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Halogenoalkanes, Alcohols and Organic Analysis

Mass Spectrometry and Molecular Formula

  • 3 things to know
  • Papers 2 and 3

Overview

Time of flight mass spectrometry, relative atomic mass from isotopic abundances, the molecular ion peak, and using precise masses to find a molecular formula.

What you need to know

Answer each one before you reveal it.

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Key term

What information does mass spectrometry provide about isotopes?

Key term

What two quantities relating to isotopes can be determined from a mass spectrum?

Key term

What molecular property can mass spectrometry be used to determine?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What information does mass spectrometry provide about isotopes?

    Model answer

    Mass spectrometry provides accurate information about relative isotopic mass and the relative abundance of isotopes.

  2. 2

    What two quantities relating to isotopes can be determined from a mass spectrum?

    Model answer

    Relative isotopic mass and relative abundance of isotopes.

  3. 3

    What can mass spectrometry be used to identify?

    Model answer

    Elements.

  4. 4

    What molecular property can mass spectrometry be used to determine?

    Model answer

    Relative molecular mass.

  5. 5

    In a time of flight mass spectrometer, what is the first stage that occurs to the sample?

    Model answer

    Ionisation of the sample to form positive ions.

  6. 6

    After ionisation in a TOF mass spectrometer, what happens to the ions in the acceleration stage?

    Model answer

    The ions are accelerated to give all ions constant kinetic energy.

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Atomic Structure
Amount of Substance
Bonding
Energetics and Thermodynamics

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A atom.
nitrogencarbonsulfur

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AOxidation is the loss of electrons.
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The sum of all mole fractions equals 1.
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