4.2.4 analytical techniques Flashcards
1
Q
what is infrared spectroscopy and how is it used
A
- measures certain bonds in a molecule absorbing infrared radiation at characteristic frequencies that cause covalent bonds to vibrate
- a computer then compares IR spectra to a database to identify the compound
2
Q
what is the greenhouse effect
A
- CO2, methane and water vapour are greenhouse gases and they trap the Earth’s radiated IR energy in the atmosphere
- the IR radiation is absorbed by C=O, O-H and C-H bonds which then contribute to global warming
3
Q
what contribution does CO2 have to global warming
A
- concentrations of CO2 in the atmosphere have risen significantly due to increased burning of fossil fuels
- the greenhouse effect id dependent on the amount of CO2 in the atmosphere, its ability to absorb IR and how long it stays in the atmosphere
4
Q
how can infrared spectroscopy be used practically
A
- to monitor gases causing air pollution
- modern breathalysers to measure levels of ethanol in the breath
5
Q
what is the process of mass spectrometry
A
- when a molecule is put through a mass spectrometer it will break up to give a series of peaks caused by fragments
- the peak with the largest m/z is equal to the Mr and is called the molecular ion peak
6
Q
what is fragmentation
A
- the molecular ion fragments due to covalent bonds breaking
- more stables ions like carbocations will cause a greater peak intensity