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Chromatography

Phase: a physically distinctive form of a substance

Chromatography is an analytical technique that separates components in a mixture between a mobile
phase and a stationary phase.

The stationary phase interacts with the components in the mixture, slowing them down.

This allows different compounds to flow over the stationary…

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Limitations:

Sample may have chemicals with the same retention time and peak shape
Substance may hide behind another
Unknown compounds have no retention times to compare to

Uses of GC-MS

Forensics
Space Probes
Airport security
Environmental analysis

NMR

NMR involves interaction of materials with low energy radio waves.

Chemical shift:…

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Spin-spin coupling gives info about adjacent protons

-OH and NH protons are difficult to identify:

Peaks have a wide range of shift values
Signals are broad
No splitting

D2O or CDCl3 is used as it does not produce a signal. The D swaps with the H in NH and OH…

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Benzene

Kekule said that Benzene had alternating double bonds. This cannot be true, however, because:

If C=C bonds were present then benzene would react like alkenes.
Each C=C bond would react with bromine water.

To fix this Kekule said that two forms of benzene existed, both with alternating C=C bonds.…

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Phenols

Phenol is benzene with an OH group attached.

When dissolved in water, phenol forms a weak acidic solution by losing H+ from the ­OH group:

C6H6 + aq C6H5O- + H+

When a metal reacts with phenol, hydrogen gas and a salt is produced.

Phenols are used as antiseptic…

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