Structure Determination + Chromatography

What is NMR spectroscopy?
Nuclear magnetic resonance spectroscopy. It is a technique that helps find the structures of molecules, including complex ones.
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how does NMR work?
a magnetic field is applied to a sample. This generates an energy change in the nuclei of atoms in the sample that can be detected. Electromagnetic energy is emitted and this can then be interpreted by a computer.
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What is the chemical shift?
The relation of frequencies between the resonating nucleus and that of TMS.
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What is chemical shift measure in? What is it measured in relation to? (molecule)
Parts par million (ppm), Tetramethylsilane
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what is chromatography?
a separation technique
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what is the definition of the mobile phase?
this is what carries the sample through the chromatography technique. The more soluble the sample the faster it moves. Normally the liquid
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what is the definition of the stationary phase
this will hold back the components that are attracted to it, the higher the affinity the sample has to the paper the slower it moves with the solvent.
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Advantages of thin layer chromatography: (4)
it runs faster - smaller amounts of mixtures can be separated - the spots usually spread out less - the plates are more robust than paper.
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how do you work out Rf value?
Rf = Distance travelled by the spot(measured from the middle)/Distance travelled
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Describe collum chromatography:
Uses a powder such as silica, aluminium oxide or a resin. The sample is added to the top of the column and the elements are separated as they travel down.
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Describe gas chromatography:
stationary phase is also a powder coated in oil. mobile phase is an unreactive gas such as nitrogen or helium. The different elements present have different retention times and are detected by the computer and makes a GC trace of RT times.
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GCMS
gas chromatograph mass spectrometer
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Other cards in this set

Card 2

Front

how does NMR work?

Back

a magnetic field is applied to a sample. This generates an energy change in the nuclei of atoms in the sample that can be detected. Electromagnetic energy is emitted and this can then be interpreted by a computer.

Card 3

Front

What is the chemical shift?

Back

Preview of the front of card 3

Card 4

Front

What is chemical shift measure in? What is it measured in relation to? (molecule)

Back

Preview of the front of card 4

Card 5

Front

what is chromatography?

Back

Preview of the front of card 5
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