Final answer:
Infrared spectroscopy is a technique used to identify functional groups in molecules by measuring absorption frequencies. It helps determine the presence or absence of specific groups in a molecule.
Step-by-step explanation:
Infrared spectroscopy is a technique used to identify different functional groups in molecules based on their characteristic absorption frequencies. It involves passing infrared light through a sample and measuring the frequencies that are absorbed. Different functional groups have different absorption frequencies, allowing scientists to determine the presence or absence of specific groups in a molecule. For example, if a sample absorbs in the carbonyl frequency range but not in the alkyne range, it can be inferred that the molecule contains a carbonyl group but not an alkyne.