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    (Original post by Splaffie)
    an isomer ALWAYS has the same molecular formula, they had the same mr but a different molecular formula
    They had the same molecular formula, I even counted in the exam just to make sure
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    (Original post by Splaffie)
    an isomer ALWAYS has the same molecular formula, they had the same mr but a different molecular formula
    they were both only made of carbon hydrogen and oxygen and to hav the same mr would hav to b in the same amount with each which meand they would hav the same molecular formula ?
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    (Original post by neon_reaper)
    They had the same molecular formula, I even counted in the exam just to make sure
    they had the same relative molecular mass but not the same chemical formula, butane has no oxygen and the others did so they are not isomers as soon as you consider that
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    (Original post by Splaffie)
    they had the same relative molecular mass but not the same chemical formula, butane has no oxygen and the others did so they are not isomers as soon as you consider that
    There were 3 molecules, 2 of them were isomers and the third was butane and the question was talking about the two that weren't butane.
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    (Original post by Splaffie)
    an isomer ALWAYS has the same molecular formula, they had the same mr but a different molecular formula, different molecules can have the same mr, for example c2h6 and h2c=o have the exact same mr but they are definitely not isomers
    Are you sure they had different molecular formulae? I counted the number of atoms of each element and got the same number for each
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    (Original post by neon_reaper)
    There were 3 molecules, 2 of them were isomers and the third was butane and the question was talking about the two that weren't butane.
    pretty sure it was all 3 since butane has the same mr as propan-1-ol
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    What did everyone get for the last multiple choice question?
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    (Original post by Splaffie)
    pretty sure it was all 3 since butane has the same mr as propan-1-ol
    Ahhhh no butane has no oxygen atoms so it is not an isomer
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    (Original post by marcobruni98)
    Ahhhh no butane has no oxygen atoms so it is not an isomer
    propanal and propanol are isomers, butane isnt, but they all had the same mr, the question was talking about why all 3 cant be determined by mass spectrometry and its because they all had the same mr
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    (Original post by Al_YG)
    What did everyone get for the last multiple choice question?
    C if it was the one about pressure and argon
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    (Original post by Splaffie)
    C if it was the one about pressure and argon
    Part C had the same increase in moles for Argon and had less of an increase in temperature? Do had a higher increase in temp for the same increase in moles (0.5)
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    (Original post by Al_YG)
    What did everyone get for the last multiple choice question?
    It was D. There was a relatively quick way to do it which was change PV = nRT into P=nT/V (R is a constant so you can ignore it). You could then sub in 1 for V because volume was a constant, then you could just keep changing the moles, temperature and volume as needed
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    D not Do apologies...
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    (Original post by Splaffie)
    pretty sure it was all 3 since butane has the same mr as propan-1-ol
    I'm pretty sure it was just the first two (what was it, propanal and prop-2-en-1-ol?) but I could be wrong, butane definitely wasn't an isomer though.
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    (Original post by neon_reaper)
    It was D. There was a relatively quick way to do it which was change PV = nRT into P=nT/V (R is a constant so you can ignore it). You could then sub in 1 for V because volume was a constant, then you could just keep changing the moles, temperature and volume as needed
    p is directionally proportional to both n and t, so multiply t by 1.5 and it came to 195 which was the highest value for all of them

    for d the temperature change was 280, but a decrease of 0.5 moles gave you a value of 140
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    (Original post by neon_reaper)
    I'm pretty sure it was just the first two (what was it, propanal and prop-2-en-1-ol?) but I could be wrong, butane definitely wasn't an isomer though.
    it was propanal prop-2-en-1-ol and butane
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    (Original post by neon_reaper)
    It was D. There was a relatively quick way to do it which was change PV = nRT into P=nT/V (R is a constant so you can ignore it). You could then sub in 1 for V because volume was a constant, then you could just keep changing the moles, temperature and volume as needed
    There was an even quicker way which was to see the huge increase in temp for D and compare it with B's answer for one mole...lol D was the answer therefore.. what about the second to last. Sorry for bragging but no-one has answered all 15 multiple choices (only the first 12).
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    (Original post by Splaffie)
    p is directionally proportional to both n and t, so multiply t by 1.5 and it came to 195 which was the highest value for all of them

    for d the temperature change was 280, but a decrease of 0.5 moles gave you a value of 140
    I am pretty sure that both C and D were increases in 0.5 moles?
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    (Original post by Splaffie)
    propanal and propanol are isomers, butane isnt, but they all had the same mr, the question was talking about why all 3 cant be determined by mass spectrometry and its because they all had the same mr
    Propanal and propanol are not isomers
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    (Original post by Al_YG)
    I am pretty sure that both C and D were increases in 0.5 moles?
    d was a decrease of 0.5 moles
 
 
 
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