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OCR B (Salters) Chemistry F331 (Chemistry for Life) Thursday 23rd May Exam Discussion watch

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    (Original post by Ikklemini)
    Hey what did everyone get for the years from the half life question? I got something like 26000 years ?!
    I'm pretty sure that I got 18,000.
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    I think it went alright!

    As I'm in Year 13, it is a LOT more straightforward that A2 stuff. Hoping for above 45 but I know I've made some stupid mistakes.
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    (Original post by autodidactmedic)
    Does anyone remember what the final few questions were on the back page? Starting to worry that I missed a whole page, I was so exhausted for this exam :confused:
    What does the peak show ? something like that?

    What is the ion used - something like that

    Why is there a peak at 18/z?


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    (Original post by autodidactmedic)
    Does anyone remember what the final few questions were on the back page? Starting to worry that I missed a whole page, I was so exhausted for this exam :confused:
    It was about mass spec and Oxygen - 16
    tooth enamel and how there's oxygen because of water

    it was about m/z of 18... what ion was it? (1)

    and what does the height of the peak mean (1)

    and why there was an m/z of 20 (1)

    don't worry, it's over now.
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    (Original post by JamesMartinez)
    Yeah you'll be fine I bet, and back page questions are a joke, they're asking to catch people out and it's annoying.
    Yeah I know, at least I'll be on my guard for any in future exams.
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    (Original post by krisshP)
    One question was about writing a reaction. It was worth only 1 mark and it did NOT mention anything on state symbols. I wrote the reaction, but didn't put state symbols since I was a bit unsure with what the state symbols would be or that reaction and I didn't want to risk showing incorrect state symbols. Is this okay?
    No it doesn't matter if you haven't put state symbols. The question didn't ask for them so in the markscheme it would just say "Ignore state symbols".
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    (Original post by anthonyrf)
    I think it went alright!

    As I'm in Year 13, it is a LOT more straightforward that A2 stuff. Hoping for above 45 but I know I've made some stupid mistakes.
    I'm in the same boat as you, I thought it was alright, but the first question (20 marks) were incredibly easy? I feel like the grade boundaries are going to be so high again (although I'm hoping otherwise)
    50 for an A again is not good
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    (Original post by SyedaK)
    What did people were for the thermal stability question?


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    I wrote about limewater being a test for the presence of CO2 by going cloudy and that Strontium is more thermally stable than Calcium (as when you go down Group 2, thermal stability increases) meaning that limewater would go cloudly quicker for calcium as more CO2 will be produced in a quicker time than that of Strontium. I think that's correct, hopefully!
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    (Original post by Kathiye)
    On the thermal stability I wrote something ridiculous about how the mass of that substance will decrease more if the thermal stability is lower... think I'll get any marks for it? xD I completely forgot about limewater. I think that I got the mark for saying that strontium is more thermally stable, though.

    Also, I got confused on the beta radiation one. >.< Just had a stupid moment and decreased the mass number by one rather than the proton number. I don't think I'll get any marks for that. xD
    I completely messed up the thermal stability. Wrote completely the opposite. I probably lost around 20 marks for the whole paper.

    Wasn't the beta radiation answer 14 and 7 N


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    (Original post by SyedaK)
    I completely messed up the thermal stability. Wrote completely the opposite. I probably lost around 20 marks for the whole paper.

    Wasn't the beta radiation answer 14 and 7 N


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    The beta question was definitely 14 & 7 Nitrogen.


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    (Original post by tasniaa)
    I'm in the same boat as you, I thought it was alright, but the first question (20 marks) were incredibly easy? I feel like the grade boundaries are going to be so high again (although I'm hoping otherwise)
    50 for an A again is not good
    The first question was very nice! Not sure about biofuels being sustainable though, I said some rubbish about them being renewable (sounds like GCSE) and being carbon neutral they don't produce any carbon substances when burnt e.g. Carbon dioxide. :/

    I just want a B overall so need as high as possible in AS because A2 is so bloody hard!!!
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    (Original post by hhustad)
    The beta question was definitely 14 & 7 Nitrogen.


