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    (Original post by Mina_)
    Thanks!
    The link tells you why they have the spectra that they do!

    Read what it says about bromine and apply it to the chlorine MS
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    (Original post by charco)
    The link tells you why they have the spectra that they do!

    Read what it says about bromine and apply it to the chlorine MS
    I understand it for Br2 as the relative abundance for both isotopes is approx. 50% but I dont really understand why the Cl2 isotope relative abundance height is in a 9:6:1 ratio
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    (Original post by Mina_)
    I understand it for Br2 as the relative abundance for both isotopes is approx. 50% but I dont really understand why the Cl2 isotope relative abundance height is in a 9:6:1 ratio
    It's the statistical probability of each possible molecule occuring.

    If you choose two chlorine atoms at random there is a 3/4 probability of it being a 35Cl atom and a 1/4 probability of it being a 37Cl atom

    So if you consider the four possible combinations:

    35Cl35Cl probability 3/4 x 3/4 = 9/16
    35Cl37Cl probability 3/4 x 1/4 = 3/16
    37Cl35Cl probability 1/4 x 3/4 = 3/16
    37Cl37Cl probability 1/4 x 1/4 = 1/16

    The middle two molecules are the same mass hence there is a 6/16 probability of mass 72

    All of the probabilities add up to 1 (as they should) so you hae a ratio:

    mass 70 = 9
    mass 72 = 6
    mass 74 = 1

    And this is the intensity of the signals observed
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    (Original post by charco)
    It's the statistical probability of each possible molecule occuring.

    If you choose two chlorine atoms at random there is a 3/4 probability of it being a 35Cl atom and a 1/4 probability of it being a 37Cl atom

    So if you consider the four possible combinations:

    35Cl35Cl probability 3/4 x 3/4 = 9/16
    35Cl37Cl probability 3/4 x 1/4 = 3/16
    37Cl35Cl probability 1/4 x 3/4 = 3/16
    37Cl37Cl probability 1/4 x 1/4 = 1/16

    The middle two molecules are the same mass hence there is a 6/16 probability of mass 72

    All of the probabilities add up to 1 (as they should) so you hae a ratio:

    mass 70 = 9
    mass 72 = 6
    mass 74 = 1

    And this is the intensity of the signals observed
    This was extremely helpful! Thank you
 
 
 
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