4.2.4 - Analytical Techniques Flashcards
What happens when IR radiation is absorbed?
It is absorbed by the covalent bonds in the molecules, increasing their vibrational energy.
Why can we use IR spectrometry to find the functional group of a molecule?
Bonds between different atoms absorb different frequencies.
Describe the greenhouse effect.
Various gases in the atmosphere contain C=O, C-H or O-H bonds which are able to absorb IR and emit it in all directions.
What are the 3 main greenhouse gases?
Water vapour, carbon dioxide and methane.
What are the uses of IR spectroscopy?
Breathalysers and for monitoring concentrations of polluting gases in the atmosphere.
How is IR used in breathalysers?
The amount of ethanol vapour is found by measuring the intensity of the peak corresponding to the C-H bond in the IR spectrum.
What are the poisonous emissions produced by cars?
NO and CO
How do you find the RMM of a compound from a mass spectrometer?
The molecular peak, which is the highest value on the graph.
Why may there be something after the molecular peak?
Due to the presence of carbon isotope C-13.
What do the different lines on the mass spectrometer represent?
The molecular ion broken into smaller fragments.
