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

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    (Original post by jasonrose98)
    I'm sure I did. Was there another way? I ended up with 4.(something) mol anyways

    I don't know, some people didi it using the one which involves molar mass... I think I got that too but i can't remember
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    (Original post by asinghj)
    Mass of gas / Mr of gas
    I never even thought of that
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    (Original post by chloelaura27)
    I don't know, some people didi it using the one which involves molar mass... I think I got that too but i can't remember
    I did the whole question like 3 times without looking at what I'd done the previous time and kept getting the same answer (which I now can't remember) so hopefully its fine
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    (Original post by asinghj)
    Mass of gas / Mr of gas
    I was going to do that but it was a gas????
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    (Original post by SGHD26716)
    When thinking about grade boundaries we are to think about how people found it in general. I don't think every other person is getting 95% in them.
    Would you say the TSR population is representative of all the people who did the exam?

    I think 105 for an A. It would be as high as 115. A person who drops 10 marks in both papers (gets 86%) will only be 5 marks of a B. That is why O think 114-115 boundary is too high.
    I agree with you. TSR population might not provide an actual representation so an A might be between 108-112 in my opinion.
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    (Original post by jasonrose98)
    I never even thought of that
    I thought that n= v/24000 wouldn't work as the question wasn't at RTP but you got the answer 4.something moles so 🙃🤑
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    (Original post by chloelaura27)
    I was going to do that but it was a gas????
    Still works because you had the mass and could calculate the Mr
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    Someone may have mentioned this before, but for the electrontic config was it an Mg atom or ion? I was like 99% sure it was atom but loads of people from my college said they changed it to ion at the last minute
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    (Original post by jasonrose98)
    Someone may have mentioned this before, but for the electrontic config was it an Mg atom or ion? I was like 99% sure it was atom but loads of people from my college said they changed it to ion at the last minute
    It said atom, I'm sure of it
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    unofficial mark scheme ?
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    (Original post by jasonrose98)
    Someone may have mentioned this before, but for the electrontic config was it an Mg atom or ion? I was like 99% sure it was atom but loads of people from my college said they changed it to ion at the last minute
    it was an atom, I looked over it a couple of times to make sure 😅
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    (Original post by amysed)
    it was an atom, I looked over it a couple of times to make sure 😅
    I felt crushed when everyone said they'd done different 😅I came out thinking I'd done well
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    where is the unofficial mark scheme???. please tell me the link for it. thanks
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    (Original post by iamDev)
    On the last question i messed up the formula and got propanoic acid. However i stated that the m/z is 88 and stated that there is an o-h bond and c = o bond. I stated that its a carboxyllic and and what the peaks 73 and 43 on the mass spec referred to. How many marks do you reckon ill get? Im thinking 2 max and possibly 0
    if you got the empirical formula right and the fact that it is a carboxylic acid from the absorptions/peaks, then I guess you would get 3 out of 6
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    If you labelled Ea on that endothermic diagram, will you lose a mark
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    (Original post by usmanahmed321)
    it was butanoic aCid
    you had TO times the EF C2H4O by two to get C4H802 OF WHICH THE MR WAS 88
    THERE WAS ALSO AN M/Z PEAK AT 88 SUGGESTING IT WAS BUTANOIC ACID
    IT COULDNT HAVE BEEN C2H40 SIMPLY BECUASE THAT ISNT A CARBOXYLIC ACID
    THE IR SPEC CLEARLY INDICATED IT WAS A C ACID
    THE MAS SPEC ALSO SAID THE MOST INTENSE PEAK WAS CAUSED BY A CARBOCATION WHICH WAS AT 43 OR 44
    SO THE MR WAS 88
    anyone agree?
    Agreed. That can be the only way.
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    (Original post by nwmyname)
    Agreed. That can be the only way.
    it is methylpropanoic acid actually guys. it said that it was a secondary carbocation
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    (Original post by Jitesh)
    Don't think peaks like 73 worked for butanoic acid.
    Nope I Checked it did work
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    What would I get for the last question if I didn't talk about the other peaks on the mass spec?
    I started off by saying it had to be a carboxylic acid because of the IR spectrum, then I used the ratios of elements to make the empirical formula, and then the second to last peak on the mass spec (88) to work out the molecular formula and then ran out of time. I was going to look at the other peaks but didn't get a chance so just wrote down butanoic acid. Would I lose more than 2 for this?
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    For the enthalpy question, did you have to label the axes and label Delta H?
 
 
 
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