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    Well thank The Lord! I'm not going to expect much from this paper. It'll lead me to feel disappointed.


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    How can so many people complain about missing the last page. They weren't trying to catch anyone out, they even wrote in bold letters "QUESTION 4 CONTINUES ON THE NEXT PAGE". You can't blame the exam board, you just need to read what's on the paper. Sorry if this offends anyone that missed it, but I don't see how it's anyone's fault but your own if you forget to read something, no point complaining about it now, what's done is done, and chances are those 3 marks won't affect your grade by much anyway.
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    (Original post by SyedaK)
    Then you definitely have a strong change to go Cambridge. And wow! Full marks - I got 45/60


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    Hopefully! And only cause our teachers did an afterschool thing where they did the stuff we needed to know for it but in a different context (so not entirely cheating) and we just had to learn our notes for the next day. Agree with whoever said the coursework part needs to change though, so unfair on schools that actually do it properly.
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    (Original post by RoastHam)
    Hopefully! And only cause our teachers did an afterschool thing where they did the stuff we needed to know for it but in a different context (so not entirely cheating) and we just had to learn our notes for the next day. Agree with whoever said the coursework part needs to change though, so unfair on schools that actually do it properly.
    That's true. But I'm disappointed in myself because we had re-sits for the coursework and I didn't improve by much.


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    (Original post by tasniaa)
    I always screw up the maths for goodness sake.

    It was MgCO3 = 0.2
    produces CO2
    1:1
    Mr MgCO3 = 84.3
    Mr CO2 = 44

    i did 0.2/84.3 = y

    y x 44 = 0.1

    (0.1 /24)x 1000 = 4.16



    can someone please explain how to answer this question correctly?
    I calculated the Mr of MgCO3 which was 84.3 I think.

    The question told you that we had 0.2g of MgCO3 so the no. Moles of MgCO3 was 0.2/84.3 = 0.00237247...

    ratio of CO2 to MgCO3 was 1:1 so moles of CO2 = 0.00237247...

    therefore Vol. of CO2 in cm3 was 0.00237247... x 24000 which = 56.94 (2dp)
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    (Original post by Hamster96)
    How can so many people complain about missing the last page. They weren't trying to catch anyone out, they even wrote in bold letters "QUESTION 4 CONTINUES ON THE NEXT PAGE". You can't blame the exam board, you just need to read what's on the paper. Sorry if this offends anyone that missed it, but I don't see how it's anyone's fault but your own if you forget to read something, no point complaining about it now, what's done is done, and chances are those 3 marks won't affect your grade by much anyway.
    It was just in the pressure of exams you do stupid things like that, exam boards should know that so should try and minimise the chances of something like that occurring. And you're right we'll just have to be prepared for it if it happens again.
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    (Original post by anthonyrf)
    I calculated the Mr of MgCO3 which was 84.3 I think.

    The question told you that we had 0.2g of MgCO3 so the no. Moles of MgCO3 was 0.2/84.3 = 0.00237247...

    ratio of CO2 to MgCO3 was 1:1 so moles of CO2 = 0.00237247...

    therefore Vol. of CO2 in cm3 was 0.00237247... x 24000 which = 56.94 (2dp)
    I got 18.000 for number of years about the half life question

    I also got 56.9 for the volume in cm3
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    (Original post by CoolRunner)
    I got 18.000 for number of years about the half life question

    I also got 56.9 for the volume in cm3
    I completely messed up the half life question. :/
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    (Original post by anthonyrf)
    I calculated the Mr of MgCO3 which was 84.3 I think.

    The question told you that we had 0.2g of MgCO3 so the no. Moles of MgCO3 was 0.2/84.3 = 0.00237247...

    ratio of CO2 to MgCO3 was 1:1 so moles of CO2 = 0.00237247...

    therefore Vol. of CO2 in cm3 was 0.00237247... x 24000 which = 56.94 (2dp)
    jihadbexdnw feih
    3 marks down the drain.

    I think I've got 48/60
    Don't think that'll be good enough for an A
    Damn :'(
 
 
 
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