Spectroscopy Flashcards
What happens to an organic compound in a mass spectrometer?
it loses an electron and forms a positive ion - the molecular ion
What does a mass spectrometer detect?
the mass-to-charge ratio (m/z) of the molecular ion which gives the molecular mass
What is the molecular ion?
the positive ion formed when a molecule loses an electron
How do you determine the molecular mass from a mass spectrum?
the molecular ion peak is the largest no. peak
What is the symbol for the molecular ion peak?
M+
What is the M+1 peak?
a very small peak after M+ peak due to Carbon 13 or other isotopes
What is fragmentation?
in the mass spectrometer, some molecular ions break down into smaller pieces called fragments
What does fragmentation break a molecular ion up into?
a fragment ion and a radical
What is the m/z value of CH2OH+ fragment ion?
31
What is the m/z value for CH3+?
15
What is the m/z value for C2H5+ fragment ion?
29
What is the m/z value for C3H7+ fragment ion?
43
What is the m/z value for C4H9+ fragment ion?
57
What is the m/z value for CH3CH2O+ fragment ion?
45
How does infrared spectroscopy work?
molecules can absorb infra-red radiation
the energy that is absorbed causes the covalent bonds in the molecule to vibrate
What does the amount a bond streches or bends depend on?
the mass of the atoms in the bond = heavier—> slower vibration
the strength of the bond = stronger —-> faster vibration
How does global warmbing occur due to IR radiation?
greenhouse gases absorb IR radiation because it has the same natural frequency of their bonds
the vibrating bonds re-emit this energy as radiation
resulting in increasing the temp of the earth
What is infrared spectroscopy used for?
identifying the functional groups present in organic molecules
What does an infrared spectrum show?
the frequencies that have been absorbed by the bonds
What is the fingerprint region?
peaks below 1500 wavenumber - (dont need to indentify these peeks)
What does an OH alchohol bond peak on infrared spectrum look like?
tall and broad, no spiking
What does a C-H bond look like on an infrared spectrum?
small spikes
What does a caroxyl OH infrared peak look like?
broad but has C-H spikes on the right side
What is the application of infrared spectroscopy?
used to identify pollutants - CO, CO2 and hydrocarbons
breathalysers for the presence of ethanol
traces of drugs
water and air quality monitoring - environmental pollutants