Lab Exam 2- IR spectroscopy

where is the functional group region?

in the high energy region

where is the fingerprint region?

in the low energy region

what is IR spectroscopy primarily used for?

to detect functional groups present

IR absorptions arise due to

stretching and bending of covalent bonds in molecules

100% transmittance means that

all light is shone is transmitted, and none is absorbed

0% transmittance means that

none of the light shone is transmitted, all is absorbed

the fingerprint region is used for

structure elucidation by spectral comparison

wavenumber is proportional to

frequency

wavenumber is inversely proportional to

wavelength

increasing wavenumber corresponds with

increasing energy

wavenumber is measured in

cm-1

what range of wavenumber are single bonds found in?

400-1500

what range of wavenumber are double bonds found in?

1500-2000

what range of wavenumber are triple bonds found in?

2000-2500

bonds to hydrogen are found in what wavenumber range?

2500-4000

stronger bonds proportional to

higher frequencies

lighter atoms are proportional to

higher frequencies

anhydride IR peaks?

1820 and 1760 cm-1

what is the C=O IR range?

1690-1820

O-H stretching region

3300-3600 cm-1

alcohol when they are free, how does it affect the stretching?

sharp peaks, no H-bonding (3600 cm-1)

Alcohols and carboxylic acids stretching

broad peaks due to H-bonding (3300 cm-1)