📝 Infrared spectroscopy

Task

🎧️ Listen to the recording and mind pronunciation of words.

Infrared spectroscopy is an analytical technique that provides information about the functional groups present in a compound. Certain groups of atoms absorb characteristic frequencies of infrared radiation as the bonds between them undergo transitions between different vibrational energy levels. The particular wavelengths absorbed are specific to that particular configuration of bonds and atoms (functional group). Any wavelength that is absorbed by the sample will transmit less than the others, forming a dip in the graph. The pattern in the fingerprint region (1500-400 cm^-1) is unique to each molecule and so can be used for identification purposes. Some uses of infrared spectroscopy include:

• Following the progress of a reaction involving a change of functional groups (e.g. in the chemical industry to determine the extent of the reaction).
• To assess the purity of a compound.
• Modern breathalyzers calculate the percentage of ethanol in the breath by looking at the size of the absorption caused by the C–H bond stretch in the alcohol.

Practice Exercises