Chemistry A-level question...

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    State how krypton is ionised in the mass spectrometer.
    Write an equation, including state symbols, to show the reaction that occurs when the first ionisation energy of Kr is measured.
    Sometimes the mass spectrum of Kr has a very small peak with an m/z value of 42. Explain the occurrence of the peak.
    (5 marks)

    Can someone please help me answer this and show me how they did it please .
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    What do you think is the answer?
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    I've only started Chemistry a level so i doubt i'll be of any help but we have done this so here goes nothing: (I can only help with the first part)

    Krypton is placed in to the ionisation chamber which produces positive ions. The positive ion now passes into a magnetic field where it is deflected. The deflection is dependent on the atomic mass and charge. Next, the ion is now detected. The detector shows the relative mass, charge on ion and percentage abundance.

    Once again, i had a shot at it. It's probably something completely different. Sorry! :s
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    I think this is the equation for ionisation of Kr:
    Kr(g) ---> Kr+(g) + e-
    Explain the occurrence of the 42 peak.
    I believe it's simply a different isotope of Kr.
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    (Original post by Becca_390)
    I think this is the equation for ionisation of Kr:
    Kr(g) ---> Kr+(g) + e-
    Explain the occurrence of the 42 peak.
    I believe it's simply a different isotope of Kr.
    Agreed.


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    (Original post by Becca_390)
    I think this is the equation for ionisation of Kr:
    Kr(g) ---> Kr+(g) + e-
    Explain the occurrence of the 42 peak.
    I believe it's simply a different isotope of Kr.
    Kryton has a mass ~84
    Certainly no isotopes anywhere close to 42
    Mass spectrometer measures m/z (ie mass over charge)
    The peak at 42 is therefore much more likely to be the result of a small amount of Kr2+
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    (Original post by MexicanKeith)
    Kryton has a mass ~84
    Certainly no isotopes anywhere close to 42
    Mass spectrometer measures m/z (ie mass over charge)
    The peak at 42 is therefore much more likely to be the result of a small amount of Kr2+
    Yep I think I made a mistake there, MexicanKeith is right. It's due to the small amount of Kr2+ ions. Sorry about that!!
 
 
 
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