Hey there! Sign in to join this conversationNew here? Join for free

ocr a f325 revision thread Watch

Announcements
    Offline

    2
    ReputationRep:
    (Original post by LRJ)
    at 40 seconds? I'm not sure, 0.04 or something like that? I messed up the next question and used the initial rate instead of the rate I found before, for finding k, so I was more concerned about that so don't really remember sorry, I remember finding the initial rate to be 0. 0781 or something, so the rate at 40 should be 0.04 or lower I think.. I might be adding in an extra decimal place there, my mind has been destroyed from C4!
    its fine for K did you use the concentration which was something like , you used the rate from the before part and did the rate of what you got divided by the conc which was something like 5.something
    Offline

    0
    ReputationRep:
    (Original post by otrivine)
    its fine for K did you use the concentration which was something like , you used the rate from the before part and did the rate of what you got divided by the conc which was something like 5.something
    Yeah k = rate/(conc*conc) my k value was completely off but should have picked up 1 of the 2 marks for method hopefully, I don't know if they'll be that lenient though as it was quite simple xD How do you think you've done overall?
    Offline

    0
    ReputationRep:
    (Original post by gemmabug)
    Our teachers told us that for some reason this year our whole year (about 400 doing chemistry) has done a lot worse at the practical side than any other years with a much wider range and they reckoned that the boundaries would be quite different. OCR might be fed up with everyone getting such high marks? I dunno maybe they just accidentally chose us hard practicals but my teacher drew a graph of the normal results vs our results and seemed pretty sure so might be lower!
    hope so!!!!
    Offline

    2
    ReputationRep:
    (Original post by LRJ)
    Yeah k = rate/(conc*conc) my k value was completely off but should have picked up 1 of the 2 marks for method hopefully, I don't know if they'll be that lenient though as it was quite simple xD How do you think you've done overall?


    thanks , when you say conc*conc?

    you mean the K= rate what you got divided by the conc where the line started in the y axis right, at the top?


    okay I guess but question 5 I found the hardest with all the equations and complex, was really confusing
    Offline

    0
    ReputationRep:
    (Original post by gemmabug)
    Our teachers told us that for some reason this year our whole year (about 400 doing chemistry) has done a lot worse at the practical side than any other years with a much wider range and they reckoned that the boundaries would be quite different. OCR might be fed up with everyone getting such high marks? I dunno maybe they just accidentally chose us hard practicals but my teacher drew a graph of the normal results vs our results and seemed pretty sure so might be lower!
    I agree with that coz our college had the worst results in the history of chemistry.... i had 29 marks and my teacher predicted that would be about 45 ums
    Offline

    18
    ReputationRep:
    (Original post by XingBairong)
    :L getting nervous

    According to last year's grade boundaries, my 38/40 in practical would give me 54
    The score according to the unofficial mark scheme range somewhere between 86-93 and it could potentially go lower...
    I'm hoping it won't :L really want that A* Y_Y
    boo hoo :rolleyes:
    Offline

    0
    ReputationRep:
    (Original post by otrivine)
    thanks , when you say conc*conc?

    you mean the K= rate what you got divided by the conc where the line started in the y axis right, at the top?


    okay I guess but question 5 I found the hardest with all the equations and complex, was really confusing
    I had a blonde moment and got confused with the Kc question where you had two concentrations [H2] and [I2], the rate question with only once concentration in the rate equation- benzene-something ? (and H20 was zero order)

    So yeah I looked at the starting concentration on the graph, something like 0.85 moldm-3, and worked out the initial rate to find k, it should be the same value in theory, but I got a different answer to when I used the conc at 40 seconds and the rate at 40 seconds, wasn't far off though, hopefully it still be in range
    Offline

    2
    ReputationRep:
    guys,
    for the rate i did intial / conc

    and then i did inital/ conc at 40???
    Offline

    2
    ReputationRep:
    (Original post by otrivine)
    what did you get for your rate of reaction?
    Is this you otrivine! ;D

    Name:  O.png
Views: 173
Size:  26.7 KB
    Offline

    2
    ReputationRep:
    (Original post by freetown)
    Is this you otrivine! ;D

    Name:  O.png
Views: 173
Size:  26.7 KB
    hahahaha, yes how did you do that
    Offline

