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2007-03-03 02:53:01 · 3 answers · asked by sci_hima 1 in Science & Mathematics Chemistry

3 answers

For the chemist, both are useful for spectroscopic determination of either concentrations of species or structure. Organic chemists use IR, as certain functional groups absorb infrared radiation at distinct wavelengths (or more commonly wavenumbers, the inverse of wavelength) which induces vibration in the molecule. UV light, and into the visible region, can be used to determine the concentration of species produced from reaction with various other reagents, or simply the species itself if it is known that UV light is absorbed by the molecule during excitation of electrons.

2007-03-03 03:00:07 · answer #1 · answered by TheOnlyBeldin 7 · 1 0

Both IR and UV are qualitative tests used in identifying organic compounds (and inorganc compounds, although I'm an organic chemist, so I'll focus on the organic chemistry part of it).

IR can show which functional groups (double bonds, triple bonds, esters, ketones, alcohols, etc.) are present in a molecule. There are libraries of IR spectra, which means in theory you can take an IR spectra of an unknown, and figure out what it is by matching it to its unique IR spectrum. On TV shows like CSI this always works. In an organic chemistry lab, almost nobody would rely on matching IR spectrum alone to determine the identity of a compound.

UV offers similar functional group determination, although it is not as good as IR. UV spectroscopy can also be a quantitative tool--i.e. you can determine how much of something is present--and is used rather broadly for this purpose. This is used to determine some ion concentrations, protein concentrations, or determine how well a biochemistry experiment is working.

2007-03-03 11:32:49 · answer #2 · answered by davisoldham 5 · 2 0

The uv is normally used for the substitution method in alkane.the uv tend to breakin the bond between the molecule that will replace with the hydrogen atom in alkane (carbon compound).

2007-03-03 11:56:10 · answer #3 · answered by amir s 1 · 0 0

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