iron has three main naturally occuring isotopes which can be investigated using a mass spectrometer. The first stage in the operation of the mass spectrometer is vaporization. The iron is then oxidized. Explain why the iron is oxidized.

Question

Explain why a very low pressure is maintained inside the mass spectrometer.

Answer 1

Stage 1 is Fe(s) + heat ==> Fe(g)
State 2 is Fe(g)==> Fe^3+(g) + 3e
and since the loss of electrons is the definition of oxidation, the Fe is oxidized. Note that the mass specrometer may or may not remove three electrons, you could make Fe^+ or Fe^++ or Fe^+++.

Why is the mass spectometer operated in a vacuum (at least as close to a vacuum as possible) because you don't want the Fe ions (Fe^+ or whatever ion it is) bouncing into air molecules on it's curved path from the ionization chamber to the readout device.