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    I'd like some help with this question:

    "The element bromine has two isotopes, Bromine-79 and Bromine-81. How many peaks corresponding to Br2 + ions would be seen in the mass spectrum of bromine? Justify your answer. (2)"

    I have found the answer, but I just don't understand it:
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    (Original post by arniebob)
    I'd like some help with this question:

    "The element bromine has two isotopes, Bromine-79 and Bromine-81. How many peaks corresponding to Br2 + ions would be seen in the mass spectrum of bromine? Justify your answer. (2)"

    I have found the answer, but I just don't understand it:
    Spoiler:
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    I think it's something to do with probability
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    becasue Bromine is a group 7 halogen, it's found as Br2, similar to chlorine Cl2, and Iodine, I2.

    Hence, in the mass spectrometer because either atom could be either isotope, for Br2 there are 3 combinations of atoms, 79-79, 79-81, or 81-81.

    Furthermore, the + is because the molecule is ionised in the mass spectrometer.

    It doesn't matter about 79-81 vs 81-79 because it's the same molecule but flipped.

    Hope this helps, feel free to ask for more explanation if required
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    (Original post by RThornton)
    becasue Bromine is a group 7 halogen, it's found as Br2, similar to chlorine Cl2, and Iodine, I2.

    Hence, in the mass spectrometer because either atom could be either isotope, for Br2 there are 3 combinations of atoms, 79-79, 79-81, or 81-81.

    Furthermore, the + is because the molecule is ionised in the mass spectrometer.

    It doesn't matter about 79-81 vs 81-79 because it's the same molecule but flipped.

    Hope this helps, feel free to ask for more explanation if required
    Ah I see now, thanks for the help
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    (Original post by arniebob)
    I'd like some help with this question:

    "The element bromine has two isotopes, Bromine-79 and Bromine-81. How many peaks corresponding to Br2 + ions would be seen in the mass spectrum of bromine? Justify your answer. (2)"

    I have found the answer, but I just don't understand it:
    Spoiler:
    Show
    Because isotopes are chemically identical, all isotopes (well not strictly but for this example) of an element can bond as any isotope of that element would.

    Therefore you can get Br2 made up of just Br-81 isotopes, just Br-79 isotopes or one of each isotope. Therefore 3 peaks.
 
 
 
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