UV-Vis and Mass Spectrometry

Question 1

UV/Vis Spectrophotometry

Answer 1

• Irradiating a sample with photons of UV or vis light of particular wavelength
• Liquid sample dispensed into a cuvette
• Must be run against a sample blank
• Light doesn’t pass through the sample
• Transmission light passes through the sample

Question 2

Molecular Orbital

Answer 2

The region in which there is
the highest probability of finding an electron of a
molecule

Question 3

Highest Occupied Molecular Orbital

Answer 3

• Highest energy MO with any electrons in it

Question 4

Lowest Unoccupied Molecular Orbital

Answer 4

The next highest energy orbital. It will be empty and so is the lowest energy orbital in which to place an electron or excite one into

Question 5

Beer’s Law

Answer 5

• Absorbance is what we measure
  and has arbitrary units
• The molar absorption coefficient
  is a standardThe concentration is in moldm-3
• The path length is the width of the
  cuvette