    0
    ReputationRep:
    Hello, I was wondering if anyone here could help me out- I'm trying to firgure out what I needed to get in the f325 to get an A overall

    So far I have

    254/300 from AS (ums)
    79/90 f324 (ums)
    I got 35/40 raw marks in A2 coursework

    Thank you
    Offline

    2
    ReputationRep:
    (Original post by I'm-the-moon)
    Hello, I was wondering if anyone here could help me out- I'm trying to firgure out what I needed to get in the f325 to get an A overall

    So far I have

    254/300 from AS (ums)
    79/90 f324 (ums)
    I got 35/40 raw marks in A2 coursework

    Thank you
    Your practical will get you around 46/47 UMS using the June 2012 grade boundaries.

    Therefore you needed a minimum of 101UMS! in f325! ... this is a high grade C
    Offline

    0
    ReputationRep:
    (Original post by freetown)
    Your practical will get you around 46/47 UMS using the June 2012 grade boundaries.

    Therefore you needed a minimum of 101UMS! in f325! ... this is a high grade C
    Thank you! I found that paper so tough- I dunno if I've managed to get that A.
    I remember when I was doing gcses, I thought a- level would be piss easy as you
    only had to do 3 subjects....if I could go back in time I would slap my younger self so hard.
    Thank you Freetown!
    Offline

    2
    ReputationRep:
    (Original post by I'm-the-moon)
    Thank you! I found that paper so tough- I dunno if I've managed to get that A.
    I remember when I was doing gcses, I thought a- level would be piss easy as you
    only had to do 3 subjects....if I could go back in time I would slap my younger self so hard.
    Thank you Freetown!
    Slap you can't have been that bad lol

    any tips for f324 :P you a have great UMS tally so far
    Offline

    0
    ReputationRep:
    Thank you- I just hope it's good enough...

    In terms of tips I just sort of made model answers for the typical benzene questions copied from past paper Mark schemes. They are usually looking for the same few marking points.
    When I was trying to learn all the different structures of aldehydes/key tones/carboxylic acids/esters and all that, I found it quite difficult because they all start looking the same about an hour into revision (for me anyway) so it really helped having one massive mind map type thing, with all of the structures and their respective reactions.
    And look out for questions where they have molecules with different functional groups on them- in the stress of an exam I wouldn't notice them, so yeah. I would scan in my notes but I gave them to a friend who is retaking. I hope this helped. And good luck!
    Offline

    0
    ReputationRep:
    (Original post by zef1995)
    Please correct me if I'm wrong, but I think it was a question where you had to draw the DMGH molecule!
    OH YEAH! I remember now haha THANKS ^-^ Was bugging me for ages!
    Offline

    2
    ReputationRep:
    (Original post by Sarangtaec)
    OH YEAH! I remember now haha THANKS ^-^ Was bugging me for ages!
    That's okay don't worry!
    I hope the exam went well for you
    Offline

    0
    ReputationRep:
    (Original post by zef1995)
    That's okay don't worry!
    I hope the exam went well for you
    You too! ^-^ I just went through the unofficial mark scheme and I feel tons better hahah I know I lost quite a lot on the last one but not gonna stress about this anymore, it's over and done with now I gotta prepare for F324 on Wednesday!
    Offline

    0
    ReputationRep:
    hey for the ph of the buffer question did we have to take away the ph of HCOOH from NaOH or visa versa ( I cant remember which way round it is)?
    Offline

    2
    ReputationRep:
    (Original post by Sarangtaec)
    You too! ^-^ I just went through the unofficial mark scheme and I feel tons better hahah I know I lost quite a lot on the last one but not gonna stress about this anymore, it's over and done with now I gotta prepare for F324 on Wednesday!
    Thank you! It's good that you feel better about it now
    Exactly, one more exam down, that's gotta be a good thing! Good luck for F324, some of my friends are taking that too so fingers crossed for a good paper!
    Have you got to meet any uni offers?
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Should Spain allow Catalonia to declare independence?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.