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A-level Chemistry > Mass Spectroscopy > Flashcards

Mass Spectroscopy Flashcards

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1
Q

What is mass Spectroscopy?

A

A method of identity unknown compounds

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2
Q

What is the main use of mass spectroscopy?

A

Identifying unknown compounds

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3
Q

What are some uses of mass spectroscopy?

A

~ identifying unknown compounds
~detecting banned substances such as steroids in athletes
~determining the abundance of an isotope of an atom

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4
Q

How many stages are there in mass spectrometry?

A

4

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5
Q

What happens during the ionisation stage of mass spectrometry?

A
  • A sample of an element is vaporised and injected into the mass spectrometer, where a high voltage is passed over the chamber.
  • High energy electrons are then fired at the element, resulting in the loss of an electron/s and a positive ion being formed.
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6
Q

What happens during the Acceleration stage of mass spectrometry?

A
  • ## Positively charged ions are accelerated towards a negatively charged detection plate.
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7
Q

What causes the defelction of ions in mass spectrometry?

A

The presence of a magnetic field

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8
Q

What happens during the Ion Drift stage of Mass Spectrometry?

A

-The ions are deflected by a magnetic field into a curved path.

  • The radius of the path is dependent on the charge and the mass of the ion.
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9
Q

What happens during the Detection Stage of Mass Spectrometry ?

A
  • A flow of charge is produced and the greater the size of the current produced, the greater the abundance of that particular ion.
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10
Q

What happens during the Analysis Stage of Mass Spectrometry?

A
  • A spectra is produced from the current values and the flight time and the spectra will display the relative abundance of each isotope displayed.
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11
Q

Can mass spectroscopy give us an idea of the different isotopes of an atom?

A

Yes

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12
Q

What is a molecular ion?

A

The positive ion formed in mass spectrometry when a molecule loses an electron

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13
Q

What is fragmentation?

A

The process in mass spectrometry that causes a positive ion to split into pieces, one of which is a positive fragment ion

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14
Q

Why do the isotopes of an elememt react in the same way?

A

Because they all have the same electronic configuration

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15
Q

What does the abundance tell us?

A

How common each isotope os

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16
Q

What does each positive ion gain from the detector?

A

Electrons e.g ions with a single positive charge will gain a single electron

17
Q

What is used to determine the abundance of each isotope?

A

The size of the current produced when each isotope hits the detector

18
Q

Will a more abundant isotope produce a lesser or greater current?

A

A greater current

19
Q

What is the interior of the mass spectrometer?

A

A vacuum to prevent the molecules from colliding with molecules in the air

20
Q

What does m/z represent?

A

Mass to charge ratio

21
Q

What are the 2 isotopes of chlorine?

A

Chlorine 37 and chlorine 35

22
Q

Why can mass spectrometry be carried out to a high level of precision?

A

Becasue the mass spectre can be detected to 5 decimal places

23
Q

What is it called when mass spectrometry is carried out to one decimal place?

A

The process is called low resolution mass spec

24
Q

After ionisation, what are we left with?

A

A molecule that has a positive charge and a radical

25
Q

Does mass spectra only produce peaks at the positive charges, not the radicals?

A

Yes, only at the positive charges

26
Q

Which part of the mass spectrometer separates ions of different masses?

A

The magnetic field

27
Q

What is an isotope?

A

An element with the same number of protons, but a different number of neutrons

28
Q

Id the ion detected by the mass spectrometer had lost 2 electrons instead of one, what would the size of the peak be like?

A

The size of the peak would be halved

29
Q

What causes a molecular ion peak to not be formed in the mass spectrum?

A

The molecular ion being unstabl e

30
Q

How does burning with a smoky flame affect the value of the experimentally determined enthalpy change of combustion?

A
  • As this is incomplete combustion, the value will be less exothermic than the data book value.

A-level Chemistry (19 decks)

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