UV-Vis spectroscopy is a technique that measures the absorption of ultraviolet UV and visible light by a compound. The absorption of light occurs when the energy of the photons matches the energy difference between the ground state and an excited state of the molecule. This energy difference is related to the electronic structure of the molecule, which in turn is influenced by the presence of specific functional groups.To differentiate between compounds containing a phenyl and an ethyl group using their UV-Vis spectra, you would need to analyze the differences in their absorption patterns. Here's how you can do that:1. Obtain the UV-Vis spectra of the compounds: First, you need to obtain the UV-Vis spectra of the compounds containing the phenyl and ethyl groups. This can be done by dissolving the compounds in a suitable solvent and measuring their absorbance at different wavelengths using a UV-Vis spectrophotometer.2. Identify the characteristic absorption bands: Each functional group has a characteristic absorption band in the UV-Vis region. For phenyl groups, the characteristic absorption bands are due to -* transitions and are typically found in the range of 200-300 nm. Ethyl groups, on the other hand, do not have strong absorption bands in the UV-Vis region due to the lack of electrons. However, they may show weak absorption bands in the range of 175-200 nm due to -* transitions.3. Compare the spectra: By comparing the UV-Vis spectra of the compounds, you can identify the presence of a phenyl or an ethyl group based on the characteristic absorption bands. If the compound shows a strong absorption band in the range of 200-300 nm, it is likely to contain a phenyl group. If there is no strong absorption in this range, but a weak absorption band is observed in the range of 175-200 nm, it may indicate the presence of an ethyl group.4. Confirm the presence of the functional groups: To further confirm the presence of the phenyl or ethyl group, you can use other analytical techniques such as infrared IR spectroscopy, nuclear magnetic resonance NMR spectroscopy, or mass spectrometry MS . These techniques provide complementary information about the molecular structure and can help you confirm the presence of specific functional groups in the compound.In summary, UV-Vis spectroscopy can be used to differentiate between compounds containing phenyl and ethyl groups by analyzing their characteristic absorption bands. However, it is essential to use additional analytical techniques to confirm the presence of these functional groups.