies Unit 2, fun times! Shouldn't be too bad though, I hope to get it all revised within six hours tomorrow and then do a few more hours before bed! Can't wait to finish, however I will end up doing a lot of work and reading over the summer so that I don't think too much about the results, I might even get a head start on C3 for next year! Definitely be nice to get the stress away though!

Any ideas what you'd like to do at uni/ what uni you'd like to go to? If i may ask.. :smile:

Reply 12

BLUERUN

Well good luck for you business studies exam hopefully its a nice paper,
I heard alot of people after the chemistry exam saying they found it quite hard which surprised me a we bit.

I'm think queens university and i think im going to apply for Human Biology or Biomedical science yourself?

Reply 13

Fladam

Thank you very much! :smile:

I heard alot of people after the chemistry exam saying they found it quite hard which surprised me a we bit.

I know it sounds harsh but you have to basically hope that everyone else other than you finds the exam really hard :P

I also am thinking of going to queens! :smile:

Those sound like two very intersting subjects! :smile:

I'd like to either do Physics or Theoretical physics, feeling the pressure this term though because Im not sure if I want to do an Msc or Bsc, and to get an offer for the Msc im going to need at least AAB plus whatever i get in my fourth subject this year... So it will be great to finish! Wish I was going to university after this year though, seeing all the posts on here about people asking what to pack is getting me excited already about going :P

Reply 14

acrawford957

Does any1 remember which option they picked for Q.s 10

Reply 15

calender1994

Original post by acrawford957

Does any1 remember which option they picked for Q.s 10

wat was the question again oh the enthalpy one em i got d cuz on the y axis its entthalpy and not enthaly change :smile:

Reply 16

Fladam

I selected A because the activation energy for D was from the products to the peak of the activation energy... A was the same diagram but with the activation energy from the reactants to the activation energy

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Reply 17

BLUERUN

Original post by Fladam

Thank you very much! :smile:

I know it sounds harsh but you have to basically hope that everyone else other than you finds the exam really hard :P

I also am thinking of going to queens! :smile:

Those sound like two very intersting subjects! :smile:

I'd like to either do Physics or Theoretical physics, feeling the pressure this term though because Im not sure if I want to do an Msc or Bsc, and to get an offer for the Msc im going to need at least AAB plus whatever i get in my fourth subject this year... So it will be great to finish! Wish I was going to university after this year though, seeing all the posts on here about people asking what to pack is getting me excited already about going :P

I know what you mean it's probably not the right thing but when you hear they found it hard it kind of gives you hope the grade boundaries are low.
Good stuff I think I might have applied for physics but I'm not doing maths A level so kinda is a disadvantage , I know what you mean I would much rather be done with A levels now and be going to university rather then another year of school : D.
If you don't mind me asking what school do you go to?

Reply 18

KitschyFox

Original post by Fladam

I selected A because the activation energy for D was from the products to the peak of the activation energy... A was the same diagram but with the activation energy from the reactants to the activation energy

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

I got A for the same reason *hi-fives*

Though I know I've made loads of other tiny mistakes that'll add up :s-smilie:

The paper could've been a lot harder though, so glad they basically ignored all the mechanisms and such :p:

Reply 19

Katieh007

OP

7

Original post by Fladam

Hi Katie , for a question such as this the formula :
C_XH_Y+ x+y/4 O₂ ---> xCO₂ + y/2 H₂O

May be useful, in the case of cooling the liquid to room temperature the water will condense leaving no water vapour, you should also note that passing through an alkali removes the carbon dioxide, with this you should be able to compare moles or volumes from the equation I have given you above ( ie. Adding alkali reduced by 30cm3 so you can say XCO₂ = 35 cm3)

Hopefully that should lead you along the correct path! Apologies if any of the subscripts are wrong I'm only a new member :smile:

Thanks Fladam!!!!! :smile:

unfortunatly did not look at this before the exam!! but think i knew the general idea!! :wink:

CCEA AS unit 2 chemistry exam june 2012

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