Dehydration Flashcards
(17 cards)
What is the mobile phase in gas chromatography?
inert gas
What is the stationary phase in gas chromatography? (2)
- a thin film of highly polar polymer
- typically a liquid
What is the process of gas chromatography? (4)
1) the liquid sample is injected into the injector port, then vaporized
2) Gas flows through gas chromatography carrying along the vaporized samples
3) The detector detects compounds after they are eluted off
4) The recorder generates a gas chromatogram
Retention Time (tR)
the time taken for a particular compound to travel through the column to the detector
Is retention time an intrinsic property?
no
Why would components have longer retention times? (2)
- they are polar so they adsorb to the stationary phase
- they have a high boiling point, so they spend more time as a liquid
What is gas chromatography used for? (2)
- characterization
- analysis
IR Spectroscopy
the analysis of infrared light interacting with matter
What happens when a chemical sample is exposed to IR light? (3)
- absorb some frequencies
- transmit the rest of the frequencies
- reflect some of the IR light back to the source
IR Spectrum (2)
- a plot of transmitted/absorbed frequencies versus intensity of the transmission/absorption
- reported in wave numbers
What happens when covalent bonds are exposed to IR light?
they behave like springs so they vibrate
What frequency do C=C bonds vibrate at?
1,650 - 1,800 cm-1
What frequency do C=O bonds vibrate at?
1,650 - 1,800 cm-1
What frequency do -OH bond vibrate at?
3,200 - 3,400 cm-1
What frequency do sp3 C-H bonds vibrate?
2,850 - 2,975 cm-1
What frequency do sp2 bonds do C-H bonds vibrate?
3,020 - 3,100 cm-1
How can peaks be described? (4)
- strong
- medium
- weak
- broad
