Spectroscopy and Chromatography Flashcards
What does n refer to in the n + 1 rule?
the number of H’s attached to the ADJACENT C atom.
Describe how IR spectroscopy works.
Molecules absorb IR by vibrating with increased K.E., different bonds have different specific VIBRATIONAL F dependent on bond strength –> absorb radiation at specific frequencies, wavelengths in IR region of spectrum.
How do microwaves heat a substance?
polar molecules rotate with magnetic field + collide.
What is beneficial about microwaves?
higher reaction temps –> increased reaction rates, product yield + less energy required.
What in the body reacts with what sort of radiation in MRI scanners?
H1 nuclei in water - radio waves.
What effect does H bonding have on the peak due to an -OH group?
broadens peak as as changes -OH bond length –> all vibrate at slightly different fs.
When is gas chromatography often used?
in industry to monitor the presence or absence of materials at different stages of a process.
What is the advantage of HPLC?
can be carried out at RT so bio and organic molecules can be separated as well as studying events when drugs are metabolised.
what is the retention time of a compound dependent on?
Solubility in the mobile phase and adsorption to the stationary phase.
what is gas chromatography often combined with and why?
MS - similar compounds have similar retention times.
