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    Can someone help me with this question!

    A mass spectrum of a sample of antimony showed two peaks at m/z= 120 and m/z= 122. The relative atomic mass of this sample of antimony is 121.3. Use these data to calculate the ratio of the relative abundances of the two isotopes.
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    Just did it- pic will follow
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    (Original post by ohmickeyursofine)
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    Your answer is wrong. 122 must be more abundant than 120 as the relative atomic mass is 121.3
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    (Original post by Naya104)
    Can someone help me with this question!

    A mass spectrum of a sample of antimony showed two peaks at m/z= 120 and m/z= 122. The relative atomic mass of this sample of antimony is 121.3. Use these data to calculate the ratio of the relative abundances of the two isotopes.
    121 = 50:50 abundance

    Therefore, each 0.5 is worth 25% abundance
    Therefore, each 0.05 is worth 2.5% abundance

    121 + 0.05 x 6 = 121.3

    6 0.05s therefore 2.5 x 6 = 15%

    50 + 15 = 65

    Ratio is 35:65
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    Oh sorry woops it's been a long day- did it the wrong way round, it would be 120x and 122(100-x)
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    The other method works just as good- at least someone noticed the mistake!
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    Thank you
 
 
 
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